ANSYS Fluent - CFD Final year thesis

Computational aerodynamic analysis of a

rear spoiler on a car in two dimensions

By

Dibyajyoti Laha

(Student No: 1227201)

Supervisor

Dr. Ahad Ramezanpour

A dissertation submitted in partial fulfilment for the degree

Of

Bachelor of Engineering Honours (Engineering: Mechanical)

In

Mechanical Engineering

Faculty of Science & Technology

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ACKNOWLEDGMENT

This research paper is a report of “Aerodynamics of a rear spoiler on a car in 2D using CFD

software to analyse the results”. It was only possible through the help of the course moderators including:

Lecturers, industrial CFD consultants, and in essence, all sentient beings. On the same occasion, please allow

me to dedicate my acknowledgment of gratitude towards the following significant lectures and contributors

for the research project.

First and foremost, I would like to show my gratitude and thanks to Dr. Ahad Ramezanpour for his

dedication to teach the every bits and parts of the thermodynamics and ANSYS Fluent which have been a

major use in the research project and devoting his invaluable time along with advice to hold a grip on the

report writing. He spent his class lectures to find the best possible solutions to the problems generated while

studying and helping to improve the standard of the brainstorming the solutions for the report. Not only being

a professor, he has been a great mentor & supervisor for the project with priceless feedback.

Secondly I would like to thank Dr. Habtom Mebrahtu in advising to write a research report referring IET

publications as my personal tutor at Anglia Ruskin University, Anglia Ruskin University for providing the

infrastructure and the ANSYS Laboratory for conducting the research. I would also like to extend my

gratitude to my colleague Miss Ambika Samanta for assisting and explaining the research survey, software

at times when needed.

Alongside my parents, my father Mr. Dilip Kumar Laha, Deputy Site Manager, Jacobs Engineering India

Pvt. Ltd, a Jacobs Engineering for briefing me and making me understand the investment of potential in the

world of designing and Finite Element Analysis in industrial background and my mother Mrs. Chaitali Laha

for boosting my enthusiasm while studying abroad while also funding me financially for the project.

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DECLARATION BY THE AUTHOR

I hereby declare that the work in this report is my own except for quotations and summaries which have been

duly acknowledged by in citation references. I have clearly stated the contribution of others to the production

of this work as a whole. I have read, understood and complied with the Anglia Ruskin University academic

regulations regarding the assessment offences, including but not limited to plagiarism.

I have not used material contained in this work in any other submission for an academic award or part thereof.

I acknowledge and agree that this work may be retained by Anglia Ruskin Ruskin University and made

available to others for research and study in either an electronic format or paper format or both of these and

also may be available for library or inter-library loan. This is on the understanding that no quotation from this

work may be made without proper acknowledgment.

Candidate Signature: ……………………………………………………..

Candidate Student Number: ……………………………………………….

Date: ………………………………………………………………………..

3

Table of Contents

Table of Figures ................................................................................................................................................... 8

List of Tables: ................................................................................................................................................ 11

ABSTRACT ..................................................................................................................................................... 12

NOMENCLATURE: ............................................................................................................................... 13

Terms used: ....................................................................................................................................... 13

Variables relating to CFD results: ..................................................................................................... 13

CHAPTER - 1 ................................................................................................................................................... 14

INTRODUCTION ......................................................................................................................................... 14

1.1 PROJECT INTRODUCTION .................................................................................................... 15

1.2 PROBLEM BACKGROUND ..................................................................................................... 16

1.3 PROJECT AIM & OBJECTIVE ............................................................................................... 17

1.4 DISSERTATION DESCRIPTION ............................................................................................ 17

1.5 PROJECT SURVEY & OBSERVATION ................................................................................ 18

1.6 PROJECT LIMITATION .......................................................................................................... 19

CHAPTER 2 ...................................................................................................................................................... 20

LITERATURE REVIEW & THEORITICAL BACKGROUND ................................................................ 20

2.1 LITERATURE REVIEW ........................................................................................................... 21

2.2 GENERAL CONCEPTS ............................................................................................................. 24

2.2.1 LIFT CONCEPT ................................................................................................................... 24

2.2.2 DRAG CONCEPT ................................................................................................................. 25

2.2.3 BERNOULLI’S EQUATION ............................................................................................... 26

Application in the research model: .................................................................................................. 27

2.3 AERODYNAMIC FORCES ....................................................................................................... 28

2.3.1 DRAG FORCE ...................................................................................................................... 28

2.2.2 LIFT FORCE ......................................................................................................................... 28

2.3.3 DOWNFORCE ...................................................................................................................... 29

2.4 AERODYNAMIC PRESSURE DISTRIBUTION .................................................................... 30

Application in the research work: ...................................................................................................... 34

2.5 RELATION BETWEEN COFFICIENTS OF DRAG & LIFT ............................................... 34

2.6 AERODYNAMIC PRODUCT - REAR SPOILERS ................................................................ 34

2.6.1 HEIGHT OF REAR SPOLIERS ........................................................................................... 35

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2.7 CONTINUTY EQUATION ........................................................................................................ 37

Application in the research: ............................................................................................................... 38

2.8 NAVIER STOKES EQUATION ................................................................................................ 38


2.9 DIMENSIONAL ANALYSIS & SIMILITUDE ....................................................................... 40


CHAPTER 3 ...................................................................................................................................................... 41

METHODOLOGY ........................................................................................................................................ 41

3.1 INTRODUCTION ...................................................................................................................... 42

3.1.1 QUALITATIVE VS. QUANTITATIVE: QUESTIONS & APPROACH ............................ 42

Qualitative Methods: ..................................................................................................................... 42

Coherence of qualitative method in the research work: .................................................................... 42

Quantitative Methods: ................................................................................................................... 43

Coherence of qualitative method in the research work: .................................................................... 43

3.2 ENGINEERING DETERMINING METHODS ..................................................................... 44

3.2.1 EXPERIMENTAL METHOD: ............................................................................................. 44

3.2.2 ANALYTICAL METHOD: .................................................................................................. 45

3.2.3 NUMERICAL METHOD: .................................................................................................... 45

1. Finite Difference Method: ......................................................................................................... 45

2. Finite Element Method: ............................................................................................................. 46

3. Finite Volume Method: ............................................................................................................. 46

3.3 COMPUTATIONAL FLUID DYNAMICS ............................................................................. 47

3.3.1 INTRODUCTION TO CFD .................................................................................................. 47

3.3.2 HOW DOES CFD MAKE PREDICTIONS? ........................................................................ 47

3.3.3 CFD ANALYSIS PROCESS ................................................................................................ 48

3.3.4 MESHING ............................................................................................................................. 49

1. Structured mesh generation: .............................................................................................................. 49

a. Algebraic grid generation: ............................................................................................................. 50

b. PDE Mesh generation: ................................................................................................................... 50

2. Unstructured mesh generation: ...................................................................................................... 51

3.3.5 MESH QUALITY ................................................................................................................. 53

1. Mesh Element Distribution:.......................................................................................................... 53

2. Cell Quality: ................................................................................................................................. 54

3.3.6 BOUNDARY CONDITIONS ............................................................................................... 54

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Inlet & Outlet Boundary: ................................................................................................................... 54

3.3.7 COMPUTING SETUP .......................................................................................................... 55

3.3.8 CONVERGENCE ................................................................................................................. 56

3.3.9 ERRORS................................................................................................................................ 56

Physical Errors: ................................................................................................................................. 56

Discretization Error: .......................................................................................................................... 57

Programming Errors: ......................................................................................................................... 57

Computer-round off Errors: ............................................................................................................... 57

Iterative Convergence Error: ............................................................................................................. 57

CHAPTER 4 ...................................................................................................................................................... 58

NUMERICAL SETUP .................................................................................................................................. 58

4.1 INTRODUCTION ....................................................................................................................... 59

4.2 DEVELOPING THE DIGITAL BASE LINE MODEL .......................................................... 60

4.2.1 GEOMETRY ......................................................................................................................... 60

4.3 MODELING IN THE INVENTOR 2014...................................................................................... 61

4.4 DESIGNING THE BLM ............................................................................................................... 61

Original Specifications: ......................................................................................................................... 61

Inventor Steps: ....................................................................................................................................... 62

Step 1: Initial Setup ........................................................................................................................... 62

Step 2: Selecting the design sketch .................................................................................................... 62

Step 3: Selecting the work plane ....................................................................................................... 63

Step 4: Importing Image based design .............................................................................................. 63

Step 5: Designing using points .......................................................................................................... 64

Step 6: Finalising the sketch and dimensioning ................................................................................ 64

Step 7: Creating the boundary walls .................................................................................................. 65

Step 8: Generating the Boundary surface .......................................................................................... 65

4.4.1. BLM PRESENTATION ........................................................................................................ 67

4.5 MODEL WITH BUILT-IN SPOILER BY MANUFACTURER ............................................ 68

4.6 MODEL WITH DECKLID SPOILER ...................................................................................... 69

4.7 MODEL WITH OPEN TYPE SPOILER ................................................................................. 71

4.8 ANSYS WORKBENCH SETUP ................................................................................................ 72

Step 1: Extracting the CAD file ......................................................................................................... 72

Step 2: Updating the boundary condition for the FLUENT .............................................................. 73

Step 3: Setting the Meshing ........................................................................................................... 76

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Step 4: FLUENT Setup................................................................................................................. 79

4.9 POST PROCESSING SET UP ................................................................................................... 80

4.10 RESIDUALS & ERRORS ......................................................................................................... 86

CHAPTER 5 ...................................................................................................................................................... 87

ANSYS FLUENT RESULTS & ANALYSIS ............................................................................................... 87

5.1 INTRODUCTION ....................................................................................................................... 88

5.2 ANALYSIS FOR BLM ............................................................................................................... 88

Velocity Contours: ............................................................................................................................. 88

Pressure Contours: ............................................................................................................................. 89

Static pressure .................................................................................................................................... 90

Turbulence Contours: ........................................................................................................................ 90

5.3 ANALYSIS FOR MANUFACTURER MODEL ...................................................................... 91




5.4 ANALYSIS FOR DECK LID SPOILER .................................................................................. 96




5.5 ANALYSIS FOR OPEN STYLE SPOILER ............................................................................. 99


Pressure Contours: ........................................................................................................................... 100

Turbulence Contours: ...................................................................................................................... 101

5.6 VELOCITY MAGNITUDE COMPARISION TABLE: ....................................................... 102

5.7 PRESSURE COMPARISION: ................................................................................................. 104

5.8 TURBULENCE COMPARISION ........................................................................................... 107

5.9 RESULTANT FORCES............................................................................................................ 109

CHAPTER 6 .................................................................................................................................................... 111

CONCLUSION & FUTURE SCOPE ......................................................................................................... 111

Conclusions ............................................................................................................................................ 112

Future Scope .......................................................................................................................................... 113

REFERENCES ................................................................................................................................................ 114

APPENDICES ................................................................................................................................................. 118

APPENDIX 1 ......................................................................................................................................... 118

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What Are the Navier-Stokes Equations? ............................................................................................. 118

How Do They Apply to Simulation and Modeling? ................................................................................ 118

Example: Laminar Flow Past a Backstep ................................................................................................ 118

Different Flavours of the Navier-Stokes Equations................................................................................. 120

About the Reynolds and Mach Numbers ............................................................................................. 120

Low Reynolds Number/Creeping Flow ............................................................................................... 120

About the Experiment ...................................................................................................................... 121

Modeling the Experiment ................................................................................................................ 121

Flow Compressibility .......................................................................................................................... 123

Incompressible Flow ....................................................................................................................... 123

Compressible Flow .......................................................................................................................... 123

What Flow Regimes Cannot Be Solved by the Navier-Stokes Equations? ............................................. 125

APPENDIX 2 ......................................................................................................................................... 127

RESEARCH PROPOSAL .................................................................................................................... 127

1. RESEARCH INTRODUCTION ................................................................................................. 127

2. RESEARCH AIM ................................................................................................................... 128

3. RESEARCH OBJECTIVE ...................................................................................................... 128

4. RESEARCH LITERATURE REVIEW .................................................................................. 129

5. RESEARCH METHODOLOGY ............................................................................................ 130

PROJECT LIMITATIONS.......................................................................................................... 130

6. OBSERVATIONS & CALCULATIONS ............................................................................... 131

7. RESEARCH CONCLUSION .................................................................................................. 131

RESEARCH ETHICS APPLICATION FORM ................................................................................. 132

CV, Cover Letter and Exit Plan ........................................................................................................... 138

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Table of Figures

Figure 1 Showing spoiler at the back of a sedan car ......................................................................................... 15

Figure 2 Front Spoiler on Maserati ................................................................................................................... 15

Figure 3 Open type rear spoiler ......................................................................................................................... 15

Figure 4 Flow of air around a car generating pressure areas & lift directions .................................................. 16

Figure 5 Built-in spoiler .................................................................................................................................... 18

Figure 6 Aftermarket deck lid spoiler................................................................................................................ 18

Figure 7 Different types of spoilers available in market. .................................................................................. 18

Figure 8 Wind tunnel test .................................................................................................................................. 20

Figure 9 Failed La Bomba car. .......................................................................................................................... 21

Figure 10 Dimitris first aerodynamic car design ............................................................................................... 21

Figure 11 Water drop shape .............................................................................................................................. 21

Figure 12 Water drop shaped car Persu ............................................................................................................. 21

Figure 13 Porsche 911 streamline car................................................................................................................ 22

Figure 14 Volkswagen Beetle ........................................................................................................................... 22

Figure 15 Coefficient of drag value of cars changing over decade ................................................................... 22

Figure 16 Opel's GT a failure model with spoiler ............................................................................................. 23

Figure 17 shows the direction of flow, Lift and drag ........................................................................................ 25

Figure 18 Flow of air/ fluid around a spherical body to demonstrate low and high pressure regions ............... 26

Figure 19 a.) Left shows the low pressure. b) Values of coefficient of pressure around the geometry .......... 27

Figure 20 shows downforce generated due to spoiler. ...................................................................................... 29

Figure 21 shows airflow in profile for the Nissan R35 GTR ............................................................................ 30

Figure 22 shows region of high (blue) & low (yellow) pressure of a corvette Stingray ................................... 31

Figure 23 Pressure Coefficients Plotted Normal to surface............................................................................... 32

Figure 24 Region of high & low pressure around a car ..................................................................................... 32

Figure 25 Variation of Cp along with the geometry .......................................................................................... 33

Figure 26 shows the region of high & low pressure along with the car geometry. ........................................... 33

Figure 27 Gillespie experiment of how height of spoiler affects the pressure. ................................................. 35

Figure 28 Variance of pressure coefficient along .............................................................................................. 35

Figure 29 Pressure coefficient along the front end and rear end with & without spoiler .................................. 36

Figure 30 shows values change when spoiler retracts and in action ................................................................. 36

Figure 31 shows different mounting of the rear spoilers affect the Lift and the Drag coffieicient value .......... 36

Figure 32 Body used to show equation of continuity ........................................................................................ 37

Figure 33 showing the use of continuity in ANSYS Fluent .............................................................................. 38

Figure 34 Wind Tunnel test of spoiler on Porsche 911 Carrera ........................................................................ 41

Figure 35 Pie chart showing the three different methods of prediction ............................................................ 44

Figure 36 shows a fine structured mesh on a model .......................................................................................... 50

Figure 37 mapping of the physical coordinates on the x, y coordinates. ........................................................... 50

Figure 38 Generation of unstructured mesh of BMW 3 series model. .............................................................. 51

Figure 40 adjusting the element sizes and finding the number of elements ...................................................... 52

Figure 39 Meshing of the model with minimum 2 & maximum 4 mm element size ........................................ 52

Figure 41 meshing with default configurations ................................................................................................. 53

Figure 42 meshing obtained adjusting sizing .................................................................................................... 53

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Figure 43 defining the boundary conditions on geometry in ANSYS ............................................................... 55

Figure 44 obtaining convergence of the operating equations in ANSYS Fluent before post processing .......... 56

Figure 45 Top and bottom shows analysis of the models in the ANSYS .......................................................... 58

Figure 46 BMW 3 series dimensions ................................................................................................................ 61

Figure 47 Initial steps using inventor ................................................................................................................ 62

Figure 48 generating a 2D sketch on inventor ................................................................................................... 62

Figure 49 creating a sketch ................................................................................................................................ 63

Figure 50 using image pointing system to generate BMW 3 series model ....................................................... 63

Figure 51 importing the image .......................................................................................................................... 64

Figure 52 creating the constrained sketch ......................................................................................................... 64

Figure 53 creating the boundary walls for ANSYS ........................................................................................... 65

Figure 54 creating the boundary patch for boundary walls ............................................................................... 66

Figure 55 finishing the boundary patch ............................................................................................................. 66

Figure 56 Deck-lid model spoiler ...................................................................................................................... 70

Figure 57 ANSYS workbench ........................................................................................................................... 72

Figure 58 generating the named boundaries ...................................................................................................... 73

Figure 59 generating the named boundary and geometry condition in built-in the model ................................ 74

Figure 61 generating the boundaries for Open Spoiler model ........................................................................... 75

Figure 60 generating boundary conditions for deck-lid spoiler model .............................................................. 75

Figure 62 default mesh ...................................................................................................................................... 76

Figure 63 adjusting the mesh to 1 mm minimum and 2 mm maximum ............................................................ 76

Figure 64 Updated mesh of BLM ...................................................................................................................... 77

Figure 65 updated mesh of built-in model spoiler ............................................................................................. 77

Figure 66 updated mesh of deck-lid spoiler ...................................................................................................... 78

Figure 67 updated mesh for open spoiler .......................................................................................................... 78

Figure 68 Fluent setup ....................................................................................................................................... 79

Figure 69 applying the general settings ............................................................................................................. 80

Figure 70 changing the velocity formulation .................................................................................................... 81

Figure 71 adjusting the model settings .............................................................................................................. 82

Figure 72 adjusting the fluid selection .............................................................................................................. 82

Figure 73 assigning the input velocity (similar for all 4 cases) ......................................................................... 83

Figure 74 selecting the initialization ................................................................................................................. 83

Figure 75 selecting number of iterations for accuracy ...................................................................................... 84

Figure 76 shows converging the equations........................................................................................................ 85

Figure 77 showing the converged equations ..................................................................................................... 85

Figure 78 Velocity magnitude picture from Fluent ........................................................................................... 88

Figure 79 pressure contours ............................................................................................................................... 89

Figure 80 shows static pressure graph ............................................................................................................... 89

Figure 81 shows the stagnation point ................................................................................................................ 90

Figure 82 shows turbulence graph of the BMW Body and the tyres (in red) .................................................... 90

Figure 83 Velocity in X axis ............................................................................................................................. 91

Figure 84 Velocity magnitude in manufacturer’s –built in model .................................................................... 91

Figure 85 shows velocity in Y direction ............................................................................................................ 92

Figure 86 shows the pressure contours .............................................................................................................. 92

Figure 87 shows the static pressure graph ......................................................................................................... 93

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Figure 88 shows same stagnation region as the base line model ....................................................................... 93

Figure 89 shows the turbulence in case 2 .......................................................................................................... 94

Figure 90 shows the kinetic energy of the turbulence region ............................................................................ 95

Figure 91 shows velocity magnitude in deck-lid spoiler ................................................................................... 96

Figure 92 shows velocity in x direction ............................................................................................................ 96

Figure 93 enlarged picture showing the lesser velocity around the model ........................................................ 97

Figure 94 showing the pressure contours for deck-lid model ............................................................................ 97

Figure 95 showing the static pressure region in graph ...................................................................................... 98

Figure 96 shows turbulence in the deck-lid spoiler car ..................................................................................... 98

Figure 97 shows the velocity contours for open style spoiler model car ........................................................... 99

Figure 98 shows the velocity in x direction ....................................................................................................... 99

Figure 99 shows enlarged image of the velocity magnitude ........................................................................... 100

