CDA WorkshopPhysical & Numerical Hydraulic Modelling

STAR-CCM+ Presentation

ENGINEERING

SIMULATION

CFDFEA

Mission

Increase the competitiveness of companies

through optimization of their product

development using engineering simulation.

Lx Sim Services

–Engineering Simulation

Outsourcing

–CAE-Intensive Product Design

– Training

4

Softwares

• CFD

– STAR-CCM+

– AcuSolve

• FEA

– HyperMesh/RADIOSS

– HyperCrash

– DesignLife

• MBD

– MotionSolve 5

• Optimization/DOE

• OptiStruct

• HyperStudy

• Process

• HyperForm

• HyperXtrude

• Moldex 3D

• Post-Processing

• FieldView (CFD)

Sample Projects

• DFBI - CFD

• Trim and Drag Prediction on Ship Hull

6

Sample Projects

• Non-Linear FEA

• Prediction of Plastic Deformations on Frame

7

Sample Projects

• Heat Transfer / Solar Radiation / Porous Baffle – CFD

• Automation of Solar Air Heater CFD

8

Outline

• STAR-CCM+ Overview and Capabilities

• Modeling and simulation procedure

• Limitations and known problems

• Case Study

• Questions 9

STAR-CCM+ Overview &

Capabilities

• CD-adapco is the largest privately owned CFD

company

• STAR-CCM+ GUI is java based, code is C++

– Very flexible

– Customization possible

– Java macro system

• Finite volume method

10

STAR-CCM+ Overview &

Capabilities• General purpose CFD

– Multi-Physics

• CAD package

• Multiple meshing

approaches

• Included post-processing

• Optimization 11

Complete Solution from

CAD to Post

12

GUI Presentation

• Tree-based

management

• Graphical

window

• Output

• Properties

13

Tree-Based Management

14

CAD Preparation

• 3D-CAD

– Creating or modifying geometries

– Similar to any sketch based package

– Somewhat limited

– Exposing design variables

• Operation History

– Boolean

– Meshes

– Adds repeatability

15

Wrapper and Surface

Repair

16

Before After

Meshers

• Trimmed cell

• Polyhedral

– Embedded thin

• Tetrahedral

• Prism

• Thin mesher

• Refinement

– Volume

– Surfaces

– Edges

17

Physics

– Multiphase

• Lagrangian

• Eulerian

• VOF

• DEM

– Conjugated heat transfer

– Shell modeling

– Chemistry

• Combustion

• DARS

– Optimization solver

– Adjoint solver

18

– Electrochemistry

– Electromagnetism

– Overset meshes

– Radiation

– Aeroacoustics

– Batteries

– Casting

– DFBI

– FSI

• Solid stress

• Direct coupling

DAM Related Models

• VOF for multiphase

- Cavitation

- Particle transport and interaction DEM

- Erosion model

• Moving parts, rotation, translation

• Multiple meshes approach

19

Cons

• No aeration by default or custom

- Surface data not accessible during

calculations

• Babysitting necessary

– Tweaking of interface solvers

– Mesh dependency

- Large mesh

- Long transient analysis

20

Case Study – Modelling

Method

21

Geometry Preparation

• Create top

boundaries

• Operations to

split in 3 regions

– Inlet

– Spillway

– Outlet

22

Meshing

• Trimmed cells

– Known surface

– Fast

• Mesh alignment

• Y+ between 10 and 150 targeted

• Refinement for interface

• Final mesh:

– Convergence not fully obtained

– Constraint in time and CPUs

• Use of relative to base size values23

Mesh - 0.52Hd - 2.7M

24

• Base size at 15m

• Medium transition in

volume

• Surface

• 0.375m in inlet and

outlet regions

• 0.15 m in spillway

Mesh - 0.52Hd - 4.4 M

25

• Base size at 15m

• Medium transition in

volume

• Surface

• 0.375m in inlet and

outlet regions

• 0.15 m in spillway

Physics Model

• VOF multiphase

• Turbulent

– All y+ treatment

• Transient analysis

• Use of VOF wave to

specify reservoir levels

and inlets

26

Initial Conditions

27

Boundary Conditions

28

VOFWave

Pressure

Solver Set-Up and

Convergence

• Multiple mesh approach to save computation time

• Time step 0.01s to 0.05s

– Settings available to increase accuracy for C >1

– Stability issue

• 5 iterations per time step

• Presence of oscillations in solution flow rate

– Potential mesh vs timestep problem

– Choice made for time constraints vs accuracy29

Case Study

1.5 X Design Head

30

• Q = 601 m3/s

• Maximum elevation at

224.2 m

Velocity

31

Velocity

32

Relative Pressure

33

Relative Pressure

34

Froude Number

35

Turbulent Kinetic Energy

Generating Air Entrainment

36

Air Entrainment at

Surface Only

37

• Creation of field functions to find location air

entrainment

• Exportation of the approximate surface

• Importation of the surface as a fluid region

• Interpolate functions on it

• Calculate aeration

• Attempted transport without success

Air Entrainment at

Surface Only

38

Case Study

0.52 X Design Head

39

• Q = 115 m3/s

Velocity

40

Velocity

41

Relative Pressure

42

Relative Pressure

43

Froude Number

44

Turbulent Kinetic Energy

Generating Air Entrainment

45

Air Entrainment at

Surface Only

46

Questions?

Wrong BC??