Figure 100 shows the pressure contours in open style spoiler model .............................................................. 100

Figure 101 shows the graph for the static pressure along with the geometry .................................................. 101

Figure 102 shows the turbulence contours for the open style spoiler model ................................................... 101

Figure 103 shows the velocity magnitude. From top to bottom Case 1, 2, 3, 4 respectively ......................... 102

Figure 104 shows the pressure contours for cases 1, 2, 3, 4 respectively........................................................ 104

Figure 105 shows the pressure graphs for cases 1, 2, 3, 4 respectively ........................................................... 105

Figure 106 shows the turbulence regions in cases 1, 2, 3, 4 respectively........................................................ 107

Figure 107 shows region of wake turbulence .................................................................................................. 108

Figure 108 figure of a deck-lid spoiler at rear of BMW 3 series. .................................................................... 111

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List of Tables:

Table 1 Upper body velocity magnitude for case 1, 2, 3, 4 ............................................................................. 103

Table 2 Lower body velocity magnitude for cases 1, 2, 3, 4 ........................................................................... 103

Table 3: Upper body pressure comparison for cases 1, 2, 3, 4 ....................................................................... 106

Table 4: Lower body pressure comparison for cases 1, 2, 3, 4........................................................................ 106

Table 5: Comparison table for turbulence in cases 1, 2, 3, 4 ........................................................................... 108

Table 6: Resultant forces on the model car body for cases 1, 2, 3, 4 .............................................................. 109

Table 7: Resultant forces from tyres for cases 1, 2, 3, 4.................................................................................. 109

Table 8: Total drag and lift forces in cases 1, 2, 3, 4 ....................................................................................... 110

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ABSTRACT

Performance, safety, manoeuvrability of a car depends on multi-disciplinary elements/ factors such as car

engine, tyres, aerodynamics, and ergonomics of design and most proficiently the driver. With the recent years,

inflation in the fuel prices & the demand to have reduced greenhouse emissions has played a significant role

in redefining the car aerodynamics. This concentrated on the utilization of negative lift called the down force

and resulting in several improvements. Aerodynamic drag created by the car results in the maximum fuel

consumption on highway, almost 50%. These aerodynamic properties are used to study the drag & stability of

car’s performance. Improvement in the aerodynamic drag can be achieved in multiple ways of introducing

active and passive air flow control. Rear spoilers are an example of the passive air flow control of the

aerodynamic drag. Generally rear spoilers are used to slower down the air flow and accumulate air which

helps increasing the pressure around the trunk and removing any chance of low pressure. The research

investigates on the effect of the rear spoiler in the aerodynamic drag, stability and efficiency. The research

focuses on 2D model of BMW 3 series sedan car with & without spoilers and the iterations of the rear spoilers

are designed in Auto desk inventor software. Modifications in the rear spoilers are done to obtain the minimal

drag and maximum downward force. The 2D surface model is extracted as CAD file with, without on the car

and individual rear spoilers are analysed on the CFD software ANSYS Fluent. The use of CFD software is to

calculate the estimated drag and lift values acting on the car as well as the drag force and the coefficient of lift

to improve the drag & stability. It involves understanding the basic applications of the post processing tools.

The results showed that the rear spoilers help in reducing drag by creating high pressure at the rear of the car.

Key Words: CFD, Fluent, Aerodynamics, Drag, Lift, Meshing, FVM, Inventor, Pressure, Velocity, Turbulence.

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NOMENCLATURE:

CD : Coefficient of drag

CL : Coefficient of Lift

CP : Coefficient of Pressure

P : Pressure

ρ : Density

v : Velocity

φ : Quantity

A : Area

m : Mass

𝛻 : Divergence

𝜕 : Partial Diffentiation

t : Time

ε : Epsilon

ω : Omega

Terms used:

CFD : Computational Fluid Dynamics

CAD : Computer Aided Engineering

BLM : Base Line Model

Free Stream : Stream line fluid flow

2D : Two dimensional object having length and breadth.

Variables relating to CFD results:

Drag Force : Component of force acting in the x direction

Lift Force : Component of force acting in the Y direction

Downforce : Negative of lift force.

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CHAPTER - 1

INTRODUCTION

15

1.1 PROJECT INTRODUCTION

The 20th century has seen some of the finest sedan cars. From highest speed Hennessey Venom GT

reaching up to 270.49 mph, Bugatti Veyron to the luxurious Rolls Royce phantom and much more. Personal

cars ranging from hatch backs, sedans & SUV have seen major changes in their design and ergonomics

depending on their customer’s choice. Aerodynamics for the cars has changed gradually from initial designers

to the manufacturers’ to obtain more power under the hood. This means more stability; better performance,

better grip and most prominently increase the comfort of the car. People seem to have sportier look to have the

best output performance. This certainly does mean that the cars are equipped with more additional parts such

as air dams, front and rear spoilers, and use of VGs (vortex generators) on the surface of the cars. Most widely

used are the rear spoilers in the passenger cars. This aids in greater drag reduction and in the same occasion

increases the stability of the car.

Mostly mounted on the car’s rear depending on the fixing location of the car rear (figure 1,3 ) either a

fastback, notch-back or square back. Spoilers can even be mounted in the front of the car as air dams with the

bumpers (figure 2). However rear spoilers provide the maximum contribution to the aerodynamic drag and

lift. This occurs as rear spoilers stagnant the flow of the air at the rear of the car generating a high pressure

region and reducing the low pressure. This directs the flow and offer greater drag reduction, increasing the

downward force at the rear and more stability.

Figure 1 Showing spoiler at the back of a sedan car

Figure 2 Front Spoiler on Maserati Figure 3 Open type rear spoiler

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1.2 PROBLEM BACKGROUND

Usually when a person drives the car, the car breaks through the barrier of the air. This creates a

region of high pressure as the air flows from the windscreen to the top surface of the car. Gradually there is a

region of the low pressure created at the rear of the car. In a worst case scenario, the air which possibly makes

way to the rear window creates a notch due to the window dropping down to the trunk, creates a region of

vacuum or low pressure which lifts the car and acts on the surface area of the trunk. This is possibly because

of the lack of the air being refilled in that region.

Technically a spoiler regulates the flow of air around the rear end by accumulating more air refill in

the region of the low pressure so that more high pressure region is created with better stability and the car

always sticks to the ground. Use of spoiler is quite unique and impressive as most of the sedan & hatch back

cars tends to become light at the rear end lifts the car while the spoilers help acting as an air barrier. This also

allows reducing the axle-lift and reduction of dirt in the rear surfaces of the car.

Figure 4 Flow of air around a car generating pressure areas & lift directions

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1.3 PROJECT AIM & OBJECTIVE

The research project aims to accumulate all possible information & Knowledge of a model car BMW

3 series sedan class aerodynamics focusing on the rear spoiler use. Aerodynamic forces can be used to

improve the tyre adhesive nature and find the vehicle performance. It describes the side slipping forces acting

on the tyre. Using three different types of the rear spoilers & their CFD analysis results to achieve the aim

using following objectives in the research project.

Analysis of the air flow around the car without the rear spoiler,.

Analysis of the air flow around the car with a concept rear spoiler.

Effect of the aerodynamics on the car

Analysis with the variation of the rear spoilers on the down force, drag and the stability of the car.

Estimating the CD (Coefficient of Drift) & CL (Coefficient of Lift) on a high speed run of the car.

Comparison of the CD and CL values with (variations in rear spoiler designs) and without rear spoilers.

Analysis of all the models on the CFD software ANSYS Fluent.

Drawing out the possible outcomes comparing the results & establishing the relation of using rear

spoilers for better performance, reduced lift and drag.

1.4 DISSERTATION DESCRIPTION

The dissertation report focuses on the investigation of the rear spoiler uses and its effect to the

aerodynamic drag, stability and lift as calculated by CD and CL. This obtained by a series of consecutive tests

and steps and research. The dissertation report starts with a literature review covering the basic standard

principles of aerodynamics which is easy to be understood by a layman. This is followed by theory which

focuses of the laws of physics and engineering of aerodynamics governing the equations and results. This also

includes the predominant theories and concepts used in the project.

As the title reflects Aerodynamics of a car using rear spoiler, a series of the CAD files are generated of the

different types of spoilers. This also includes the design of the model car with and without the rear spoiler

along with the spoilers. All the designs are generated on the Auto Desk Inventor 2014 as 2D surface. The

designs are exported as .iges or .step file to be extracted to the CFD package. ANSYS Fluent is used to run the

models for analysis. The CFD software interprets and results the value of CD & CL which is explained in the

18

observations & calculations. The obtained results are explained and plotted on a graph. Iteration of the

spoilers is compared to the base model.

Finally finishing the report with conclusion, future works are also included to underpin the potentials of the

further research that could be extended by potential candidates.

1.5 PROJECT SURVEY & OBSERVATION

According to a recent study (Stavros, 1995-2015) survey observation, a prominent feature was

observed that most of the passenger cars have started using spoilers with ranges from variation in their height.

Besides the research reports, surveys from different leading magazines like Car magazine UK, (Tim Pollard,

2015) and observing the inbuilt spoilers built by the car manufacturers were studied. It was found that there

were many different types of spoilers that could be used on the cars. Our study focuses on the fast sedan car

which has sufficient rear space to have the spoilers mounted on it. Since the fast sedan cars have rear boot

space called the notchback, spoilers like deck-lid and free standing spoilers can be used. This results in

eliminating the square hatchback car and hatchback spoilers. Most of the fast sedan car manufacturers provide

with deck-lid spoilers. This is usually done to minimize any errors during analysing.

Figure 6 Aftermarket deck lid spoiler Figure 5 Built-in spoiler

Figure 7 Different types of spoilers available in market.

19

1.6 PROJECT LIMITATION

One of the major limitations of the project was the system requirements. Most of the designs were

generated and simulated on a 4 core processor computer with 4 GB of ram. This underscored and limited the

designs to be in 2D surface models. As making in 3D would consume more memory power and the lab was

equipped with only above specification computers. Using 2D geometry has a major drawback as a restriction

of boundary. Other major dependencies were the designs were generated on the Auto Desk inventor

professional 2014. The researcher has previous knowledge of using auto desk inventor instead of the

designing geometry in ANSYS Fluent. This consumed a major time as modifications and iterations based on

the basic model, the researcher had to refer back to the initial models in the CAD format in inventor.

Although the project started with a delay in analysis, much of the major time loss was a result of the

initial geometry design and using ANSYS Fluent.

20

CHAPTER 2

LITERATURE REVIEW & THEORITICAL BACKGROUND

Figure 8 Wind tunnel test

Picture Courtesy: GTR Blog, 2015

21

2.1 LITERATURE REVIEW

The purpose of this chapter is to have a generic view on the background of spoilers in the automobile

industry. The evolution of the spoilers from a mere product to a must need requirement in the modern period.

Alongside with the changes, it also describes the basic concepts and theories of aerodynamics that play a

crucial role in the research.

It all started in late 1890. The earliest design of a car based on the concepts of aerodynamics was made by

Camille Jenatzy, a Belgium race car driver (Dimitris, 2007). This was followed by a conceptual design by

Alfa Romeo in 1914. The car was “La Bomba” which was an aerodynamically designed but failed because of

world war era and its weird design (Altecc, 2001-2015)

After the post-world war era the concept of the aerodynamics on the cars were more focused. Number of

concept designs was analysed. This resulted in water dropped shaped cars as, water drops were considered to

be aerodynamically perfect (Patrascu, 2011).

Figure 11 Water drop shape

Figure 10 Dimitris first aerodynamic car design Figure 9 Failed La Bomba car.

Figure 12 Water drop shaped car Persu

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In the same era, Germany played an active role in understanding the aerodynamics involved in a car. Infact

Germany was forbidden in building aircrafts after the war. This led the aerodyamic engineers to convert their

aero ideas into cars and make it an aeronautical flavored (World War planes, 2001).

Edmund Rumpler an Viennese pioneer in aerodynamics in cars tested the first car in wind tunnel. The car he

tested was Trophenwagen which showed a drag of about 1/3rd

of the contenporary vechiles. In the same

period Paul Jaray, an Austo-Hungarian designer well know for his aerodynamic and streamline design of cars.

He innovated the smooth surfaces of the body of the car, headlamps and cambered windsheilds. Much of his

work were copied or adopted in big car manufacturing players like BMW, Mercedes, Audi, Diamler-Benz

(Dimitris, 2007). However the streamline shaped cars were never a hit since they generated a high drag

cofficient of around 0.4. Some of the streamline designs still in use are like Porsche 911, Vokswagen Beetle.

In early 1970’s the crisis for petrol and more efficiency resulted in Kammback cars. Wunibald Kamm an aero-

dynamist from Germany brought the concept of aerodynamics in cars, which was the use of air foils. He

showed that the air foils with slight truncated tailing edge have slightly lesser drag coefficient compared to

completely air foil shaped cars. The post-world war 2 era saw a drastic change in the automobile shapes from

brick designs to rain drop and streamline shapes.

Figure 14 Volkswagen Beetle Figure 13 Porsche 911 streamline car

Figure 15 Coefficient of drag value of cars

changing over decade

23

All these changes in the car designs were the result of the detailed optimization of the drag improvement in

1970s. It was based on the numerous minor and major modifications in the drag reductions. Detail

optimization included the modifications in curvatures, pillars, location of spoilers and much more but reached

it limits quiet early. Some of the failure example was Opel’s GT which had a drag coefficient of 0.42 even

with streamline design and spoiler.

Figure 16 Opel's GT a failure model with spoiler

Even yet the detail optimization resulted in the dramatic change but the prior concentration of the car

manufacturers was in the reduction of the drag. By this time, shape optimization was given more priority. Re-

evaluation of work by the aero dynamists from early 1930s was conducted. This led to a realistic car design

and shape with lower drag coefficient. Audi 100 was the first manufactured which a drag coefficient of 0.3

(Edgar, 2006).

Current State of Art

The current state of art in aerodynamics utilizes both the detail and the shape optimization.

The reasonable drag coefficient can vary from 0.25 to 0.35 for modern cars.

For future aspects and reasonable target a drag coefficient of 0.25 is idealistic.

The evolution of the car spoilers involved use of general concepts & theories of physics. These were flow of

air around the streamlined body, effect of the pressure, way the air as a fluid acts when the car is in motion

and much more. It is hence very important to discuss them in brief to get a clearer view of the working science

behind the aerodynamic product spoiler and the car. From the aircrafts to the cars, the aerodynamicists have

invested a mixture of aeronautics in cars that has resulted in more efficient models. Much of the credit in the

24

research work of the evolution is involved in experimental coherence with the laws of physics and

computational analysis.

2.2 GENERAL CONCEPTS

To provide a clear view to the literature review, the whole literature review has been sub categorized

into different parts. Each part defines & makes the concepts of the theory easier to be understood.

2.2.1 LIFT CONCEPT

In aerodynamics lift (figure 17) is a force that holds an object in the air. In automobiles the pressure

difference of the high pressured frontal end to the low pressure rear end generates the lift.

But how actually it is generated with velocity?

The answer lies in simple physics. Whenever air flows over an object or vice versa, the molecules of the gas

move freely. According to David Bernoulli (Bernoulli’s concept explained: 2.1.*) the pressure is directly

proportional and relates to the local velocity of the air (NASA, 2013). This explains why velocity varies and

pressure too. Lift is always perpendicular to the flow of the air on the automobiles. It is explained by the

following equation in aerodynamics:

𝑳𝑫 =𝟏

𝟐𝛒𝐯𝟐𝑪𝒍𝑨 Equation 1

Where 𝑳𝑫 is the Lift force

𝛒 is the density of the fluid.

v speed of the object

CL is the lift Coffieicient

A is the cross sectional area.

This equation will be used further in the chapter of results to find the lift force obtained in the car body.

Generally the lift force will be the total force of the forces in y direction in addition to the viscous forces in the

y direction.

25

2.2.2 DRAG CONCEPT

Drag in general physics is referred or defined as the resistive force experienced by an object/ body

when it is in motion with respect to the fluid surrounding it. Drag forces are dependent on the velocity of the

object and is shown by a formula defined as:

𝑭𝑫 =𝟏

𝟐𝛒𝐯𝟐𝑪𝑫𝑨 Equation 2

Where FD is the drag force

𝛒 is the density of the fluid

v is the speed of the object in the fluid

CD is the drag Coffieicient

A is the cross sectional area

Drag force is highly dependent on the density of the fluid, velocity of the object and cross sectional area of the

body acting with the fluid. This means the sleeker the body is less the drag coefficient (which is a

dimensionless value) less is the drag force is. However the velocity and density is also proportional to the drag

force. This will be used to calculate the net force acting on the x direction on the car body along with the

viscous forces.

Figure 17 shows the direction of flow, Lift and drag

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2.2.3 BERNOULLI’S EQUATION

𝐏 +𝟏

𝟐𝛒𝐯𝟐 + 𝛒𝐠𝐡 = 𝐂𝐨𝐧𝐬𝐭𝐚𝐧𝐭 Equation 3

The Swiss mathematician & physicist (1700 – 1782) put forward a principle called Bernoulli’s equation (Eqn

3) which held for fluids in ideal state; pressure and density are inversely related: in other terms slowing

moving fluids exert more pressure than fast moving fluids. This equation is the fundamentals of the study of

the airflow around vehicles.

Bernoulli’s equation obtained by integrating Newton’s law F = ma (Munson, Young, and Okishi.

2006) is supported with the following assumptions:

Air density does not change with the pressure.

Viscous flow of the fluid is neglected.

Steady state flow is assumed and always maintained.

The fluid flow is compressible.

The formula can be applied at any point in the streamline flow.

This resulted in the formula being derived to

𝐏 +𝟏

𝟐𝛒𝐯𝟐 + γz = Constant Equation 4 (Munson 2006)

Or can be written as

𝐏

𝛒+

𝟏

𝟐𝐯𝟐 = 𝒌 Equation 5 (Katz 1995)

The above equation is valid when height is not accountable.

Region of Low pressure Region of high pressure.

Figure 18 Flow of air/ fluid around a spherical body to demonstrate low and high pressure regions

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Whenever the air flows over the body, it generates a velocity distribution resulting in the aerodynamic loads

acting on the body of the vehicle. The first is the shear force acting tangentially on the surface of the vehicle

body generating the drag force which is because of the viscous boundary layer. The second force is the

pressure force. The pressure force acts perpendicular to the surface of the body and has a contribution to both

drag and lift. Technically the vehicle’s downforce is the added effect of the pressure distribution (Katz, 1995)

Application in the research model:

As the model car/ car pass through a region of fluid, velocity changes with the geometry. This means the

geometry will have regions of high velocity and low pressure or vice versa. This is established by the equation

3, that when pressure is maximum, the velocity is zero as they equate to constant and vice versa.

Figure 19 a.) Left shows the low pressure. b) Values of coefficient of pressure around the geometry

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2.3 AERODYNAMIC FORCES

2.3.1 DRAG FORCE

As already explained in 2.2.2 drag force opposes the motion of the car which is travelling. This

ultimately affects performance of the car, fuel economy as well as greater power is required to overcome the

force. As usually given by the expression in which is

𝑭𝑫 =𝟏

𝟐𝛒𝐯𝟐𝑪𝑫𝑨

A: “A” is the frontal area in square of meter (m2). The size of vehicle is directly related to the drag properties

and is characterised by the value of CDA. However the frontal area is slightly less than the total width &

length of the car measured in (m2)

CD: Coefficient of Drag is a function of Shape, Reynold number (Re), Mach number (Ma), Froude number

(Fr) and relative roughness ε/l and is given mathematically by:

CD = Ø (Re, Ma, Fr, ε/l) (Munson, 2006)

The density of the air ρ is dependent on the temperature, humidity, altitude and pressure. On in any standard

condition the density of the air is 1.23 kg/m3. Any change in the pressure is denoted by PX and temperature by

TX using the equation to find the density ρ (Gillespie, 1995).

𝛒 = 𝟏. 𝟐𝟐𝟓 [(𝑷𝑿

𝟏𝟎𝟏.𝟑𝟐𝟓) (

𝟐𝟖𝟖.𝟏𝟔

𝟐𝟕𝟑.𝟏𝟔+𝑻𝒙)]

In the eqn [ ] the term 1

2ρv2 is the dynamic pressure of the air and v is the final velocity of the car.

2.2.2 LIFT FORCE

With the Drag force there is one more component of the force called the Lift force which tends lift the

car and reduces the friction between the tyres and the road. This means the force acts as the stability of the car

and handling too. Given by the eqn 1, i.e. 𝑳 =𝟏

𝟐𝛒𝐯𝟐𝑪𝑳𝑨 , lift force plays a significant role in the

aerodynamic optimization of the car.

29

The lift force is a dependent on the shape of the car. In the present modern day passenger cars, the coefficient

of lift ranges from 0.3 – 0.5 for any wind angle at zero degrees (Huco, 1998). However in crosswind

conditions the value of CL can vary from 1 and increases on.

This clears that even L is a function of geometry i.e. Ø (geometry).

2.3.3 DOWNFORCE

The force that is exerted on to the car by the aerodynamic properties of the rear spoiler is called the

downforce. This actually follows Newton’s third law. Every action has equal and opposite reaction. Hence the

downforce is the opposite force to the lift and is usually greater. The downforce is responsible for the car to

keep on to the track and provide more traction to the wheels.

Downforce is usually generated when air mover through and over the parts of the car (Fig ). This occurs when

the wing pans are set at angle which forces the air up and through it naturally generating a force downwards –

or the opposite force. The positive aspect of having a downforce is that since it adds traction to the wheel, it

also adds more stability to the car.

The down force can be given by the formula (T. Glossop, S. Jinks, R. Hopton, 2011):

𝑭𝒘𝒊𝒏𝒈 =𝟏

𝟐(𝑾𝑯𝑨𝒐𝑨)(𝑪𝑫𝝆𝒗𝟐) Equation 6

Figure 20 shows downforce generated due to spoiler.

30

Where Fwing is downforce per wing

W is the wing span

H is the height of the spoiler.

AoA is the angle of attack.

CD is the coefficient of drag

𝝆 Is the density

𝒗𝟐Is the velocity, squared.

However the equation can be simplified as ß the effective area of each wing.


𝟐(𝑨𝒐𝑨)(𝑪𝑫𝝆𝒗𝟐)ß Equation 7

With the number of the spoilers (front & rear usually ranging from 3 to 5 this equation changes to


𝟐(𝑨𝒐𝑨)(𝑪𝑫𝝆𝒗𝟐)(ß𝟏 + ß𝟐 + ß𝒏) Equation 8

2.4 AERODYNAMIC PRESSURE DISTRIBUTION

As the car moves through an ambient mass of air, the body of the car displaces bundle of imaginary

streamline filaments that constituent of the airflow field. Now as the stream line is displaced these streamlines

are made to accelerate from rest up to a velocity. This creates a pressure distribution across the air field and

the boundary of the body of the car (fig 22 ). The high static pressure also referred as the zero velocity is

Figure 21 shows airflow in profile for the Nissan R35 GTR

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generally the stagnation point in the front of the car while the low static pressure area is the wind screen

header and the top roof peak of the car. (John D. Smidth, 2014)

The coefficient of pressure at any point on the surface of the car is characterised by the following equation

given by: 𝑪𝒑 =(𝐩−𝐩𝟎)

(𝟏

𝟐𝝆𝒗𝟐)

[Eqn ] where Cp is the coefficient of pressure, p is the static pressure at the

vehicle surface, p0 is the free stream static pressure and rest of the variables are defined earlier.

Usually the value of Cp at the stagnation point is 1 & zero when the local as well as free static pressure is

same all over the flat section of the car body. The negative pressure coefficients can be obtained in certain

cases when the local velocities are greater than the free stream velocities.

The coefficient of the pressure depends upon the geometry of the car, hence is a function of the shape. The

distribution of pressure on most of the surface of the car is done by using Bernoulli’s equation [Eq. ]. The net

upward force is calculated by the integration of the total pressure distribution. The force obtained (Which is

usually negative) means that there is no requirement to enhance the stability of the car. The exact opposite

reactive force is the downforce (explained in 2.2.3) (Duysinx, 2014-2015)

Certain experiments on the pressure distribution calculated by different car manufactures and individual

research analyses are shown below. This will help to generate a clear concept of the pressure distribution

around a car.

Region of stagnation

Region of low pressure Corvette

Stingray.

Figure 22 shows region of high (blue) & low (yellow) pressure of a corvette Stingray

32

Figure 23 Pressure Coefficients Plotted Normal to surface

Figure 24 Region of high & low pressure around a car

33

Figure 25 Variation of Cp along with the geometry

Figure 26 shows the region of high & low pressure along with the car geometry.

34

Application in the research work:

We will further use this to find the coefficient of pressure in different models of the BMW 3 series model car.

The use of the pressure distribution will be important to understand the region of the high concentration of

pressure and low concentration along the geometry of the model car. Apart from the pressure distribution, this

topic will help in establishing the concept of topic 2.2.3.

2.5 RELATION BETWEEN COFFICIENTS OF DRAG & LIFT

Before we study and the application of the coefficient

From an experimental study of a generic car, it was concluded that the coefficients of drag and lift for the flow

around the body of the car is predominantly dependent on the slant angle. It was observed with the generic

model that from 0o to 29

o the growth of the lift is linear and drastically changes to negative when the angle

reaches 30o. The drag coefficient is minimum at angle of 15

o which means the lift coefficient is close to zero

and becomes 50% greater when the slant angle reaches 29o.

However beyond the slant angle of 30o the lift and drag becomes nearly constant. (Ivan Dobrev, Fawaz

Massouh, 2014).

Coefficient of Drag is given by: CD = 𝑭𝒅

(𝟏

𝟐𝛒𝐯𝟐𝑨)

⁄ Equation 9

Coefficient of Lift is given by: CL= 𝑭𝑳

(𝟏

𝟐𝛒𝐯𝟐𝑨)

⁄ Equation 10

Both CD and CL are dimensionless values.

2.6 AERODYNAMIC PRODUCT - REAR SPOILERS

The aerodynamic product spoilers are devices that increase the stability of the car, reduce the drag and

regulate the pressure difference resulting in the better performance of the car. The spoilers constitute of the

front and the rear spoilers. However the rear spoilers contribute to a major aerodynamic stability of the car

(Xu-xia Hu, 2011). The aerodynamic devices – rear spoilers acts as a diffuser. Usually mounted on the top

surface of the rear trunk to create/ generate pressure difference (explained in 2.3). Rear spoilers provide the

following advantages.

35

Increases the tires capability to produce the required forces.

Offering stability at a very high speed.

Better traction generating fuel efficiency

Improves braking performance.

2.6.1 HEIGHT OF REAR SPOLIERS

The way in which drag and lift happened is depend on the height of the spoiler. The influence on the

pressure distribution is shown below. The possibility of reducing drag is comparatively low. In fact on sporty

cars, and even more so on racing cars, even an increase in drag is accepted in order to ensure that the rear-axle

lift gets low.

Figure 28 Variance of pressure coefficient along

a.) angle of application b) with spoiler height

Figure 27 Gillespie experiment of how height of spoiler affects the pressure.

36

The extended rear spoiler can increase the pressure on hatch; as a result, rear axle lift is reduced about a third.

Figure shows how a rear spoiler influences in reducing lift force at rear. The spoiler causes a clear rise in

pressure on the rear slope in front of it. If the pressure is plotted versus the vehicle’s z/h for the centre

cross section, the reduction in drag is obvious

Figure 29 Pressure coefficient along the front end and

rear end with & without spoiler

Figure 31 shows different mounting of the rear spoilers

affect the Lift and the Drag coffieicient value

Figure 30 shows values change when spoiler

retracts and in action

37

The relation between the spoiler height, lift and drag follows a linear predictable trend obtained from a

research work on BMW sport 6 series at Johannesburg (Aberu, 2013). Increasing the spoiler height further

slows down the flow field passing over the roof line reducing the dynamic pressure drop to decrease the total

lift.

2.7 CONTINUTY EQUATION

According to the law of conservation, it can be stated that the mass can neither be created nor be destroyed.

This law can be used in the steady flow process which means that there is no change in the flow rate with time

through a control volume when the stored mass of the control does not change. (Engineering Tool, 2014)

This means inflow is equal to the outflow.

The equation for the continuity equation can be shown as:

m = ρi1 vi1 Ai1 + ρi2 vi2 Ai2 + ρin vin Aim

= ρo1 vo1 Ao1 + ρo2 vo2 Ao2 + ρom vom Aom

Equation 11

Where:

m = mass flow rate (kg/s)

ρ = density (kg/m3)

v = speed (m/s)

A = area (m2)

With uniform density equation (1) can be modified to

q = vi1 Ai1 + vi2 Ai2 +vin Aim

= vo1 Ao1 + vo2 Ao2 + vom Aom (2)

Where:

q = flow rate (m3/s)

ρi1 = ρi2 = ρin = ρo1 = ρo2 = ρom

Figure 32 Body used to show equation of continuity

38

Application in the research:

For all flows, FLUENT solves conservation equations for mass and momentum. For flows involving heat

transfer or compressibility, an additional equation for energy conservation is solved. For flows involving

species mixing or reactions, a species conservation equation is solved or, if the non-premixed combustion

model is used, conservation equations for the mixture fraction and its variance are solved. Additional transport

equations are also solved when the flow is turbulent (figure 33).

Figure 33 showing the use of continuity in ANSYS Fluent

Now since we will use the model of an original car, we will obtain the results for the model. To compare the

model with the original car, the easiest and the fastest way is dimensionally analyse the model and the car.

This will help in obtaining the values for the original car. Let’s discuss dimensional analysis and similitude in

brief.

2.8 NAVIER STOKES EQUATION

The Navier Stokes equation provides the foundation for fluids in motion. It is one more important

topic along with equation of continuity. It is important to discuss Navier Stokes equation as it forms the base

of the analysis if the fluid flows in CFD. Fluid has no limits for distortion when forces are applied. This means

that the fluid goes through number of forces. To simplify Navier derived an equation for the viscous fluid

Stokes slightly modified the equation to form a basic equation called Navier-Stokes equation:

39

The easy way to remember Navier Stokes equation is by understanding the concept1. The whole process is

categorised into following three sections:

Transient

Convection

Diffusion.

Transient: It refers to the rate of change of the quantity in an infinite volume for a temporary time. Assuming

φ is any random physical quantity like mass, pressure, density, temperature or any other factor. Hence

mathematically transient process can be defined as

𝜕𝜌φ

𝜕𝑡

Convection: If there is any presence of the velocity within the field, the quantity is transported. This is

defined as the convection method and is the first derivative multiplied by the velocity. Mathematically

represented as

𝛻. (𝝆𝒖𝛗)

Diffusion: It refers to the transport of the quantity due to the presence of gradients of that quantity. It is

referred in the mathematical terms as

𝛻. λ𝛻𝛗

Where λ refers to the diffusion constant. This is equal to the thermal conductivity in the heat transfer.

Finally all the three equations are combined to obtain an accumulated equation referred to general transport

equation shown as

. Transient + Convection = Diffusion + Source

𝜕𝜌φ

𝜕𝑡+ 𝛻. (𝝆𝒖𝛗) = 𝛻. λ𝛻𝛗 + 𝑆𝑜𝑢𝑟𝑐𝑒𝛗

When obtaining the equation of continuity it can be said that 𝛗 is 1 (for compressible flows). When the

diffusion is not present and absence of the source all the terms can be set to 0.

𝜕𝜌

𝜕𝑡+ 𝛻. (𝝆𝒖) = 0

To obtain the Navier Stokes equation the physical factor φ can be replaced by the velocity component at the

time t. This represents the Navier Stokes equation as:

1 Shown in Patankar’s brief for understanding Navier Stokes Equation.

40

𝜕𝜌𝑢

𝜕𝑡+ 𝛻. (𝝆𝒖𝑢) = 𝛻. 𝜇𝛻𝑢 −

𝜕𝜌

𝜕𝑥+ 𝜌𝑔𝑥 Equation 12

Similarly in the equation if u is replaced by v and w for y and z coordinates’.


In the ANSYS Fluent, the software that will be used to analyse the results in CFD, uses Navier Stokes

equations in the final volume discretization method. This equation provides a filtering operation. Mainly used

in the mesh grid sizing and grid spacing. This largely affects the mesh quality too. The background of the

meshing runs the Navier Stokes equations as in form of Fourier series to obtain a high quality mesh.

The literature review focused on the background history of the research product – spoilers along with the basic

laws & concepts of physics and aerodynamics acting on the product. This helped to give a depth idea of the

mechanism of the spoiler and how these laws still govern the digital analysis for the product.

The next chapter introduces and familiarizes with the use of different methods for comparative analysis and

introduces CFD.

2.9 DIMENSIONAL ANALYSIS & SIMILITUDE

Generally very few real flows can be solved by analytical methods. It requires huge laboratories and

more consumption of energy to run a wind tunnel as for example in this research project. Generating huge

forces in the wind tunnel can alone consume electricity of an entire village. As a result alternately, models of

the prototypes are generated and tested. This means the models and the prototypes need to match certain

criteria which are geometrical similarity and kinematic similarity. Satisfying the above mentioned criteria

results in dynamic similarity which means the results of the model can be equated to the prototype to find the

results of the forces in the prototype.


In the research results we will try to dimensionally analyse and similitude the actual value of the force in the

car from the obtained values of the model. There will be a limitation since, the model being used in the

research work is 2D has limitation on the results as they would have absence of forces in z coordinates.

41

CHAPTER 3

METHODOLOGY

Figure 34 Wind Tunnel test of spoiler on Porsche 911 Carrera

Picture Courtesy: website Pressebox.

42

3.1 INTRODUCTION

The research focuses on the application of the rear spoilers on the personal cars. Hence it was

important to discuss the vital aspects of the aerodynamics involved in the car and the effect of the spoilers on

the aerodynamics of the car in the literature review. The research work is meant to be aerodynamics of a rear

spoiler on a car in two dimension using Computational Fluid Dynamics software to analyse the results.

Throughout the research work there will be application of two approaches to compare and illustrate the

results. It is important to have an appropriate methodology of both qualitative and quantitative methodology to

obtain the final result.

3.1.1 QUALITATIVE VS. QUANTITATIVE: QUESTIONS & APPROACH

When compared to both qualitative and quantitative research work both methodology enquires &

implements statements of philosophy, enquiring strategies, surveying to collect the data, analysing and

interpreting the results. Qualitative approach emphasises on the essence and the ambience of the entities of the

research work. Putting the statement in other way means that qualitative approach focuses on the quality,

intensity of the matter, and amount that cannot be experimentally determined. This means that the

concentration is led on to the concepts, theories, metaphors, symbols and description. The research statement

often stressed on how socio – economic experience is obtained by giving a meaningful name to the research

work. The quantitative methodology on the other hand focuses on the analytical approach, statistics and data,

use of the numerical methods to interpret the research and approach the results with validation. This includes

the use of different numerical software to calculate the values and document the research work for future use.

Qualitative Methods:

Quantitative method is the narrative way to explain the research work. This includes the theories, concepts

implications in everyday applications, decontructivism, phenomenon, past research, industry practice,

standards, implications, explore processes, the cultural studies, market research, products descriptions and

implementations. The researcher focuses on the best methods to draw the results for the research work.

Coherence of qualitative method in the research work:

The research work on aerodynamics of a rear spoiler on a car in two dimension using Computational Fluid

Dynamics software to analyse the results has explained the main qualitative methods. The entire research

work focuses on the use of the spoiler by the automotive industry from market point of research to the

43

factual reasons of using the product. Chapter 1 introduces the research project, and supports the socio

economic need for the product in the modern automotive industry, ways to design and analyse the product

as well as the project limitation. This is followed by Chapter 2, which emphasizes on the history of the

spoiler to evolution and practical implementation as a literature review & the general concepts and

theories of fluid dynamics working behind the product. The method of qualitative analysis is not only

restricted to the first two chapters instead it follows with the market survey and data collection of

applications of most used spoiler in industry and after market in chapter 3 as well as comparing the

obtained results with the quantitative methods.

Quantitative Methods:

The quantitative method is more independent of the qualitative method. This implies that the researcher

has greater influence on the qualitative method. Quantitative method focuses on the application of

techniques to solve the problem statement of the project, conducting the research with different software

tools, illustrating the results, documenting the results, comparing with the historiography and stating the

conclusions.

Coherence of qualitative method in the research work:

The research uses more quantitative method to find the solutions. This focuses on the use of designing

software for the BLM and spoiler designs, using different methods of flow simulation, explaining the use

of ANSYS Fluent, comparing the methods of numerical flow analysis, importance of meshing and

selection the method, validating the simulation results and comparing it with the qualitative methods.

Each method has advantages and limitations depending on the level of illustration, opportunity to review the

collection process, proximity to obtained values and amount of biased based on the researcher.

The next topic discuses on the CFD in general.

44

3.2 ENGINEERING DETERMINING METHODS

Engineers have always been interested in understanding and predicting the behaviour of fluid flow

system behaviour & variables. There are three way of predicting methods which are included below:

Figure 35 Pie chart showing the three different methods of prediction

3.2.1 EXPERIMENTAL METHOD:

The most reliable and easiest way to predict the natural phenomenon is usually done by gathering the

information about the measurements. This is the common way of gathering the information of the full scale

equipment and predicts how the equipment would behave in real life application.

Pros:

The actual model can be used for the experimental analysis for prediction.

Accurate results can be used to understand the phenomenon

This method plays an important role in deriving the statistics and data for future use.

Cons:

Sometimes the actual equipment costs too much. This can be expensive method to apply in large

applications like in aeronautics or automobile industry.

Experimental Method

Analytical / Mathametical

Methods

Numerical Methods

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This method of using actually collecting the information can result time loss as rigorous experiments

needs to be conducted to find the minute changes.

Application: In small scale product development, in using the past data for future design and development.

Examples include: Aeroplanes.

3.2.2 ANALYTICAL METHOD:

This method works on the consequences of the mathematical model. These mathematical models

describe the behaviour of the system. Usually the mathematical model is a set of differential equations which

are used to solve the problem.

Pros:

Use of pre-set/ pre-defined differential equations

These methods help engineers’ fundamentals of controlling and behaviour of engineering systems.

Cons:

Limitations of validity of the solutions if too many assumptions and simplifications are made.

3.2.3 NUMERICAL METHOD:

It use the to find the behaviour of the physical properties on the product using set of defined

differential equations by means of digital computing. It uses the physical properties of the product from the

experimental data and pre-defined set of differential equations to understand the behaviours and effects. It

breaks the problem into discrete parts where it uses set of equations on each discrete part.

Numerical method can be classified into three categories of discretization methods to understand the meshing:

1. Finite Difference Method:

This is the simplest procedure used to derive the discrete form of differential equations. The finite

difference method uses Taylor series using approximate derivatives. It is the simplest form to apply

differential equations on the uniform grids.

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2. Finite Element Method:

This method was developed at the time of 1960, especially to analyse the structural dynamics

problems. In other terms is based on the weigh residual method. This is a beneficial over the

difference method as it can handle complex geometries and use arbitraries on irregular shapes.

3. Finite Volume Method:

The Finite Volume Method (FVM) is one of the most robust discretization techniques used in CFD.

FVM usually divides the domain into small control volumes (cells, elements) where the variable of

interest is located at the centroid of the control volume. The next part is that it integrates the

differential form of the governing equations (very similar to the control volume approach) over each

control volume using interpolation. The resulting equation that is derive is discretized or discretization

equation. In this manner, the discretization equation expresses the conservation principle for the

variable inside the control volume.

The most prominent feature of the FVM is that the resulting solution satisfies the conservation of

quantities such as mass, momentum, energy, and species. This is exactly satisfied for any control

volume as well as for the whole computational domain and for any number of control volumes.

FVM is the ideal method for computing discontinuous solutions arising in compressible flows. FVM

is also preferred while solving partial differential equations containing discontinuous coefficients.

Use in the research work:

The finite volume method is widely used in the generation of mesh (described below) in ANSYS

Fluent. The research focuses on the behavioural properties of a rear spoiler in air. Hence FVM is the

only method to be used for it.

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3.3 COMPUTATIONAL FLUID DYNAMICS

3.3.1 INTRODUCTION TO CFD

Fluids (gasses and liquid) are governed by partial equations that represent the general laws of

conservation of mass, momentum and energy. CFD is the art of replacing such PDE by set of equations which

can be solved by the digital computers (Kuzmin, 2013).

Computational Fluid Dynamics (CFD) provides quantitative and qualitative predictions of the fluid flow by

means of the following:

Modelling by applications of mathematics of partial differential equations

Use of discretion and solution tools i.e. numerical methods.

Use of the software tools like solvers, pre and postprocessing utilities.

CFD is essential software which enables the engineers to virtually simulate the numerical experiments carried

in the laboratories resulting in less time consuming process and better accurate results. CFD gives an insight

to the pattern of the fluid flow that is difficult to predict with regular experiments, expensive to conduct and

sometimes impossible to study by the regular experiments.

3.3.2 HOW DOES CFD MAKE PREDICTIONS?

The CFD software use mathematical tools to solve the problem which is a pre-set of equations. The

main factor of CFD is

The researcher who feeds the problem into the computer

Scientific knowledge that is expressed mathematically.

The computer code that consists of the algorithms that embodies the knowledge

Hardware of the computer that performs the calculations

The researcher who simulates and interprets the data

CFD is a highly disciplinary subject that indulges into the research area and lies at the interface of physics,

applied maths and computer science.

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3.3.3 CFD ANALYSIS PROCESS

CFD analysis process can be summarised in the following steps:

1. Problem Statement:

It deals with the problem statement of the problem and the fastest way to achieve it.

It also includes the physical phenomenon to be taken in considerations.

Operating conditions and the geometry of the body.

Type of fluid flow i.e. Laminar/ Turbulent/ Multiphase.

Objective of the CFD analysis i.e. in this research case will be the drag, lift and

downforce.

2. Mathematical Model:

Defining the symmetries and the flow view.

Defining the computational domain.

Formulating the law of conservation of mass, energy and momentum

3. Discretization Process

It includes the mesh generations, sizing of mesh and inflation

Changing the mesh structures.

Time discretization

Space discretization

4. CFD Simulation

Generating the simulation.

Changing the quality of the simulation

5. Post Processing and Analysis

It is the method of extracting required results from the computation flow field.

Visualization and debugging of CFD model.

Validation of the CFD model.

Using systematic data analysis by means of statistical tools.

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6. Uncertainty and errors

Uncertainty includes the lack of knowledge specially the turbulence.

Acknowledging the local and the global errors.

7. Validation of the CFD models.

Trying different models or iterations with the boundary and geometric conditions.

Documenting the findings in report.

Assessing the uncertainty and errors by performing sensitivity analysis and

parametric study.

8. Validation of CFD Codes

Examining the computer program by visually checking it and documenting it

Checking the consistency of the trial.

Cross checking the results obtained with analytical results.

3.3.4 MESHING

Usually the discretion process converts every continuous system to a discrete one. This means that the

grids or the mesh generation is done to obtain the approx. solution at each discrete grid.

Grid generation of mesh is either of the two types.

1. Structured Mesh generation

2. Unstructured mesh generation

1. Structured mesh generation:

Mesh is generated to fit on the boundaries. The benefit of having structured mesh is to generate the

high and good quality of mesh. This regulates the fastening go the solution algorithm. It is difficult to

have complex domains in mapping from a rectangular grid. Generating the grid is followed by the

physical problem discretion and solved on that grid. The most useful method is to convert the

equations in to the model problem of computational space (figure 36)

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a. Algebraic grid generation:

Algebraic grid generation is called transfinite interpolation. This method uses the interpolation value

from the boundaries of the computational domain. This can be a beneficial for the grid/mesh density

also in assigning one to one mapping.

However this method generates singularity corner into interior of the domain.

b. PDE Mesh generation:

This method enables the generation of the regular mesh & higher accuracy. There is a single a single

value relationship between the generalised coordinates and simple coordinates. Since the model of

the car in this research project is in 2 dimensional, it will easier to explain.

There is a single value relationship between the generalised coordinates and the simple coordinates.

It can be explained as

ε =ε (x,y) n=n(x,y)

i.e.

x=x (ε,n) y=y( ε,n)

Figure 37 mapping of the physical coordinates on the x, y coordinates.

Usually the functional relationships are determined by the mesh generation process and converted to

the governing equations.

Figure 36 shows a fine structured mesh on a model

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Conclusion:

This method dominated the CFD methods in the early developed codes. It required more computational

storage. The old fashioned was replaced by the unstructured mesh generation which generated mesh more

automated fashion and is more accurate to determine for the complex geometries.

2. Unstructured mesh generation:

They were initially created for the finite element discretion method. However for the variety of applications

available in the finite volume discretion they are used in meshing the fluid domain. In the finite volume

unstructured meshing there are large possibilities of different mesh sizes ranging from triangles, square in 2D

to the prisms, tetrahedral and bricks (figure 38). The instructed meshing in the final volume discretion follows

mainly four different methods of mesh/ grid generations. These four different methods follow a basic set of

rules mentioned below:

1. Generation of the valid mesh. This means that the mesh should have no holes or self-intersection.

2. Conformation of the mesh with the boundary.

3. Balancing the density of the mesh to control the accuracy and computational requirements.

Figure 38 Generation of unstructured mesh of BMW 3 series model.

The popular methods to generate finite volume meshing in CFD are:

1. Surface Meshing

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2. Advancing front method

3. Delaunay triangulation method

4. Other methods like paving & plastering, Octree and semi unstructured mesh generation.

Application in the research methodology:

Automatic unstructured meshing has been used in the mesh generation. However the mesh sizes have been

defined to as low values approx. – 1 mm to 2 mm (fig 39, 40) to increase the mesh quantity and quality for

better accuracy in results.

Figure 39 adjusting the element sizes and finding the number of elements

Figure 40 Meshing of the model with minimum 2 & maximum 4 mm element size

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3.3.5 MESH QUALITY

Mesh quality plays a crucial role in the determination of the accuracy of the results, irrespective of the

types of mesh being used.

1. Mesh Element Distribution:

It is important to have a fine mesh element distribution. Since the domain is discretely defined, the salient

features of the fluid flow depend on the mesh density and distribution. The mesh distribution in the research is

fine and uniform. The automated mesh generated is further modified by the researcher (fig 41, 42).

Figure 42 meshing obtained adjusting sizing

Figure 41 meshing with default configurations

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2. Cell Quality:

It depends on the skewness and aspect ratio. Skewness is defined as the difference between the shape of the

cell and shape of the equilateral cell of equivalent volume while aspect ratio is the measure of stretching the

cell. In a general rule for a good mesh is to have the triangular mesh with skewness less than 0.95

3.3.6 BOUNDARY CONDITIONS

Boundary conditions serve the important and most required conditions for the mathematical model

(Bakker, 2002). These direct the motion flow of the fluid in the domain. They are also defined as the face zone

in CFD.


There has been significant use of the boundary conditions in the research. The boundary conditions in the

research work consist of the inlet, outlet, similar symmetries, the model car with or without the spoilers and

tyres.

Inlet & Outlet Boundary:

The inlet & outlet boundary is the condition which serves as the input and output or inlet & outlet of the fluid

flow in the domain. They can be of different types, such as:

For incompressible flows: Velocity inlet and outflow.

General: Pressure inlet and outlet.

For compressible flow: Mass inlet and outlet

Special cases: Inlet and outlet vent.

Most of the time, the selection of the inlet and outlet depends on the type of geometry.

Application in the research methodology:

Since the geometric model is the car and the study needs to find the significant resistive drag forces, the

incompressible flow; input and output boundary condition is applied. This means that the model has an

velocity input and output resembling similar to the wind tunnel.

The other boundary conditions that have been used are the model car. The car surface is the region of

study for the effects of drag forces, down forces, pressure difference. Tyres have also been defined as a

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boundary. The reason for using tyres separate from the car model is to study the similar forces affecting

the tyres (fig 43).

3.3.7 COMPUTING SETUP

Parallel computing for processing has been used in the processing set up for the models. The reason of

using parallel computing is because; single processing allows solving one discrete problem at one time.

Parallel processing is used to make more than one processing at a time. This is time efficient while double

precision is used to change the magnitude order of the residuals (explained in chapter 4, 4.10).

Figure 43 defining the boundary conditions on geometry in ANSYS

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3.3.8 CONVERGENCE

Convergence is the way of obtaining accuracy. All the models in the research work have been

converged before they are proceeded to post processing analysis. Convergence is the way of obtaining

accuracy for the model. Number of iterations is made to run to check the convergence of the governing

equations. This is usually estimated by the RMS value depending on the precision of the processor (either

single or double). RMS value usually varies between 106 to 10

12. Once the convergence is achieved, the

results can be more precise.

Application in the research work:

Every model before post processing in the ANSYS Fluent is checked for convergence. This is obtained by the

successfully running the iterations along with the equations. The solutions once converged (fig 44) results in

better accuracy of the results.

Figure 44 obtaining convergence of the operating equations in ANSYS Fluent before post processing

3.3.9 ERRORS

Physical Errors:

Errors that are generated due to the uncertainty in the formulation of the models are called physical errors.

They can be mainly due to mathematical rounding off, initial conditions, and mathematical assumptions or

form

57

Discretization Error:

They occur often from the governing flow equations. Discretization errors can be defined as the difference

between the perfect solution to the discrete equations and analytical solutions to PDE. They can be classified

as:

1. Spatial and temporary discretization of the flow

2. Truncation Error: This error can be defined as the difference between the partial differential equation

and the finite equation.

Programming Errors:

Generally happens due to bugs or referred as mistakes in the programming.

Computer-round off Errors:

These errors can cause inaccuracy or may prevent convergence. Usually when the exact solution could not be

extracted from the discrete equations, they are rounded off as finding the determining the difference between

the two discrete points can consumed huge memory.

Iterative Convergence Error:

This usually happens when slow computing power and time consuming iterations are generally truncated to

the final solutions which lead to the numerical error in the solution called the iterative convergence error.

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CHAPTER 4

NUMERICAL SETUP

Figure 45 Top and bottom shows analysis of the

models in the ANSYS

59

4.1 INTRODUCTION

The designs were constructed as models in Autodesk Inventor 2014 and exported as .iges extension

format so that the file could be easily simulated on the ANSYS CFD for analysis. The analysis of the CFD is

the results, refined after continuous changes of different spoilers to find the values of coefficients of drag and

lift shown in the next chapter.

The survey is collaborative effort of the research of the designs available in the market from variety of

the websites and articles in magazines. Collectively three designs were selected after the survey. Before

proceeding to the next subtitles and topic there are certain parameters and pre requisite knowledge required.

Pre-requisites

Autodesk Inventor – 2014: The researcher has used Inventor professional 2014 ‘student edition’ for the

purpose of designing the spoilers. Hence it is important to know how to use inventor 2014. Alternatively other

software’s could be used. The final design has to be exported in either of the extension formats of

.iges/.igs/.stp/.step to be able to read the file on ANSYS CFD.

Limitation: Since the car base line model generated is 2 dimensional (dependent on subtopic 1.5) the models

of spoilers are also in 2 dimensional surfaces.

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4.2 DEVELOPING THE DIGITAL BASE LINE MODEL

4.2.1 GEOMETRY

The concepts developed through the project needs to be applicable on the popular sedan classes and

should be beneficial for an average buyer. As discussed earlier most of the modern day cars experience the

aerodynamic forces. A generic car profile that represents the aerodynamic characteristics and geometry of the

cars in the notchback class is constructed and used as the base line model (BLM) for the research. Even

different car manufacturers have variety in design, geometry and features but substantially do not differ a lot

and have similar aerodynamic characteristics. According to Hucho (Dimitriadis, 2014) the general dimensions

of the car such as the frontal area, length, width and height of the cars do not vary significantly between

manufacturers. However they are optimised moderately to limits by most of the designers. This results is

similar properties, geometry and drag coefficients between the makes. This similarity between the

manufacturers means that the vehicle from one manufacturer closely represents the same aerodynamic

properties of the same class form most manufacturers.

The BLM used for the construction and analysis in the research is BMW 316i ES Saloon, a BMW automobile

car. The model has been chosen because of its god availability of the information. The proportions and

geometry of the BLM has also been extracted to a non-scale model in CAD file to ensure the accurate

aerodynamic simulation of vehicles in the class.

The aim and objective is to generate a CAD file of the BLM notchback which represents the similar properties

of the same class of manufacturers. The BLM is made up in 2 dimensional surface models as dependency and

project limitation of the computer specifications. According to the Katz (Katz, 2006), the average coefficient

of drag among the cars in the notchback class differs from 0.3 to 0.4 with an average frontal area ranging from

1.4m2 to 2.2m

2. It is not the aim to generate the BLM based entirely on the BMW 3 Series sedan mode ;

however the model needs to be a representative of vehicles in the same class.

Finally the methodology is followed by ANSYS CFD observations and calculations.

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4.3 MODELING IN THE INVENTOR 2014

As mentioned there is variety of CAD software available in the market. For the ease of alterations and

modification it is recommended to use the CAE tool available with the FEA software. As an ease of use the

researcher has used Inventor Professional 2014. The designs of the BLM with and without the spoilers are

created as a 2 dimensional surface profile.

4.4 DESIGNING THE BLM

Original Specifications:

BMW 316i ES Saloon is a sedan class notchback series car. The specification of the car is mentioned

below (BMW UK, 2015). Since the design is two dimensional, the width can be ignored.

BMW 3 16i E Series

Specifications mm

Length 4,624

Height 1,429

Figure Courtesy: BMW UK, website

Using the original specifications, the BLM is designed in the Autodesk Inventor Professional 2014. One of the

features of the software is to generate the model of the actual type in compressing the size ratio. The steps of

design have been explained below.

Figure 46 BMW 3 series dimensions

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Inventor Steps:

Step 1: Initial Setup

Open the software. Since this is our first design of the BLM select “new” and consecutively confirm the

measurements in “standard – mm” for the metrics as shown in the figure 47.

Figure 47 Initial steps using inventor

Step 2: Selecting the design sketch

Once the workspace opens, select the type of sketch that needs to be drawn. This is done by selecting the

create sketch option and selecting “2D Sketch”.

Figure 48 generating a 2D sketch

on inventor

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Step 3: Selecting the work plane

Once the 2D sketch is selected, generate the XY plane from the origin, displayed on the left panel. This

automatically confirms the XY plane (front) to draw the sketch.

The design of the car has been simplified by importing the picture of the car from the website (BMW UK,

2015). Measuring the size of the car in the picture and comparing the actual size will ease the ratio of model

to original prototype.

Step 4: Importing Image based design

Click on the image option on the tool bar and option for insert image has been selected. The image is imported

into the plane where the sketch is drawn (Autodesk Inventor Professional, 2014)

Figure 49 creating a sketch

Figure 50 using image pointing system to generate BMW 3 series model

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Step 5: Designing using points

Using the point based way to design; points are clicked on the outer boundary of the car. This means the

point’s line on the surface of the car in the picture. The reason to use the image pointing system is to connect

the points at the end to generate the model car and then delete the picture.

Figure 51 importing the image

Step 6: Finalising the sketch and dimensioning

The dimension of the picture is calculated and the ratio of the actual to the model is derived. In the research

model the scaling of the model to the actual car is 1:28 length and height.

Figure 52 creating the constrained sketch

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Step 7: Creating the boundary walls

The next step is to create a surface boundary that will be needed for the CFD analysis. This will feature the

boundaries like the inlet and outlet wall. The selection of the boundary is based on the length of the model.

The rear of the model has a length of 5’x’. This means five times the length of the model while the height

thrice of the length.2 The front of the model is at a distance of same length of the model.

Figure 53 creating the boundary walls for ANSYS

Step 8: Generating the Boundary surface

After the boundary layer is created, the final step is to create the boundary patch. This is to make the boundary

separate from the model sketch. In ANSYS the boundary patch acts as the region of fluid flow. Select the

option of boundary patch from the tool bar. Select the region without the sketch of the model to be confirmed

as boundary patch. Finish by confirming.

The selected region highlights with grey effect on the sketch.

2 The length and height of the boundary has been considered 5x and 3x where x is the length of the model. The reason for

selecting the boundary with the variable multiple lengths and height is the reason that the boundary should be well far of

the car. The existence of car should have no effect on the boundary.

66

Figure 54 creating the boundary patch for boundary walls

Figure 55 finishing the boundary patch

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4.4.1. BLM PRESENTATION

68

4.5 MODEL WITH BUILT-IN SPOILER BY MANUFACTURER

69

4.6 MODEL WITH DECKLID SPOILER

70

Most commonly used spoiler in automobile industry is the deck lid spoiler. There are two types of deck lid

spoilers. Spoilers that are added on the trunk of the car separately and the other type of deck lid spoilers with

elevation on the rear end of the trunk.

Figure 56 Deck-lid model spoiler

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4.7 MODEL WITH OPEN TYPE SPOILER

72

4.8 ANSYS WORKBENCH SETUP

The model in the CAD format needs to be exported to the ANSYS Workbench. Since the model deals

with the research of the fluid flow, the analysis system that needs to be used is the ANSYS Fluent.

Procedure:

Run the ANSYS Workbench 15

Select the Analysis tool as Fluid Flow FLUENT CFD from the left tool selection bar.

On the workspace in the right hand side CFD opens up.

Simultaneously multiple models for analysis can be used to run and extract the results on one

workbench.

Figure 57 ANSYS workbench

Step 1: Extracting the CAD file

The CAD file is imported to Workbench. In the ANSYS setup for the research work, four models of the BMW

3 E 16 series car (three with manufacturer’s spoiler, deck lid spoiler and open spoiler along with the BLM) are

imported to 4 work space (fig 57).

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Step 2: Updating the boundary condition for the FLUENT

As explained in the topic 3.7 of chapter 3, every model needs to have assigned the boundary conditions. The

inlet as mentioned will be the velocity inlet since we assume the car is in motion. The models depending on

whether BLM or spoiler models are defined as the car body.

Select the edge selection from the top tool bar as shown in figure. This allows selecting the edges and

naming them. Manually feed the names. As for this research work all the four models have left wall as

Inlet, right wall as outlet, top and bottom wall as symmetries, model without the tyres as car body and

tyres separately as tyres in named selection. This is to ease the post processing and finding the result

as well as identifying the boundaries during post processing.

BLM Geometry setting :

Figure 58 generating the named boundaries

74

Manufacturer’s model with built-in spoiler (Geometry settings)

Figure 59 generating the named boundary and geometry condition in built-in the model

75

Similarly for Deck-lid and Open spoiler models

Figure 60 generating the boundaries for Open Spoiler model

Figure 61 generating boundary conditions for deck-lid spoiler model

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Step 3: Setting the Meshing

Topic 3.5 in chapter 3 describes two types of meshing. ANSYS Fluent automatically uses unstructured

meshing. In the models the automated meshes needs to be adjusted3.

Select the option of mesh from the left hand tool box

Select the option of sizing from the bottom menu.

From the sizing, change the minimum size of the mesh from automatic to manually fed value in mm.

Update the project to observe the change.

BLM Meshing

3 All the adjustments for the meshing in the models have been defined.

Standard 1 mm for the minimum size and 2 mm for the maximum size

of the mesh elements have been taken in considerations.

Figure 62 default mesh

Figure 63 adjusting the mesh to 1 mm minimum and 2 mm maximum

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BLM updated mesh

Similarly the other models are updated top fine mesh.

Manufacturers’ built in spoiler model mesh

Figure 64 Updated mesh of BLM

Figure 65 updated mesh of built-in model spoiler

78

Deck lid Spoiler model

Open Spoiler model with updated mesh

Figure 66 updated mesh of deck-lid spoiler

Figure 67 updated mesh for open spoiler

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Step 4: FLUENT Setup

After all the alterations and adjustments are done in the meshing, the set up needs to be checked and modified

before running the solutions.

This is done by the following ways (figure 68)

Select the setup option from the work space.

Select 2D for dimension

Use Double Precision for options.

For processing options select the parallel (refer Chapter 3) & use the value 4

Figure 68 Fluent setup

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4.9 POST PROCESSING SET UP

The analysis on the fluent is obtained with modifications and moderations in the processing setup.

This includes the selection of density of the fluid, assigning a fluid inlet speed, checking the convergence of

the model. All the models are followed with the steps below before analysing the results.

General Settings:

Two-equation turbulence models are very widely used, as they offer a good compromise between numerical

effort and computational accuracy. In two equation system, both the velocity and length scale are solved using

separate transport equations (hence the term ‘two-equation’). The k- Ɛ and k-ω are which are the two-

equation models use the gradient diffusion hypothesis to relate the Reynolds stresses to the mean velocity

gradients and the turbulent viscosity. The turbulent viscosity is modelled as the product of a turbulent velocity

and turbulent length scale. The solutions from the transport equation provide the turbulent velocity scale

computed from turbulent kinetic energy of the two equation model. There are other models which uses more

than two equation model example Transition SST (4 –Equations), LES, Reynold’s stress (7 equations). They

tend to have more accuracy but are more time consuming processing.

General Solver:

In the research work we will use, pressure based solver type. The reason for using pressure base

solver is: The pressure-based and density-based approaches differ in the way that the continuity, momentum,

and (where appropriate) energy and species equations are solved. Pressure-based solver traditionally has been

used for incompressible and mildly compressible flows. The density-based approach, on the other hand, was

originally designed for high-speed compressible flows (shown in fig 69).

Figure 69 applying the general settings

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Choosing absolute or relative velocity formulation

It is used to result most of the flow domain having velocities in that frame. Hence forth It reduces the

numerical diffusion in the solution and generate more accuracy.

Usually absolute velocity formation is used for the applications where the flow in the domain is not

rapidly rotating for example a large room.

Application in research

Since the boundary condition is quiet large in the research model, we will use absolute velocity

formulation.

However the relative velocity formulation is used where the fluid domain is rapidly rotating for

example a mixer tank.

Energy Equation: It is used where there is a variance of the temperature effect in the fluent analysis.

Since the research model focuses just on reducing the lift and drag forces, we can ignore the energy

equation.

Using Steady time: It refers to flow being steady with the variance of time and takes lesser time to

converge.

Figure 70 changing the velocity formulation

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Figure 72 adjusting the fluid selection

1. Model calculation Selection:

Set the fluid selection as air with constant density with K- omega of 2eqn from viscous laminar shown below.

Figure 71 adjusting the model settings

2. Fluid Value setup

Select the fluid that will be used to analyse the model as air with constant density of 1.225 kg/m3. The reason

for selecting the constant density of the fluid is explained in chapter 3. [] figure []

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3. Assigning values to the named boundary

It is important to assign values to the boundaries generated. The inlet wall needs to be velocity inlet, outlet

wall to be pressure outlet. All the models have been assigned a value of 60Km/hr i.e 16m/s of velocity inlet.

4. Running the solution initiation

This allows checking the model for any possible errors. Select the solution initialization and select Hybrid

Initialization as shown in figure

Figure 74 selecting the initialization

Figure 73 assigning the input velocity (similar for all 4 cases)

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Difference between hybrid initialization & Standard initialization

Hybrid Initialization: It is a method of initialization in ANSYS Fluent. Hybrid initialization uses a mixture

of different interpolation methods. Using Laplace equation it solves the velocity and the pressure fields. Other

variables like the temperature, turbulence, specific fractions will be patched automatically depending on the

interpolation and domain averaged value.

Standard Initialization: This is the method of initialization in ANSYS Fluent by manually assigning the

variable and value. This can be used to monitor small changes and assign difference in pressure, velocity or

turbulent kinetic energy.

5. Running Calculations:

This feature enables to run assigned number of iterations. It is useful to find the convergence (explained in

chapter 3 [] ) of the equations being used in the CFD. Once the solution is converged, the accuracy of the

result increases. All the models have been assigned for 1000 iterations.

Figure 75 selecting number of iterations for accuracy

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Figure 76 shows converging the equations

Figure 77 showing the converged equations

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4.10 RESIDUALS & ERRORS

Residuals:

When solver iterations are calculated, the residual sum of each conserved variable is computed and

stored. This helps in recording the convergence history. In ideal process with infinite precision the residuals

tend to be zero when the convergence occurs. However the scenario in actual computing is different. The

residuals tend to be small valued and then stop changing. Their magnitude differs with single precision to

double precision ranging from six to twelve orders of magnitude respectively before rounding off.

Errors:

2D geometry analysis on Fluent has certain errors on the pressure and the velocity contours. Since the

geometry defines a boundary layer, it assumes that the region in the front is closed with the tyres and the

bottom symmetry.

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CHAPTER 5

ANSYS FLUENT RESULTS & ANALYSIS

88

5.1 INTRODUCTION

Every model is run on the ANSYS Fluent to obtain a simulated picture which shows different

physical properties that affect the model. The coloured picture depicts the values of the physical properties at

the instant. This half of the chapter is to analyse the models with the results obtained in the pictorial form and

find the coherence with the graphs and physical theories.

5.2 ANALYSIS FOR BLM

Velocity Contours:

The velocity magnitude is the instantaneous speed of the model car. The region of light brownish yellow

colour shows the normal velocity of the fluid (air) in the domain. As the model car travels with 16 m/s the

velocity of the air changes with the position of the car. In the figure 78, the air has velocity of 15 m/s. As the

air along the car model is brought closer towards the bonnet, the velocity rise from 20 m/s of the orange patch.

It keeps increasing to 24.20 m/s on the top roof surface of the car in pale red patchy region and drops slowly

on the top surface about a distance of almost twice the length of the model.

On the bottom part of the model car, the velocity of the air exhibits very low or negative value of no air

movement. This is shown as region of ocean blue colour having velocity of 4m/s to -3.79 m/s. This is one

limitation in 2D model. In real case, the model will have fluid velocity on the bottom surface too thus having a

value greater than zero. The error is explained in chapter 3, topic errors.

Figure 78 Velocity magnitude picture from Fluent

89

Pressure Contours:

Figure 79 pressure contours

Figure 80 shows static pressure graph

90

Static pressure:

From the image it can be observed that the static pressure on the body of the model car fluctuates a lot on its

boundaries. The front region of the car exhibits an extensive pressure. The region for the high pressure is

explained in the topic of errors and residuals in Chapter 4, topic 4.10.

Region of stagnation:

The stagnation point can be seen in the front of the car figure 81, which has ‘V’ shaped cut from the body

panel to the bumpers. This is the region which comes in contact to the air at first instance when the car is in

motion. The model shows a pressure of 250 Pa.

Relation of the image along with the graph

As the design is further analysed the static pressure fluctuates from 210- 200 Pa. to around 105 Pa. at the

lower surface of the model car. Similarly for the top surface of the car the pressure varies from the 5 Pa. at the

top bonnet drops, increases to air pressure taken as standard 0 Pa, again drops to about -225 Pa.

Turbulence Contours:

Stagnation point

Figure 81 shows the stagnation point

Figure 82 shows turbulence graph of the BMW Body and the tyres (in red)

91

5.3 ANALYSIS FOR MANUFACTURER MODEL

Velocity Contours:

As explained in the model car without any spoiler, the figure 84 below shows the velocity magnitude of the

model with built-in spoiler. The magnitude of velocity of the air as it hits the car bonnet top surface starts to

increase from 16.40 m/s and reaches at a maximum of 24 m/s or greater on the surface of the bonnet. Similar

phenomenon happens at the top surface of the model car roof. Further moving with the top geometry of the

model car to the rear part the velocity approaches to 0. Both the figures 84 & even in the x direction figure 84

the velocity of the air reaches to 0. This is a case of error and residuals explained in chapter 3, topic 3.3.9

Magnitude:

Figure 84 Velocity magnitude in manufacturer’s –built in model

Figure 83 Velocity in X axis

92

Figure 85 shows velocity in Y direction

The figure 85 above shows the velocity of the air in Y direction. The frontal region shows a high velocity of

air reaching up to 19.20 m/s from 7.3 m/s in the regions of the change in geometry. Since the flow of air is in

x direction, there is more contribution of the velocity contours toward the x axis opposite to the motion of the

model.

Pressure Contours:

The region of the static pressure across the manufacturer model remains similar with high concentration of the

pressure around the frontal types. The point of stagnation does not change. However the region of the pressure

across the body has minute changes from the frontal to the rear geometry.

Figure 86 shows the pressure contours

93

Comparing the picture with the graph:

The lower graph with the position depicts the top surface of the model car with manufacturer’s built-in

spoiler. The graph of the static pressure increases from a negative -155 Pa. approx. pressure (shown in slight

ocean blue colour region) to the normal environment pressure of 1 Pa. shown in greenish effect colour.

Further moving along the geometry to the top surface the pressure drops exactly where the dash broad screen

and the roof meet dropping to -245 Pa. (in royal blue colour). With the further observation moving towards

positive x direction the pressure starts to increase and come to normal air pressure.

The same happens to the bottom surface shown in the upper graph. The value of pressure increase to

approximately 201 Pa. maximum and further beyond the front tyres it starts to fall to the normal air pressure

till it reaches the rear of the car model.

Figure 87 shows the static pressure graph

Figure 88 shows same stagnation region as the base line model

94

Error in model CFD:

The pressure starts to increase and keeps on increasing to approximately 201 Pa. This seems to show that the

velocity of air is very less or negligible. This is an example of error in 2D geometry. Since in 2D geometry,

the computer assumes the boundary to be closed and no possibility of the air movement. However in reality is

a different case. The air passes underneath the car trunk. Thus the pressure should not be that high which can

make the model car lose control.


As discussed in chapter 2 of general concept and theories, turbulence generated by the built-in model of the

car is different than the generic BLM. The turbulence at the rear of the built-in spoiler model makes a ‘V’

shape. The region of higher turbulence is present almost thrice the distance of the rear of the model.

Comparing the model picture with the graph:

The region of the higher turbulence can be observed around the region of higher chaotic properties. The

turbulence reaches to a significant 26.20 m2/s

2 from normal of 0. And slowly diffuses back.

Figure 89 shows the turbulence in case 2

95

The region of high turbulence is shown by the red dotted line in the picture.

Reason of the V shaped push and higher turbulence.

Since the built-in model of car has a spoiler with steep divergence on the top, it diverts the air from the rear

trunk of the car. This indirectly diverts the flow. Once the flow is diverted and it joins again the top velocity,

causing different flow mixtures. Once the velocity of the air flow reduces, it introduces low momentum

diffusion, high momentum convection & rapid variation of pressure and flow at that instant of time and

distance generating higher turbulence.

Figure 90 shows the kinetic energy of the turbulence region

96

5.4 ANALYSIS FOR DECK LID SPOILER

Velocity Contours:

The magnitude of the velocity increases from 16 m/s to 24.60 m/s (Yellow to red region figure 91) as it hits

the bonnet of the car. Thus it reduces the pressure which can be visible when we compare the static pressure

pictures and data. The velocity contours keep on increasing as we move further on the top surface towards

positive Y direction. As the air strikes the top surface it increases the velocity and then to move in a parabolic

path till it reduces.

However there is a reduced velocity magnitude at the bottom surface of the car and at the rear part. The

velocity reduces to 1.23 m/s and has a curved line shaped at the rear in royal blue colour. There is mixture of

different velocity magnitudes at the rear ranging from 16m/s to 4.91 m/s

Figure 91 shows velocity magnitude in deck-lid spoiler

Figure 92 shows velocity in x direction

97

However the velocity in the x direction shows least circulation around the spoiler region. And variation of the

velocity magnitude figure shows velocity changes of patchy region ranging 2.46 m/s to or below 4.91 m/s

Pressure Contours:

The pressure distribution for the deck-lid model of the car is quite different when compared to the previous

two models. The region of high pressure is the frontal part of the car. The pressure rises to a stagnation value

of 280 Pa. in the frontal part.

As we move along the geometry of the car, since the velocity increase, the pressure decreases at the bonnet of

the car. This can be established by the Bernoulli’s equation [] where velocity increase, the pressure reduces.

Patchy region within the box which

shows variation in the velocity

magnitude of the air near the spoiler.

Figure 93 enlarged picture showing the lesser velocity

around the model

Figure 94 showing the pressure contours for deck-lid model

98

Again comparing the picture 94 and the graph 95 shows the similar fluctuation in the pressure. The top of

surface of the model shows negative distribution of the pressure over the bonnet and increases to the normal

pressure. Further moving over the top surface the dark blue patchy region shows the drop in the pressure to

almost -240 Pa. approx...


The turbulent contours shown in the picture is different than the other two previous models. The region of

turbulence is wide spread showing a ovular patchy region with core of red region of 19.50 m2/s

2 and gradually

decreasing to 9.77 m2/s

2 and finally into the blue region of value to 0. This time the region of turbulence is

further away from the vehicle almost more than double the model length.

Figure 95 showing the static pressure region in graph

Figure 96 shows turbulence in the deck-lid spoiler car

99

5.5 ANALYSIS FOR OPEN STYLE SPOILER

Velocity Contours:

The velocity magnitude for open style spoiler also varies with the BLM and other two models. The velocity

magnitude also varies as with the other model along with the geometry. The velocity around the bonnet

increases up to 23.20 m/s falls little around the start of the dash board and again increases.

The region around the spoiler shows a velocity magnitude of between 2.44 m/s. The region behind the rear of

the car shows a drop in the velocity. Slowly the velocity magnitude increases too an resumes to the 16 m/s

Figure 97 shows the velocity contours for open style spoiler model car

Figure 98 shows the velocity in x direction

100

Error:

The region around the front end of the model, the rear end as well as the base shows very little movement of

the air. This is the limitation of using 2D model. The computer assumes that the regions are fixed and closed.

However in the realistic model or 3D analysis, there exists velocity underneath the car.

Pressure Contours:

The pressure distribution across the geometry of the open spoiler model is again different to that of the others.

However the region of stagnation remains the same. Pressure decreases at the top surface of the bonnet where

the velocity is high and on the start of the roof top. The pressures around two regions are approx... -213 Pa.

Error:

The region of stagnation is similar to the region of least velocity (using Bernoulli’s equation). This is because

of the geometrical limitation of the 2D model which assumes the boundary to closed and definite underneath

the car. The region has a very high pressure value of 207 Pa making it unrealistic figure 100. The same reason

follows for the underneath of the model car which shows value around 141 Pa.

Unrealistic region around the tyres

showing very less or no velocity

magnitude.

Figure 99 shows enlarged image of the velocity magnitude

Figure 100 shows the pressure contours in open style spoiler model

101

Comparison of the picture with the graph:

The graph shows exactly what the figure depicts in contours. The lower graph shows the top surface of the car

while the top graph shows the lower surface. As we analyse the pressure values from the region of low

pressure it increases up to a normal standard air pressure value and again drops around the roof and slowly

regains.

The region around the spoiler has a pressure value ranging in between -40 Pa.


The region of turbulence is quiet near to car rear. It shows an unfavourable or chaotic region of velocity,

regaining the momentum. The region of high turbulence can be seen in patchy red and slowly regaining to

normalcy.

Figure 101 shows the graph for the static pressure along with the geometry

Figure 102 shows the turbulence contours for the open style spoiler model

102

5.6 VELOCITY MAGNITUDE COMPARISION TABLE:

Figure 103 shows the velocity magnitude. From top to bottom Case 1, 2, 3, 4 respectively

103

Table 1 Upper body velocity magnitude for case 1, 2, 3, 4

Comparison Table:

Table 2 Lower body velocity magnitude for cases 1, 2, 3, 4

Model

Upper Front

Velocity magnitude

in m/s

Upper Rear Velocity

magnitude in m/s Upper region of high velocity magnitude

BLM –

Normal car 16 – 24

Gradually decreases from

24- 20 and then to 16

Red Patchy areas on the surface of the car

bonnet, top surface where geometry changes

i.e. dashboard meets the roof.

Built-in

spoiler

model

16 – 24 Decreases from 23 to 20

and finally to 16

Shown in the dark red coloured region on the

bonnet and starting of the roof surface.

Deck-lid

Spoiler

model

16 – 24

Decreases leaving a large

area on the top of about a

value 22

Bonnet of the car and almost more than

twice the distance of the car on the top

surface.

Open

Spoiler

model

16 – 24 Follows a gradual

decrease from 23 - 16 Same region as of the BLM model.

Model Lower front velocity

magnitude in m/s

Lower rear velocity

magnitude in m/s

Lower region of low velocity

magnitude

BLM –

Normal car 6.01 – 1.81

Gradually decreases from

4.61to negative 2.39

The region is showed by the patchy blue

colour changing from light blue to dark

blue colour.

Built-in

spoiler

model

3.82 - 0 Gradually decreases from

9.81 to a value of 0

Shown in the light regions to the dark

effect.

Deck-lid

Spoiler

model

2.66 - 0 Decreases from a value

of 2.46 to a value of zero.

The entire lower region shows a very low

velocity magnitude from 4.91 to zero in

blue regions.

Open Spoiler

model 4.89 - 0 Decreases from 1.22 to 0 Same region as of the BLM model.

104

5.7 PRESSURE COMPARISION:

Figure 104 shows the pressure contours for

cases 1, 2, 3, 4 respectively

105

Pressure Graphs:

Figure 105 shows the pressure graphs for cases 1, 2, 3, 4 respectively

106

Table 3: Upper body pressure comparison for cases 1, 2, 3, 4

Table 4: Lower body pressure comparison for cases 1, 2, 3, 4

Model Upper front pressure in

Pascal

Upper rear pressure in

Pascal

Discussion of upper region of

pressure

BLM –

Normal car

Region of low pressure is

visible of about 0 – 5

Shows a very low pressure

on the top roof surface of

the model

The top surface shows a variation of

the pressure from low to the normal

air pressure.

Built-in

spoiler model

Region of the low

pressure is visible similar

to the BLM model

Shows the region of the

distributed low pressure

around the spoiler about -

85

The top region shows a greater area

of the low pressure since the

velocity magnitude is very high

Deck-lid

Spoiler model

Region of low pressure

starts at the same region

as shown in the BLM

Top surface has the

minimum pressure

The pressure around the upper

region stays at the same pressure of

-92.50 around the spoiler

Open Spoiler

model

The region has less low

pressure compared to the

other models.

The roof of the car has the

lowest pressure varying

from -235

There is a patch of low pressure of

about 102 over the spoiler.

Model Lower front pressure

in Pascal

Lower rear pressure in

Pascal

Discussion of lower region of

pressure

BLM –

Normal car

Region in the front of

the car shows a

stagnation of 205

The lower rear region

shows the pressure

varying about a value of -

102

The region underneath the trunk of

the car is an unrealistic image

showing high pressure

distribution.

Built-in

spoiler model

The region of high

pressure is similar to the

BLM

The lower rear pressure is

low with similar to the

upper rear part.

The pressure underneath the trunk

lies between 35

Deck-lid

Spoiler

model

The region of front part

exhibits the same high

stagnation point.

The pressure in the rear

part is similar to the BLM

model.

The pressure underneath the trunk

of the car is around -31.17 which

unrealistic.

Open Spoiler

model

The stagnation point is

same.

The rear lower part has

the same values of

pressure as the upper rear

part with few difference.

The pressure under the trunk is

about 119 which is again not

idealistic due to 2D geometry

limitation and error.

107

5.8 TURBULENCE COMPARISION

Figure 106 shows the turbulence regions in cases 1, 2, 3, 4 respectively

108

Comparison table:

Table 5: Comparison table for turbulence in cases 1, 2, 3, 4

Wake Turbulence:

Usually wake turbulence is formed behind the aircraft as it passes through the air. Similarly wake turbulence

is formed behind the air foils of the cars. But these are so less that it can be considered no effect on the other

automobiles on the road.

Model Turbulence region/

value Description

BLM –

Normal car

The region of turbulence

is way behind the car.

The turbulence does not have or matches with the streamline flow.

The wake region is quiet near to the car rear field.

Built-in

spoiler model

The region of the

turbulence is not very far

from the model.

The wake region and the area of the recirculation lies very close

approximately twice the distance of the car.

Deck-lid

Spoiler model

The turbulent region is

quiet widespread almost

very far

The turbulent region shows a stream line recirculation. The wake

is widespread but obviously stream lined.

Open Spoiler

model

The region has the similar

effect as that of the Deck-

lid Spoiler.

The turbulent region follows the similar streamline flow. The

wake field is quiet far from the model car and hence would have

negligible effect on it.

Figure 107 shows region of wake turbulence

109

5.9 RESULTANT FORCES

Table 6: Resultant forces on the model car body for cases 1, 2, 3, 4

Representation is done in (x, y, z) coordinate system.

Table 7: Resultant forces from tyres for cases 1, 2, 3, 4

Model Pressure Forces (Net) N Viscous Forces (Net) N Total Forces (N)

BLM – Normal

car (-1.0449, 31.3209, 0) (0.1317, 0.04291, 0) (-0.8832, 31.3685,0)

Built-in spoiler

model (-1.007358, 22.5983,0) (0.15941, 0.04293, 0) (-0.847946, 22.64123, 0)

Deck-lid Spoiler

model (-1.114174, 23.351746, 0) (0.1559896, 0.03976, 0) (-0.95818, 23.39153, 0)

Open Spoiler

model (-1.1551695, 31.0380, 0) (0.1558332, 0.0416366, 0) (-0.99683402, 31.0796, 0)

Model tyres Pressure Forces (Net) N Viscous Forces (Net) N Total Forces (N)

BLM – Normal

car (5.710411, 0.24515, 0) (0.020252245, -0.00025567, 0) (5.7306627, 0.24489, 0)

Built-in spoiler

model (5.5206733, 0.30913989, 0) (0.016064, -0.0005722, 0) (5.536738, 0.3085676, 0)

Deck-lid Spoiler

model (5.56199, 0.075365, 0) (0.017534, -0.00045973, 0) (5.579523, 0.074950, 0)

Open Spoiler

model (5.741489, 0.2409329, 0) (0.02036237, 0.000258597,0) (5.761852, 0.2406744, 0)

110

Total drag and lift forces:

Table 8: Total drag and lift forces in cases 1, 2, 3, 4

Comment from the table:

From the above comparison of the total drag forces and the total lift we can say that all the three models have

contributed somehow to reduce the drag and lift. However spoiler which is closed with the rear trunk has been

beneficial in reducing the drag and the lift up to 10 N from the actual model without any spoiler.

Model tyres Total Drag Forces (N) Total Lift Forces (N)

BLM – Normal car 4.8474577 31.608742

Built-in spoiler model 4.6887922 22.949804

Deck-lid Spoiler model 4.6213429 23.466435

Open Spoiler model 4.7650178 31.320337

111

CHAPTER 6

CONCLUSION & FUTURE SCOPE

Figure 108 figure of a deck-lid spoiler at rear of BMW 3 series.

Picture courtesy: BMW website

112

Conclusions

Different types of cars in sedan class use rear trunk spoilers. The research focused on the application

of the rear spoiler designed in 2D and explained in CFD processing tools which address the problem

statement by allowing the model car ‘BMW 3 series’ to withdraw its drag and reducing the lift. This

has the effect of streamlining the model car to attain the lowest possible drag and lift when required in

high velocity.

The system was successfully simulated and compared against the performance of the BLM and other

three models. The CFD simulation allowed a direct comparison of the three different types of spoiler

along with the car model. This comparison also helped in comparing the post process values obtained

from ANSYS Fluent. The first set up was to analyse the background and possible scope of the product

in the automobile industry.

The research focused generalising the basic concepts of the governing laws and theories of the fluid

flow around the spoilers. This helped in establishing the concept with the product. Apart giving a

broad introspect to the concepts, this was followed by the research methodology which dealt with the

basic approach of the research work. Being quantitative in nature and mixture of qualitative

techniques resulted in the scope of understanding the different ways of approaching the problem

statement.

Understanding prediction methods and reason of using the numerical method is well established by

the fact that, the problem statement needed a discretization technique to approach the solution. This

was a great leap by using the FVM (Finite Volume Method). Using the digital computing, the solution

could be achieved.

As the geometry is obtained, it is scaled to a smaller model. Using inventor, the design for the

different models was obtained. The pre-processing setup was used to analyse the standard tools used

in the fluent setup.

The research post processing chapter 5 – Fluent results and analysis shows the region of the high and

low velocities of air, turbulent region of the car models and pressure analysis across the geometry of

the models.

113

The resultant comparison of the drag forces and lift forces well establish that a normal car without the

rear spoiler has higher values than that of the drag and lift compared to the model with the spoilers.

Compared to other models, the built-in model provided the best results for the aerodynamic forces.

Future Scope

This research project is a general introduction towards the application of aerodynamic rear spoilers in the

Sedan class cars. Because of this a lot of possible future work can be conducted undertaking this project as a

base to initiate.

For instance in order to understand the application of aerodynamics in a two dimensional car surface,

simulations can be carried out with different model of spoilers ranging from built-in and open type can be

created. Mapping of the pressure distribution, velocity contours and turbulence behind the cars with ANSYS

CFD Fluent simulation can be a leap to map the aerodynamic forces. This is a very useful tool in obtaining the

information about the trends and behaviour of the complete car in motion. As mentioned in the result section;

simulated model of the BLM and the models with spoilers can generate results that can be dimensionally

analysed, however the accuracy of the result depends on the limitations and errors of the two dimensional

geometry.

On the other hand if the generic dimensions are used for the same simulation, the results could be applied to

any Sedan class cars exceeding 4.5 metres in length. Another important point would be confirming and

validating the conclusion of the rear spoiler not working properly as a result of multiple simplifications

applied to the future model. Finally due to the heavy unsteady behaviour of the vehicles around wake

turbulent region can be investigated including unsteady simulations which could be a future aspect or

compliment to tis research project(obviously in two dimensional Analysis) along with the wind tunnel test.

114

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http://www.exa.com/aerodynamic_efficiency.html

The Bizarre German Car That Was Ultra-Aerodynamic?And Totally Impractical | WIRED. (n.d.).

Retrieved from http://www.wired.com/2014/09/german-aerodynamic/

Design Real. (n.d.). Retrieved from http://design-real.com/spoiler/

Drag Queens: Aerodynamics Compared ? Comparison Test ? Car and Driver. (n.d.). Retrieved from

http://www.caranddriver.com/features/drag-queens-aerodynamics-compared-comparison-test

Spoiler Alert: A History of Downforce. (n.d.). Retrieved from http://jalopnik.com/5659723/spoiler-

alert-a-history-of-downforce

Wings/Spoilers: You're probably doing it wrong. (n.d.). Retrieved from

http://oppositelock.jalopnik.com/wings-spoilers-youre-probably-doing-it-wrong-1665312667

118

APPENDICES

APPENDIX 1

What Are the Navier-Stokes Equations?

The Navier-Stokes equations govern the motion of fluids and can be seen as Newton's second law of motion

for fluids. In the case of a compressible Newtonian fluid, this yields where u is the fluid velocity, p is the fluid

pressure, ρ is the fluid density, and μ is the fluid dynamic viscosity. The different terms correspond to the

inertial forces (1), pressure forces (2), viscous forces (3), and the external forces applied to the fluid (4). The

Navier-Stokes equations were derived by Navier, Poisson, Saint-Venant, and Stokes between 1827 and 1845.

These equations are always solved together with the continuity equation:

The Navier-Stokes equations represent the conservation of momentum, while the continuity equation

represents the conservation of mass.

How Do They Apply to Simulation and Modeling?

These equations are at the heart of fluid flow modeling. Solving them, for a particular set of boundary

conditions (such as inlets, outlets, and walls), predicts the fluid velocity and its pressure in a given geometry.

Because of their complexity, these equations only admit a limited number of analytical solutions. It is

relatively easy, for instance, to solve these equations for a flow between two parallel plates or for the flow in a

circular pipe. For more complex geometries, however, the equations need to be solved numerically.

Example: Laminar Flow Past a Backstep

In the following example, we numerically solve the Navier-Stokes equations (hereon also referred to as "NS

equations") and the mass conservation equation in a computational domain. These equations need to be solved

with a set of boundary conditions:

119

The fluid velocity is specified at the inlet and pressure prescribed at the outlet. A no-slip boundary condition

(i.e., the velocity is set to zero) is specified at the walls. The numerical solution of the steady-state NS (the

time-dependent derivative in (1) is set to zero) and continuity equations in the laminar regime and for constant

boundary conditions is as follows:

Velocity magnitude profile and streamlines.

Pressure field.

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/computational_domain.png

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/streamlines.png

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/pressure_field.png

120

Different Flavours of the Navier-Stokes Equations

Depending on the flow regime of interest, it is often possible to simplify these equations. In other cases,

additional equations may be required. In the field of fluid dynamics, the different flow regimes are categorized

using a non-dimensional number, such as the Reynolds number and the Mach number.

About the Reynolds and Mach Numbers

The Reynolds number, Re=ρUL/μ, corresponds to the ratio of inertial forces (1) to viscous forces (3). It

measures how turbulent the flow is. Low Reynolds number flows are laminar, while higher Reynolds number

flows are turbulent.

The Mach number, M=U/c, corresponds to the ratio of the fluid velocity, U, to the speed of sound in that

fluid, c. The Mach number measures the flow compressibility.

In the flow past a backstep example, Re = 100 and M = 0.001, which means that the flow is laminar and

nearly incompressible. For incompressible flows the continuity equation yields:

Because the divergence of the velocity is equal to zero, we can remove the term:

from the viscous force term in the NS equations in the case of incompressible flows.

In the following section, we examine some particular flow regimes.

Low Reynolds Number/Creeping Flow

When the Reynolds number is very small (Re≪1) , the inertial forces (1) are very small compared to the

viscous forces (3) and they can be neglected when solving the NS equations. To illustrate this flow regime, we

will look at pore-scale flow experiments conducted by Arturo Keller, Maria Auset, and Sanya

Sirivithayapakorn of the University of California, Santa Barbara.

121

About the Experiment

The domain of interest covers 640 μm by 320 μm. Water moves from right to left across the geometry. The

flow in the pores does not penetrate the solid part (gray area in the figure above). The inlet and outlet fluid

pressures are known. Since the channels are at most 0.1 millimeters in width and the maximum velocity is

lower than 10-4

m/s, the maximum Reynolds number is less than 0.01. Because there are no external forces

(gravity is neglected), the force term (4) is also equal to zero.

Therefore, the NS equations reduce to:

Modeling the Experiment

The below plot shows the resulting velocity contours and pressure field (height).

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/boundary_conditions.png

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/velocity_contours.jpg

122

The flow is driven by a higher pressure at the inlet than at the outlet. These results show the balance between

the pressure force (2) and the viscous forces (3) in the NS equations. Along the thinner channels, the impact of

viscous diffusion is larger, which leads to higher pressure drops.

Running such simulations using the NS equations is often beyond the computational power of most of today's

computers and supercomputers. Instead, we can use a Reynolds-Averaged Navier-Stokes (RANS) formulation

of the Navier-Stokes equations, which averages the velocity and pressure fields in time.

The Reynolds-Averaged Navier-Stokes (RANS) formulation is as follows:

Here, U and P are the time-averaged velocity and pressure, respectively. The term μT represents the turbulent

viscosity, i.e., the effects of the small-scale time-dependent velocity fluctuations that are not solved for by the

RANS equations.

The turbulent viscosity, μT, is evaluated using turbulence models. The most common one is the k-ε turbulence

model (one of many RANS turbulence models). This model is often used in industrial applications because it

is both robust and computationally inexpensive. It consists of solving two additional equations for the

transport of turbulent kinetic energy k and turbulent dissipation ϵ.

To illustrate this flow regime, let us look at the flow in a much larger geometry than the pore scale flow: a

typical ozone purification reactor. The reactor is about 40 meters long and looks like a maze with partial walls

or baffles that divide the space into room-sized compartments. Based on the inlet velocity and diameter, which

in this case correspond to 0.1 m/s and 0.4 meters respectively, the Reynolds number is 400,000. This model is

solved for the time-averaged velocity, U; pressure, P; turbulent kinetic energy, k; and turbulent dissipation, ϵ:

123

The results show the flow patterns, flow velocity, and turbulent viscosity μT.

Flow Compressibility

The flow compressibility is measured by the Mach number. All the previous examples are weakly

compressible, meaning that the Mach number is lower than 0.3.

Incompressible Flow

When the Mach number is very low, it is OK to assume that the flow is incompressible. This is often a good

approximation for liquids, which are much less compressible than gases. In that case, the density is assumed

to be constant and the continuity equation reduces to ∇⋅u=0. The creeping flow example showing water

flowing at a low speed through the porous media is a good example of incompressible flow.

Compressible Flow

In some cases, the flow velocity is large enough to introduce significant changes in the density and

temperature of the fluid. These changes can be neglected for M<0.3. For M>0.3, however, the coupling

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/flow_velocity.png

124

between the velocity, pressure, and temperature field becomes so strong that the NS and continuity equations

need to be solved together with the energy equation (the equation for heat transfer in fluids). The energy

equation predicts the temperature in the fluid, which is needed to compute its temperature-dependent material

properties.

Compressible flow can be laminar or turbulent. In the next example, we look at a high-speed turbulent gas

flow in a diffuser (a converging and diverging nozzle).

The diffuser is transonic in the sense that the flow at the inlet is subsonic, but due to the contraction and the

low outlet pressure, the flow accelerates and becomes sonic (M = 1) in the throat of the nozzle.

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/diffuser.png

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/mach_number.png

125

The results in these three plots show strong similarities, which confirm the strong coupling between the

velocity, pressure, and temperature fields. After a short region of supersonic flow (M > 1), a normal shock

wave brings the flow back to subsonic flow. This set-up has been studied in a number of experiments and

numerical simulations by M. Sajben et. al. [1-6].

What Flow Regimes Cannot Be Solved by the Navier-Stokes Equations?

The Navier-Stokes equations are only valid as long as the representative physical length scale of the system is

much larger than the mean free path of the molecules that make up the fluid. In that case, the fluid is referred

to as a continuum. The ratio of the mean free path, λ, and the representative length scale, L, is called the

Knudsen number, Kn=λ/L

The NS equations are valid for Kn<0.01. For 0.01<Kn<0.1, these equations can still be used, but they require

special boundary conditions. For Kn>0.1, they are not valid. At the ambient pressure of 1 atm – for instance,

the mean free path of air molecules – is 68 nanometers. The characteristic length of your model should

therefore be larger than 6.8 μm for the NS equations to be valid.

Finite Volume Method (FVM)

FVM is a discretization method for the approximation of a single or a system of partial differential

equations expressing the conservation, or balance, of one or more quantities. These partial

differential equations (PDEs) are often called conservation laws; they may be of different nature, e.g.

elliptic, parabolic or hyperbolic, and they are used as models in a wide number of fields, including

physics, biophysics, chemistry, image processing, finance, dynamic reliability. They describe the

http://www.scholarpedia.org/article/Partial_differential_equation

http://www.scholarpedia.org/article/Partial_differential_equation

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/temperature_profile.png

http://cdn.comsol.com/cyclopedia/navier-stokes-equations/pressure_profile.png

126

relations between partial derivatives of unknown fields such as temperature, concentration, pressure,

molar fraction, density of electrons or probability density function, with respect to variables within

the domain (space, time,...) under consideration.

As in the finite element method, a mesh is constructed, which consists in a partition of the domain

where the space variable lives. The elements of the mesh are called control volumes. The integration

of the PDE over each control volume results in a balance equation. The set of balance equations is

then discretized with respect to a set of discrete unknowns. The main issue is the discretization of the

fluxes at the boundaries of each control volume: in order for the FVM to be efficient, the numerical

fluxes are generally

conservative, i.e. the flux entering a control volume from its neighbour must be the opposite of the

one entering the neighbour from the control volume,

consistent, i.e. the numerical flux of a regular function interpolation tends to the continuous flux as the

mesh size vanishes.

It is sometimes possible to discretize the fluxes at the boundaries of the control volume by the finite

difference method (FDM). In this case, the method has often been referred to as a finite difference

method or conservative finite difference method (see Samarskii 2001). The specificity of the FVM

with respect to the FDM is that the discretization is performed on the local balance equations, rather

than the PDE: the fluxes on boundaries of the control volumes are discretized, rather than the

continuous differential operator.

The resulting system of discrete equations depends on a discrete (finite) set of unknowns, and may

be either linear or non linear, depending on the original problem itself; this system is then solved

exactly or approximately, using for example direct or iterative solvers in the case of linear equations

and fixed point or Newton type methods in the case of nonlinear equations.

http://www.scholarpedia.org/article/Finite_element_method

http://www.scholarpedia.org/article/Finite_difference_method

http://www.scholarpedia.org/article/Finite_difference_method

http://www.scholarpedia.org/article/Finite_volume_method#sam-01-the

http://www.scholarpedia.org/article/Fixed_point

127

APPENDIX 2

RESEARCH PROPOSAL

1. RESEARCH INTRODUCTION

With the increasing oil prices in earlier 20th

Century, requirement for more proficient performance, and efficient,

safer, ergonomic cars increased. Demand of the global greenhouse gas reduction has become one more significant factor

in the cars. This change leaded to tremendous brainstorm among car designers & manufacturers. This followed with the

significant questions regarding effect of shortage of the oil supply and the future of the automobile industry. Vivid

solutions were laid on the table which included the design of hybrid cars – electric & much more. Other proposed

approaches include the integration of air conditioning system with electronic devices to cut down energy consumption,

the redesign of car frame and body to reduce its total weight, and the modification of car external to improve the car

overall aerodynamic characteristics for better cruising conditions, greater stability of navigation, and lower energy

consumption. Feasibility of the solutions was given a second thought. The stage was turned on the focus on the

aerodynamics of car.

Aerodynamics for the cars has changed gradually from initial designers to the manufacturers’ to obtain more

power under the hood. This means more stability; better performance, better grip and most prominently increase the

Figure 1 showing the change of the drag coefficient along with years.

128

comfort of the car. People seem to have sportier look to have the best output performance. The 20th

century has seen

some of the finest sedan cars. From highest speed Hennessey Venom GT reaching up to 270.49 mph, Bugatti Veyron to

the luxurious Rolls Royce phantom and much more. Personal cars ranging from hatch backs, sedans & SUV have seen

major changes in their design and ergonomics depending on their customers’ choice. Aerodynamics plays a very crucial

role in increasing the fuel efficiency and safety of the driver. Efficiency of a car aerodynamically can be expressed by

coffieicient of drag denoted by CD while stability by CL coefficient of lift and is a dimensional less unit.

Fixing a rear spoiler at rear portion depends on shape of the rear portion whether the car is square back,

notchback or fastback because not all rear spoiler can be fixed at any type of rear portion of a car. However Rear spoiler

contributed some major aerodynamics factor which is lift and drag. The reduction of drag force can save fuel.

2. RESEARCH AIM

The aim of the research is to analyses how a rear spoiler helps in drag reduction by controlling the flow of the

air around the car body. The results obtained from the computational fluid dynamics (CFD) are validated and compared

to the model of a car designed as 2D surface in inventor with and without the spoiler.

3. RESEARCH OBJECTIVE

Understanding the drag coffieicient with the ground clearance, concepts of drag and lift in physics, pressure

distribution (Fundamentals of Physics, Resnick & Halliday), aerodynamic drag and lift acting on car, down force and

applying the above data on the model in designing and CFD to confirm the results. Using three different types of the rear

spoilers & their CFD analysis results to achieve the aim using following objectives in the research project:

Analysis of the air flow around the car without the rear spoiler.







129

Drawing out the possible outcomes comparing the results & establishing the relation of using rear spoilers for

better performance, reduced lift and drag.

4. RESEARCH LITERATURE REVIEW

Literature review should cover the basic standard principles of aerodynamics which is easy to be understood by

a layman. The equations are followed by the theory which focuses of the laws of physics and engineering of

aerodynamics governing the equations and results. This also includes the predominant theories and concepts used in the

project. Some of the concepts that will be discussed in brief in the literature review will be the following:

Basic Drag & Lift concept along with their formulas.

,

Understanding Bernoulli’s Equations for air flow over a moving object

Example of equations p + ½ ρ v2 + γ z = constant along streamline (Munson, 2006)

Elaborate understanding of the aerodynamic for Drag & Lift forces.

Pressure distribution across the surface of the car body.

Understanding the down force.

Coefficients of Drag and Lift CD & CL

Applications of the above points on a rear spoiler of a model car.

Figure 2: showing Gillespie’s experiment results showing the effect of spoiler height to the aerodynamics of car.

130

5. RESEARCH METHODOLOGY

Followed by the literature review, would be the concept generation of the rear spoilers for the cars. A survey on

design of the aftermarket rear spoiler was done by surveying several spoiler designs in market that currently most used.

Because there several type of rear spoiler in market, so this step to ensure that the rear spoiler that will be used is most

used by car’s owner.

As the title reflects Aerodynamics of a car using rear spoiler, a series of the CAD files are generated of the

different types of spoilers. This also includes the design of the model car (Bugatti Veyron) with and without the rear

spoiler along with the spoilers. All the designs are generated on the Auto Desk Inventor 2014 as 2D surface. The designs

are exported as .iges or .step file to be extracted to the CFD package. ANSYS Fluent is used to run the models for

analysis. The CFD software interprets and results the value of CD & CL which is later explained in the observations &

calculations. The obtained results are explained and plotted on a graph. Every design of the spoilers is compared to the

base model.

Wind tunnel tests are generally quiet expensive and quiet time consuming. It takes weeks of through study, while the

same effects & results can be obtained on CFD ANSYS Fluent in hours.

PROJECT LIMITATIONS

One of the major limitations of the project was the system requirements. Most of the designs were generated and

simulated on computer with 4 GB of ram. This underscored and limited the designs to be in 2D surface models. As

making in 3D would consume more memory power and the lab was equipped with only above specification computers.

One of the major dependencies were the designs were generated on the Auto Desk inventor professional 2014. The

researcher has previous knowledge of using auto desk inventor instead of the designing geometry in ANSYS Fluent. This

consumed a major time as modifications and iterations based on the basic model, the researcher had to refer back to the

initial models in the CAD format in inventor.

Although the project started with a delay in analysis, much of the major time loss was a result of the initial

geometry design.

131

6. OBSERVATIONS & CALCULATIONS

The values are interpreted and plotted on the graph. The results of the model car without and with the rear

spoiler are compared. Every different design of spoilers is compared to the base design. The final results will compared

to prove the effect of rear spoilers in reducing aerodynamic drag, lift and coefficients of drag & lift enhancing the car

performance & safety in a tabular form

7. RESEARCH CONCLUSION

Finally finishing the report with conclusion along with the project Gantt chart, future works are also included to underpin

the potentials of the further research that could be extended by potential candidates.

132

RESEARCH ETHICS APPLICATION FORM

(STAGE 1)

More information on ethics procedures can be found on your faculty website. You must read the

Question Specific Advice for Stage 1 Research Ethics Approval form.

All research carried out by students and staff at Anglia Ruskin University and all students at our

Franchise Associate Colleges must comply with Anglia Ruskin University’s Research Ethics

Policy (students at other types of Associate College need to check requirements).

There is no distinction between undergraduate, taught masters, research degree students and staff

research.

All research projects, including pilot studies, must receive research ethical approval prior to

approaching participants and/or commencing data collection. Completion of this Research Ethics

Application Form (Stage 1) is mandatory for all research applications*. It should be completed by

the Principal Investigator in consultation with any co-researchers on the project, or the student in

consultation with his/her research project supervisor.

*For research only involving animals please complete the Animal Ethics Review Checklist instead

of this form.

All researchers should:

Ensure they comply with any laws and associated Codes of Practice that may be applicable

to their area of research.

Ensure their study meets with relevant Professional Codes of Conduct.

Complete the relevant compulsory research ethics training.

Refer to the Question Specific Advice for the Stage 1 Research Ethics Approval.

Consult the Code of Practice for Applying for Ethical Approval at Anglia Ruskin University.

If you are still uncertain about the answer to any question please speak to your Dissertation

Supervisor/Supervisor, Faculty Research Ethics Panel (FREP) Chair or the Departmental

Research Ethics Panel (DREP) Chair.

Researchers are advised that projects carrying higher levels of ethical risk will:

require the researchers to provide more justification for their research, and more detail of the intended methods to be employed;

be subject to greater levels of scrutiny;

require a longer period to review. Researchers are strongly advised to consider this in the planning phase of their research

projects.

http://web.anglia.ac.uk/anet/rdcs/ethics/applicants/apply/QSAStage1.doc

http://www.anglia.ac.uk/ruskin/en/home/faculties/fst/research0/ethics.Maincontent.0020.file.tmp/animal_ethics_checklist_digitisedv.2.pdf

http://web.anglia.ac.uk/anet/rdcs/ethics/index.phtml

http://web.anglia.ac.uk/anet/rdcs/ethics/applicants/apply/COP.doc

http://web.anglia.ac.uk/anet/rdcs/ethics/about/frep.phtml



133

Section 1: RESEARCHER AND PROJECT DETAILS

Researcher details:

Name(s): Dibyajyoti Laha

Department: Engineering & Built Environment (Mechanical Engineering)

Faculty: Science &Technology

Anglia Ruskin email address: [email protected]

Status:

Undergraduate X Taught

Postgraduate

Postgraduate

Research

Staff

If this is a student project:

SID: 1227201

Course title: BEng Mechanical Engineering Honors

Supervisor/tutor name Dr. Ahad Ramezanpour

Project details:

Project title (not module title): “Computational aerodynamic analysis of a rear spoiler on

a car in two dimensions“

Data collection start date:

(note must be prospective) 1 st March 2015

Expected project completion date: 8th

May 2015

Is the project externally funded? No

License number (if applicable): No

CONFIRMATION STATEMENTS – please tick the box to confirm you understand these

requirements

The project has a direct benefit to society and/or improves knowledge and understanding. X

All researchers involved have completed relevant training in research ethics, and consulted

the Code of Practice for Applying for Ethical Approval at Anglia Ruskin University. X

The risks participants, colleagues or the researchers may be exposed to have been considered

and appropriate steps to reduce any risks identified taken (risk assessment(s) must be

completed if applicable, available at: http://rm.anglia.ac.uk/extlogin.asp) or the equivalent

for Associate Colleges.

X

My research will comply with the Data Protection Act (1998) and/or data protection laws of

the country I am carrying the research out in, as applicable. For further advice please refer to

the Question Specific Advice for the Stage 1 Research Ethics Approval.

X

Project summary (maximum 500 words):

Please outline rationale for the research, the project aim, the research questions, research

procedure and details of the participant population and how they will be recruited.

Socio-economic factors have changed with the recent years. Hikes in fuel price (BP, histogram data, 2012) and

desperate need to reduce the greenhouse gas emissions have increased since 1970 (Reuters, 1970). This has leaded the

automobile industry to rethink on their product’s efficiency, ergonomics and safety. Studies and research came up with

varied solutions like electric car or hybrid cars (Tesla Motors, 2002). Among them was rethinking and designing of the

automobiles. Aerodynamics plays a very crucial role in increasing the fuel efficiency and safety of the driver. Efficiency

of a car aerodynamically can be expressed by coffieicient of drag denoted by CD while stability by CL coefficient of lift

http://rm.anglia.ac.uk/extlogin.asp

http://web.anglia.ac.uk/anet/rdcs/ethics/index.phtml

134

and is a dimensional less unit

With the recent drop in the drag coefficient and use of more conventional methods based on the aftermarket of the cars

have increased. These methods include the regulation of the air flow around the vehicle to increase stability while driving

at higher speed and reduce drag coefficient. Rear car spoilers are one of the devices that are designed to ‘spoil’

unfavorable air movement across a car body. Fixing a rear spoiler at rear portion depends on shape of the rear portion

whether the car is square back, notchback or fastback because not all rear spoiler can be fixed at any type of rear portion

of a car. However Rear spoiler contributed some major aerodynamics factor which is lift and drag. The reduction of drag

force can save fuel.

Aim: The aim of the research is to analyses how a rear spoiler helps in drag reduction by controlling the flow of the air

around the car body. The results obtained from the computational fluid dynamics (CFD) are validated and compared to

the model of a car designed as 2D surface in inventor with and without the spoiler.

Objective: The research focuses on the basic concepts of the aerodynamics acting on the car. This includes David

Bernoulli’s equations to understand the effect of the flow of the air around a body in motion (Glenn Research Centre,

NASA, 2014). Understanding the drag coffieicient with the ground clearance, concepts of drag and lift in physics,

pressure distribution (Fundamentals of Physics, Resnick & Halliday), aerodynamic drag and lift acting on car, down

force and applying the above data on the model in designing and CFD to confirm the results. Using three different types

of the rear spoilers & their CFD analysis results to achieve the aim using following objectives in the research project.

Analysis of the air flow around the car without the rear spoiler.







Drawing out the possible outcomes comparing the results & establishing the relation of using rear spoilers for

better performance, reduced lift and drag.

Methodology: Thorough study of the spoilers available in the market is done to apply at least 3 different models of the

spoilers on the rear of the car and analyses the data on the CFD software package. Definite meshing and geometry

conditions are assigned along with the domains to find the drag coefficient value from ANSYS Fluent (CFD software).

The values are interpreted and plotted on the graph. The results of the model car without and with the rear spoiler are

compared. Every different design of spoilers is compared to the base design.

Expected Results: The final results will compared to prove the effect of rear spoilers in reducing aerodynamic drag, lift

and coefficients of drag & lift enhancing the car performance & safety in a tabular form.

Section 2: RESEARCH ETHICS CHECKLIST - please answer YES or NO to ALL of the

questions below.

WILL YOUR RESEARCH STUDY? YES NO

135

1 Involve any external organisation for which separate research ethics clearance is

required (e.g. NHS, Social Services, Ministry of Justice)?

X

2 Involve individuals aged 16 years of age and over who lack capacity to consent

and will therefore fall under the Mental Capacity Act (2005)?

X

3

Collect, use or store any human tissue/DNA including but not limited to serum,

plasma, organs, saliva, urine, hairs and nails? Contact

[email protected]

X

4 Involve medical research with humans, including clinical trials? X

5 Administer drugs, placebos or other substances (e.g. food substances, vitamins)

to human participants? X

6 Cause (or could cause) pain, physical or psychological harm or negative

consequences to human participants? X

7 Involve the researchers and/or participants in the potential disclosure of any

information relating to illegal activities; or observation/handling/storage of

material which may be illegal?

X

8 With respect to human participants or stakeholders, involve any deliberate

deception, covert data collection or data collection without informed consent? X

9 Involve interventions with children and young people under 16 years of age? X

10 Relate to military sites, personnel, equipment, or the defence industry? X

11 Risk damage or disturbance to culturally, spiritually or historically significant

artefacts or places, or human remains? X

12 Involve genetic modification, or use of genetically modified organisms above

that of routine class one activities?

Contact [email protected]

(All class one activities must be described in Section 4).

X

13 Contain elements you (or members of your team) are not trained to conduct? X

14 Potentially reveal incidental findings related to human participant health status? X

15 Present a risk of compromising the anonymity or confidentiality of personal,

sensitive or confidential information provided by human participants and/or

organisations?

X

16 Involve colleagues, students, employees, business contacts or other individuals

whose response may be influenced by your power or relationship with them?

X

17 Require the co-operation of a gatekeeper for initial access to the human

participants (e.g. pupils/students, self-help groups, nursing home residents,

business, charity, museum, government department, international agency)?

X

18 Offer financial or other incentives to human participants? X

19 Take place outside of the country in which your campus is located, in full or in

part?

X

20 Cause a negative impact on the environment (over and above that of normal

daily activity)?

X

21 Involve direct and/or indirect contact with human participants? X

mailto:[email protected]


136

22 Raise any other ethical concerns not covered in this checklist? X

Section 3: APPROVAL PROCESS

Prior to application: 1. Researcher / student / project tutor completes ethics training . 2. Lead researcher / student completes Stage 1 Research Ethics Application form in consultation with co-

researchers / project tutor.

NO answered to all questions (Risk category 1)

(STAGE 1 APPROVAL) NO answered to question 1-13 YES answered to any question 14-22 (Risk Category 2)

(STAGE 2 APPROVAL) Yes answered to any question 3-13 (Risk Category 3B)

Research can proceed. Send this completed form to your relevant DREP for their records.

i) Complete Section 4 of this form. ii) ii) Produce Participant Information

Sheet (PIS) and Participant Consent Form (PCF) if applicable.

iii) Submit this form and PIS/ PCF where applicable to your Faculty DREP (where available) or Faculty FREP. Two members of the DREP/FREP will review the application and report to the panel, who will consider whether the ethical risks have been managed appropriately.

• Yes : DREP / FREP inform research team of approval and forward forms to FREP for recording.

• No: DREP / FREP provides feedback to researcher outlining revisions required.

The panel may recommend that the project is upgraded to Category 3 - please see below for procedure.

Complete this form and the Stage 2 Research Ethics Application form and submit to your FREP. FREP will review the application and approve the application when they are satisfied that all ethical issues have been dealt

Yes answered to question 1 and / or 2 (Risk Category 3A)

Submit this completed form to your FREP to inform them of your intention to apply to an external review panel for your project. For NHS (NRES) applications, the FREP Chair would normally act as sponsor / co-sponsor for your application. The outcome notification from the external review panel should be forwarded to FREP for recording.







137

Section 4: ETHICAL RISK (Risk category 2 projects only)

Management of Ethical Risk (Q14-22)

For each question 14-22 ticked ‘yes’, please outline how you will manage the ethical risk posed by

your study.

Section 5: Declaration

*Student/Staff Declaration

By sending this form from My Anglia e-mail account I confirm that I will undertake this project

as detailed above. I understand that I must abide by the terms of this approval and that I may not

substantially amend the project without further approval.

**Supervisor Declaration

By sending this form from My Anglia e-mail account I confirm that I will undertake to supervise

this project as detailed above. *Students to forward completed form to their Dissertation Supervisor/Supervisor.

** Dissertation Supervisor/Supervisor to forward the completed form to the relevant ethics

committee.

Date: August 2014

V 5.2

138

CV, Cover Letter and Exit Plan

CV - Dibyajyoti Laha

G.P.A. 1st Year : 3.38/4.0 120 Credits Completed.

G.P.A. 2nd Year: 3.86/4.0 120 Credits Completed

Dibyajyoti Laha Flat above no 8., 10 B Broomfield Road. Chelmsford

Essex, England, U.K. CM1 1SN

M (+44 074 638 98808) Email : [email protected]

CAREER OBJECTIVE

Seeking opportunities in Mechanical/ Manufacturing Engineering (Specialize in Design, Production, Procurement & Management)

AngliaRuskinUniversity, Chelmsford, England, U.K. Course:

EDUCATION Institutes:

BEng Mechanical Engineering Honours. (Pursuing 3rd Year) Date of completion:

Expected 30th May 2015.

Foundation: Manipal University &Kurukshetra University, India

Course : BE Mechanical Engineering (A Levels and Foundation respectively)

Percentage: 74.5%

> Mathematics 1 & 2

RELEVANT COURSEWORK

> Mechatronics

> Manufacturing

> Applied Mechanics > Engineering Materials > Statics & Dynamics

> Fluid Mechanics > Thermodynamics > CAM & Auto CAD

> Heat Transfers > Applied Software > Process Quality

> Technology Projects > Environmental Sciences > Engineering Physics 1&2

> Modelling and Simulation for Operation Management > CAE Ansys Workbench > Engineering Management. > Stress & Dyanmics > Learning skills for HR & work

> Thermofluids.

ENGINEERING INTERNSHIPS / WORK EXPERIENCES

2007- NASA - ISSF internship, JohnsonSpace Centre, Houston, Texas, U.S.A.

Position: Aerospace Design Intern (Engineering)

Brief : Used AutoCAD to design rovers and parachute systems in the rocketry. Made 2D drawings for the

mission and presented powerpoint presentations of the project. The project was declared successful with a

graduation certificate from Astronaut Nicole P Scott in association with Jet Propulsion Laboratory. Networking

and teamwork were a major part of the internship program along with management roles in the project.

2010 - ThyssenKruppEngineering, Germany.

Position: Mechanical/ Constructional Engineering

Brief : Internship with ThyssenKrupp was more focused with the Deputy Site Manager. Performed surveys

on material engineering, procurement and production line of a large scale refinery plant along with

Engineering management in industry. Design of the prototypes and run descriptions. Lean Manufacturing skills

Like SPC, SPOIC, Lean factors, KANBAN

2011 - AdityaBirlaEngineering Ltd. India, Mumbai, India

Position: Mechanical / Built Construction Engineering (ALUMINIUM production unit)

Brief : Solved engineering problems on designs analysis, Gained exceptional problem solving, communication

leadership and interpersonal skills. Faced actual customer projects and real time responsibility.

Design Analysis, engineering sales, (for details on project please refer my linkedin account)

November 2013 - Hewlett Packard(HP Microsoft- CPM). Essex, UK,

Position : HP - Microsoft training and office products analyst at Currys PC World. Increase microsoft software

awareness.



Nov 2013 - January 2014 SONY Electronics, UK. Essex.

Worked as Sony’s business analyst for home theatre systems and television technology at

Currys PC World. Engineering Sales, audits, head office compliances and

January 2014 - Till date VAXUK – TTI FloorCareNorthAmerica . Essex

Description:

VAX - TTI Floorcare North America are currently the No 1 best-selling floorcare brand in the UK. With a rich

heritage and growing global position, we are a market-leader in floorcare innovation. Not only that, Vax is one of

The Sunday Times Top 100 Best Companies To Work For 2014 and the only floor care equipment manufacturer

business on the list!

Vax Commercial is fast becoming a highly respected and revered brand within the Commercial / Professional

sector in the UK, achieving phenomenal growth in the last year with the introduction of new products & industry

leading marketing campaigns.

The role

An excellent opportunity in commercial team to support the Commercial and Engineering sales function with

new and on-going projects and all associated activities appropriate to major accounts and building relationships

with major accounts’ key personnel. Engaging heavily with the sales team in store and be involved in the

effective running of the team day to day. This role is varied and offers a breadth of exposure to commercial areas

in the business.

Responsibilities will include:

Day to day account activity

Management of new and on-going projects and product launching

Processing product samples of in-warehouse products and maintaining sample log

Documentation, origination and co-ordination of sales and marketing data

Problem solving at customer interface with major accounts

Presentation support – including key account materials and analysis, manipulation and graphic representation of

market data

Assisting in organisation and preparation for exhibitions, trade shows and displays for major accounts

Maintenance and production analysis.

Product demonstration, training, auditng, Merchandising & aggressive marketing the new designed products for

VAX one of the TTI companies. Demonstrations, audits and feedback to HQ.

June 2014 – Till date Eppendorf CryoTech UK. (A subdivision of Eppendorf AG, Hamburg Germany)

Company background

Eppendorf CryoTech, Maldon, UK, is part of a group of leading life science companies that develops and sells

instruments, consumables, and services for liquid-, sample-, and cell handling in laboratories worldwide.

Products are most broadly used in academic and commercial research laboratories, e.g., in companies from the

pharmaceutical and biotechnological as well as the chemical and food industries. They are also aimed at clinical

and environmental analysis laboratories, forensics, and at industrial laboratories performing process analysis,

production, and quality assurance.

The company specializes in the design and manufacture of ultra-low temperature freezer products, which are

distributed world-wide.

Project details

Working with the manufacturing area manager and supervisors to assist in the data collection and analysis of the


assembly steps from receipt of component parts through the sub-assembly stages to final

assembly, finished product test, product clean and pack, ready to ship to finished product

warehouse for subzero temperature freezers.

Assisting with generating simple data collection documentation templates to assist in the effective

collection of work center efficiency data, and involved in the analysis of data and in the review and

recommendations for reduction in waste and efficiency improvements.

Development Focus

Eppendorf CryoTech, Eppendorf AG hopes to significantly improve the efficiencies in their

manufacturing process and reduce their waste in materials. Also to gain production data,

introduce standards and optimise production time. Therefore, this is an excellent opportunity to

really make a difference at this very busy time. Getting strong hands on experience in an

engineering/manufacturing environment.

March 2015 - Till date Computational aerodynamic analysis of a rear spoiler on a car in two dimensions:

Anglia Ruskin University.

It included the design of the model car BMW 3series and analyze the air flow around the body in

2D.

Apart from designing it included the use of ANSYS CFD tool to study the air flow.

March 2015 – Till date Nespresso

Nestle – UK

Field Sales

Engineering

Core brand team of over 140 permanent executives throughout the UK & Ireland Created an industry

leading reporting app that centralizes working schedules, GPS tracking to monitor

compliance, sales reporting tools and incentivized training modules to further

develop brand knowledge Nespresso’s exclusive consumer facing app enables

consumers to order coffee and sign up to the Nespresso’s Club at point of purchase

A tailor made recruitment and induction program that

Includes a 2 day training schedule for all new starters and refresher courses for existing

demonstrators Designed a bespoke, premium uniform to create stand out in-store Delivery

of experiential events in shopping centers across the UK

Additional Experience: AngliaRuskinManufacturing Workshop: Construction of working hot air engine, machining,

assembly AngliaRuskinSoftw areDevelopment: Coded and worked on CNC machines

software and development. CPM UnitedKingdom&Channel AdvantageUK : Performed

management operational duties across Essex.

CPM UnitedKingdom, HP Campaigns : Event manager at HP campaigns at PC Currys world

across Basildon, Essex. .

MASHStaffing UnitedKingdom: Worked as manager for momentum ASDA Harlow for Halloween.

Invited Student Experience: Goldman Sachs. London, United Kingdom. 2013

Invited to experience the culture of the organization and the working of technology infrastructure

TECHNICA

L SKILLS

> Project management > SAP manufacturing ERP > Solid Edge >Solid works

> Health and Safety training. > Welding Process & Theory > Designing > Rapid

> Lathe Machining & CNC operations > Metal Fabrication > Milling > Basic Hand tools

> Microsoft Office > KANBAN (JIT) > Operating Systems (Mac., Microsoft > C, C#, C++ &

> Adobe > Safety Handouts > Sig Sigma Belt for Manufacturing


HONOURS

● 9th position in International Science Olympiad

(Gold medal)

● High School Secretary

CERTIFICATES

● Safety & Health in Construction (Irish Certificate)

● Diploma in Fine Arts & Painting

● Diploma in Workplace Safety & Health

● Diploma in Project Management.

● Diploma in Human Resource Management.

PERSONAL STATEMENT

Born and raised in the family of an engineer. Throughout high school and college, my father a construction mechanical engineer has been an

ideal person for me. At school I was fascinated about aerospace and spent a year as a design intern at NASA, grew up as teenager with interest

in oil and gas in mechanical, did welding, milling, casting, forming in a small workshop. In the summers of high school worke d as intern in

ThyssenKrupp India, analysed the designs of lifts, constructions, designs to development of a product. In nut mechanics and its engineering

runs in my veins. I am an inquisitive person by nature and like to learn more.

MEMBERSHIPS

● Student Member of IET (Institute of Engineering & Technology)

● Student Member of CIOB, UK (Chartered Institute of Building)

● Permanent member of IAC, France (International Aeronautical Congress)

● Alumni of NASA - ISSF, Texas, U.S. (International Space School Foundation)

● Member of SAE International.

REFERENCES

Dr. Ahad Ramezanpour (Academic)

Mr. Dilip Kumar Laha. D.S.M. Jacobs Engineering India (Colleague)

Dr. Mathias Schumann (Professional)

Available upon request

SOCIAL NETWORK

Linkedin: uk.linkedin.com/pub/dibyajyoti-laha/54/303/122

Skype : Netmash.inc

http://uk.linkedin.com/pub/dibyajyoti-laha/54/303/122

1 Dibyajyoti Laha Exit Plan

Future Aspects

Exit Plan

Thermofluids (MOD002684)

This module gave a theoritical approach to the study of thermodynamics but, at the same time it is a very practical subject to understand fluids and heat laws.Studying this module enabled me to grasp a better understanding of the following topics :

· First law of thermodynamics

· Properties of liquid and vapor, properties of gas

· Second law of thermodynamics

· Reciprocating air standard cycles

· Chemical reactions, combustion

· Fundamentals of heat transfer

· Combined heat transfer modes

· Fundamental of fluid mechanics, fluid statics

· Fluid dynamics, steady flow process and momentum equation

· Steady flow energy equation, dimensional analysis

Apart from the standard theoritical concepts, the final assignment for this module dealt with the Air re-circulation inside a freezer, which focused on the application of a software ANSYS CFD (Computational Fluid Dynamics) & EnSight 10.1 to understand a products thermodynamic behavior.

Learning Outcome

Looking for future in mechanical Engineering this module will play an active role . I personally look forward to work in Oil & Gas production, where this module would play a very active role.

Materials and Processes (MOD002634)

The module is a legitimate approach towards better understanding of the composite engineering and important aspects of engineering materials if as mechanical engineer, the candidate wants to per-sue his career in the field of process engineer or design engineer. The module course outlined the study on the following topics and is an advanced level of the module Introduction to Engineering Materials

Behavior of engineering material under stress.

Effects of heat on materials, heat treatment of engineering materials and phase diagrams

Stress concentration and finite element analysis

Fatigue

Creep

Stress corrosion

Corrosion and degradation

Principles of composite design and applications

Economics of manufacture processes

Effects of manufacturing method on material properties including grain flow, residual stresses, etc

Manufacturing processes including casting, forging, pressing, welding

Re-cycling of materials

Learning Outcome


Future Aspects

Apart form the standard theoritical knowledge, the module gave market experience about the studies with two iconic industrial visits to leading composite material manufacturing companies - Encocam UK Ltd & an American company - TruckLite. The module encouraged visiting lecturers and guest speakers on the application and broader spectrum

Introduction to Engineering Materials (MOD002565)

This module improved the basic regarding to structure and properties of a range of engineering materials. It also improved the knowledge about laboratory work where tensile tests were done for different materials in different experiments

Atomic configuration of metals and non metals

Bonding in metallic and non metallic materials

Simple concepts of alloying

Single and binary alloy systems

Equilibrium and non equilibrium transformations.

Precipitation alloys

Electronic structures of insulators ,semi conductors and conductors with reference to energy gap

Valency band and conduction band

Structure and application of polymeric materials

Learning Outcome

Future Aspects

The module is a pre requisite for the module Materials and Process. This module not only enhances the basic understanding of material science and properties but also gives a standard idea of the industrial tests which would be needed in the future or while at job.

Mathematics for Engineering (Year 1 & 2) (MOD003214 ,

MOD002306)

The modules included the standard mathematics for engineering touching and explaining the theoritical mathematics.

Learning Outcome

Matrices, Integration, differentiation, Basic geometry maths, applied mathematics and statics probability. Along side in the module for Maths in year 2 focused on the more vital aspects of the hand in calculation of the differentiation and integration, Lagrangian formula, Taylor series, Fourier series and heat maths and probability. Statistics in the construction industry, linear regression, Normal distribution, Determinants, Matrices. In fine, it was really an important module to solve difficult problems regarding to engineering calculations.

Future Aspects The module gives a better understanding in the everyday technology maths. Applications involve in plenty of the subjects like Thermofluids (standard 2nd order differentiation, Double integration for heat and work calculation, using the matrix based formulas on FEA analysis ) and much more.

Mechatronics (MOD002584)

A combination of two disciplines : mechanical and electrical. A always demanded module for an overall understanding of electrical and mechanical products.


Future Aspects

Future Aspects

Learning Outcome

In mechanical part, it was all about mechanical behavior and its calculation on pulley, gears, cam, bulb etc. On the other hand, electrical part was about electrical components description and calculation as well as it helped to teach the using of software called Multisim which can be used to draw circuit connection and to observe the behavior of resistor, voltage, current etc. by changing some components inside the circuit connection like, diode.

Future Aspects This module can play an active role in the future specific job roles like automation and production engineers where constant communication is needed between the electrical parts and the mechanical products like gear box in a car and the dash board display.

Applied Software

(MOD002561) Module based on the basic understanding and practical application of coding any software using C and C++

Learning Outcome

Applied software focused on the learning of the basic programming language called C. This included on the programming for basic and complex. The assignment included designing a ticket vending machine based on the platform of C. In nut this module gave on additional experience to the mechanical engineers to have practical experience on coding.

With the knowledge of this module, it would be easy for mechanical engineers to code software or platform for any opertions related to computer performance . Fopr example using a CNC machine.

Manufacturing (MOD002554)

The module manufacturing focused on the understanding of the manufacturing world. This included the simple steps and process involved for the product to come to market from the raw/ initial stage.

Learning Outcome

Manufacturing module taught to design and work in a workshop with machines like CNC machine and Lathe. Other applications of the study included the basic foundry shop applications like moulding, casting and hand axes and trimming, filing. It was a first module which helped to teach how a group work is important and how to work in a group.

This module provided a broad spectrum of the knowledge required for the production - mechanical manufacturing companies.

Engineering Principles

(MOD003120) An more elaborate module on better understanding of the year 1 Mechatronics.

Learning Outcome

The electrical section consisted of the resistor, inductor, capacitor, voltage and current relationships in dc and ac circuits and Kirchhoff’s laws relating to dc and ac circuits and thevenin. The mechanical discipline dealt with the calculation of forces, velocity, acceleration, distance, moments. The assignment consisted on the theoritical research in a summarized set of questions based on the practical experience in the laboratory too.


Future Aspects

Future Aspects

Future Aspects More understanding on the subject of statics and Dynamics of bodies in applied mechanics

Statistics and Process Quality Assurance

(MOD002607)

A module designed to deliver the potentials of running a Quality control in an organization, understanding the need and techniques invloved in it.

Learning Outcome · Understanding the Quality management systems and standards e.g. ISO 9000. & ISO 140001

· Improving the technical and non technical quality technique including Pareto, cause and effect diagrams, Shew cycle, etc.

· Probability and statistics including: sampling, graphical representation of data, regression, binomial, Poisson and normal distributions, measures of location and spread, expected values hypothesis testing, correlation.

· The role of inspection including costs and risks.

· Constructing & interpreting statistical process control charts including the following types: attribute, average and range, average and standard deviation, moving average/moving range, multi-stream .

· Assessment of process capability and calculation of expected reject rates.

· The module will also give an appreciation of the wider aspects of quality management that are vital to the survival of all organizations

· Understand the function and importance of quality assurance in the organization and management of a company.

The module is an important course in the field of engineering as well as in non technical. This module helps in understanding how to improve the profitability and meeting quality standards.

Applied Mechanics (MOD002616)

It was a study of the statics and dynamics of particles and rigid bodies under the influence of forces. It can be said that this module was proper physics. This module mainly dealt with shear force for simple beams and bending moments including analysis of simple stress cases with shear and normal stress.

Learning Outcome

Understanding Pin joint forces, Dry friction motion on horizontal and inclined plane, Shear force and bending moment diagrams; simply supported and cantilever beams. Better understanding of the Mechanisms; velocity diagrams, four bar chains reciprocating mechanisms, Static And Dynamics of fluids concept of head; Bernoulli equation, flow through pipes venture meter an dynamics

Applied Mechanics is a module which focuses on the knowledge of the structural mechanics, understanding the construction forces. This is an ideal subject for mechanical construction or field based mechanical jobs.


Learning Outcome

Future Aspects

Computer-Aided Solid Modelling (MOD002610)

As the name says, this module was an interactive approach and assessment based course which developed the skills of designing any 3D product on 2D and generate the 3D structure of it.

This module focused on the use of the software Auto Desk inventor professional for designing the product. Basic 2D sketches, Basic applications of assembling multiple parts, extrusion, filing and riveting designs.

Future Aspects This module helped to design my own product for the assessment " A kid's scooter" . Even this module helped to generate product for CAE analysis and CAM . In nut the module provided an interactive approach to build and design own products.

CAE (Computer Aided Engineering) (MOD002656)

One of the finest and most demanded subject, CAE plays an active role in shaping engineering products. CAE offers an interactive software learning used in commercial industry.

Use of ANSYS Workbench 15.

Product research

Analysis of the static stress

Application of effects of stress

Generating CAM code for the physical product production in workshop

Comparisons of the physical part test and ANSYS Workbench results

Learning Outcome

CAE as a module can be used in FEA (Finite Element Analysis) industry, product development. Further studies of CAE can include subjects like AEROSPACE - NASA (nastran) and much more in everyday engineering. -

Stress & Dynamics

(MOD002668) A subject focused on the theoritical knowledge of the application of stress and vibrations on moving objects.

Learning Outcome Vibrations

Stress & Dynamics of the moving and static objects

Basic understanding of the laws and second order differentiation

Spring formulas and example

Design of the paper straw bridge.

Future Aspects The further prospects of this module is to gain more wide application in engineering construction.

Modelling & Simulation for Operations Management

(MOD002665)

A subject which is a non technical aspect but helps engineering in determining profit, costs, labor and budgeting


Future Aspects

Learning Outcome Operational issues

Manufacturing Industry application of Modelling and Simulation.

Description in flow chart

Generating model

Running model and find best possible outcomes.

Future Aspects The module can help engineering to run softwares for budgeting and running profit. The wide applications include softwares like info32, LN Info which records and makes modelling and simulations easy. Other software includes SAP ERP

Project Management for Technologists (MOD002666)

A non technical subject focused more on the applications of HR and management strategies to be learnt at university level. The subject focused on the engineering management point to increase efficiency of an organization.

Planning & Control of projects Operational research techniques

Use of Microsoft Project

Generating budgets

Learning Outcome

Future Aspects As a future role this module can be helpful to be a part of engineering management decisions in real life industry.

Research Methods & Individual projects for

Mechanical Engineering (MOD002387)

This module is focused on generating a piece of research report for undergraduate thesis.

To generate literature review

Present and conduct a research with a supervisor

Generate a piece of research (academic report) of 10,000 word that included the 2d study of the car rear spoiler aerodynamics by the use of ANSYS CFD tool.

Learning Outcome

This module allows the students to understand the format of IET based report writing and conduct similar reports while in actual engineering jobs.

Group Design Project (MOD002309)

A module that encouraged team work and application of research ideas in engineering field. The module also helped students to understand of selecting, conducting and soluting a research project.

Feasibility of a project Selection of project

Market Research

Pugh Chart

Learning Outcome


Research report

Use of chart based selection methods

Presentations & patenting individual research

Future Aspects Future applications include real life understanding of selecting a project

Learning & Skills Development for HE & Work

(MOD002579)

A non technical module similar to Project Management. It focused more on application of different organization skills, encourage use of internet and blogging, better understanding of a difference between an essay and technical report as well as an academic report.

Understanding report writing

understanding copyright

Internet & Blogging

Presentation

report and plagiarism

Learning Outcome

Future Aspects This module gave an introspect how to write an academic report, referencing and help to curb plagiarism

With the complete 3 years of the study, the modules have enabled me to get a better and dynamic picture of the Engineering world and look forward to implement the broader ideas studied or gained from these modules in the organization I look to join.

Its a dream come true and a start to a proper full time professional mechanical engineering career.

To, The recruitment Agency Dear Sir/ Madam Subject: Actively looking for Engineering roles in Production/ Mechanical Engineering/ Design Engineering in DONG Energy. I am Dibyajyoti Laha, an international undergraduate student from India in Mechanical Engineering at Anglia Ruskin University. I have recently finished my 2nd year in Mechanical Engineering with 1st division scores in core subjects of Mechanical Engineering. I come from an engineering background. My engineering course of mechanical engineering undergraduate at Anglia Ruskin consists of modules: Thermodynamics, Fluid Mechanics, Environmental science, Heat transfers and manufacturing engineering, Engineering Mathematics and flow chart design for process, Data analysis. I am humble to say that I finished my GSC with 86.5 % in STEM and Foundation in BS Mechanical with 74.5% I started growing my interests in manufacturing industries since the age of 15. Alongside studying in my GSC levels I applied for internship with NASA - JPL (National Aeronautics & Space Administration in collaboration with Jet Propulsion Laboratory) based in Houston, Texas, US. I spent an extensive couple of months in practising and designing rovers to be sent to Mars by NASA for research projects. My skills enhanced in aerospace designs and tailored/ customer engineering including generating designs on Inventor, test runs and model demonstrations along with propulsion systems. Simultaneously I had presented the project with my team to an astronaut Nicole P Scott, who was our supervisor and received a graduation certificate with the completion of the mission. Quiet acquainted with Engineering manufacturing, I followed up in a tradition of gaining more work experiences. My project with ThyssenKrupp Engineering Germany was in manufacturing gave me ample experience in the design generation, market analysis, use of the structural analysis and successful run of the test products on AutoCAD for analysis. I again spent time in an Indian MNC brand Aditya Birla, based in Mumbai India. This gave me hands on experience in skills involving procurement, management, and application of 6 sigma techniques. I also gained experience with, batch production, mat lab and computer aided manufacturing. While studying in the UK I decided to gain experience with the market of England. I joined one of the largest global work forces sales and marketing company’s CPM where I was involved in consumer product analysis, training, feedback and complaints with the HQ, following up I wanted to practice more in the core engineering sector. Sony UK was an opportunity to work closely with the sales and engineering experiences but due to restriction of contract I had to switch to VAX UK where I am presently working part time with Curry’s Colchester in training and development of the products, demonstrations, consumer awareness and design analysis. Use of Microsoft office for data predictions and collection, spread sheet, work and access were involved in work reporting. I decided to opt for mechanical engineering as a core sector to achieve my aspirations in manufacturing and design. I recently studied and made live practice in subjects like Materials and Process, Engineering design and Analysis, Human factors in Ergonomics, Industrial process quality and control and mechatronics. My 2nd year research project at university on Hydrogen Gas Turbine was well appreciated by Siemens Energy UK student research which can be found on slide share along with my other projects. For the last 6 months I have been working as a Production Optimisation Engineer intern(first 3 months) and production engineer (presently) at Eppendorf CryoTech UK, a part of Eppendorf AG. The placement has been an ideal dream job. From day to day timing, optimising with lean techniques, Kaizen methods for efficient production, the placement has amazed me with the potentials involved working with Eppendorf. I am finishing my university course with an honours degree in 2:1 by May 2015. I am a hardworking and ambitious Engineering undergraduate, who is a team player with excellent time management skills. I am intellectually curious and a quick learner and would love to have the opportunity to extend my experience by working with the Organization. Sincerest Regards Dibyajyoti Laha