Boiling of Water

Tutorial 20. Boiling Water in a

Container

Introduction: The objective of this tutorial is to demonstrate thesetup and solution procedure for a two-phase ow with heat andmass transfer. In this tutorial you will learn how to:

� Explicitly allocate main memory

� Use the Eulerian multiphase model, including submodels forheat and mass transfer

� Solve a time-accurate transient problem

� Save data �les automatically during the time-dependent cal-culation

Prerequisites: This tutorial requires a basic familiarity with FLU-

ENT. You may �nd it helpful to read about Eulerian multiphase

ow modeling in Chapter 9 of the FLUENT User's Guide. Other-

wise, no previous experience with multiphase modeling is required.

Problem Description: The problem to be solved in this tutorialis depicted in Figure 20.1. Initially, the container contains wa-ter (the primary phase) at a temperature near the boiling point(372 K). The center portion of the container's bottom wall is ata temperature higher than the boiling temperature (573 K). Be-cause of conduction, the temperature of the uid near this wallwill increase beyond the saturation temperature (373 K). Vaporbubbles will form and rise (due to buoyancy), establishing a pat-tern similar to a bubble column with vapor escaping at the outletand water recirculating in the container. Changes in the diameter

Boiling Water in a Container

of the vapor bubbles will be modeled using the \shadow" methoddescribed in the FLUENT User's Guide.

T=573 K

adiabatic walls water

T =372 Kinit

vapor bubblesform and rise

Figure 20.1: Problem Speci�cation

Preparation

1. Start up FLUENT.

20-2 c Fluent Inc. May 22, 1997


Step 1: Allocate Memory

In this tutorial you will use a 60� 20 grid, and no species or reactions.

Since the default allocation will be for more memory than you need, you

can reduce the main memory allocation. This will free up memory for

the multiple phases that you will enable later in the tutorial.

De�ne�!Allocate...

1. Set theMax. Number of Cells to 1200 and theMax. Numberof Species, Reactions, and Particle Injections to 1.

2. Click OK.

c Fluent Inc. May 22, 1997 20-3


Step 2: Grid

1. De�ne the domain.

De�ne�!Domain...

(a) Set the Dimensions and Number of Cells to the valuesshown in the panel above.

(b) Click Apply and close the panel.

FLUENT will create a uniform grid for the speci�ed domain.

2. Display the uniform grid (Figure 20.2).

Display�!Grid...



Select all Zones and click on Display.

Grid ( 19 X 59 )Fluent Inc.Fluent 4.40Jul 17 1996Y

XZ

Figure 20.2: The Uniform Grid for the Boiling Water Calculation



3. De�ne the cell types.

The cells are initially set to be W-WALL cells with Zone ID 1 on

the periphery, and LIVE cells inside. You will set the cells for the

outlet and for the heated portion of the bottom surface.

De�ne�!Cells...

(a) Click on the Display button to display the cells on thisplane in the graphics window.

(b) Set the cell types for the outlet and heated wall surfaceaccording to the following table:

I-Values J-Values Type ID2{19 60 OUTLET {5{16 1 W-WALL 2



i. Use your left mouse button to select the cells in agiven group in the graphics window (e.g., select thecells with I values from 2 to 19 and a J value of 60to de�ne the outlet).

ii. Select the appropriate Type and ID in the Set Cellspanel, and click on Apply.

4. Con�rm that the cells have been properly set.

SETUP1�!LIST-CELLS



(SETUP1)-

LC

CELL TYPES:

J I= 2 4 6 8 10 12 14 16 18 20

60 W1 O O O O O O O O O O O O O O O O O OW1 60

59 W1 . . . . . . . . . . . . . . . . . .W1 59

58 W1 . . . . . . . . . . . . . . . . . .W1 58

57 W1 . . . . . . . . . . . . . . . . . .W1 57

56 W1 . . . . . . . . . . . . . . . . . .W1 56

55 W1 . . . . . . . . . . . . . . . . . .W1 55

54 W1 . . . . . . . . . . . . . . . . . .W1 54

53 W1 . . . . . . . . . . . . . . . . . .W1 53

52 W1 . . . . . . . . . . . . . . . . . .W1 52

51 W1 . . . . . . . . . . . . . . . . . .W1 51

50 W1 . . . . . . . . . . . . . . . . . .W1 50

49 W1 . . . . . . . . . . . . . . . . . .W1 49

48 W1 . . . . . . . . . . . . . . . . . .W1 48

47 W1 . . . . . . . . . . . . . . . . . .W1 47

46 W1 . . . . . . . . . . . . . . . . . .W1 46

45 W1 . . . . . . . . . . . . . . . . . .W1 45

44 W1 . . . . . . . . . . . . . . . . . .W1 44

43 W1 . . . . . . . . . . . . . . . . . .W1 43

42 W1 . . . . . . . . . . . . . . . . . .W1 42

41 W1 . . . . . . . . . . . . . . . . . .W1 41

40 W1 . . . . . . . . . . . . . . . . . .W1 40

39 W1 . . . . . . . . . . . . . . . . . .W1 39

38 W1 . . . . . . . . . . . . . . . . . .W1 38

37 W1 . . . . . . . . . . . . . . . . . .W1 37

36 W1 . . . . . . . . . . . . . . . . . .W1 36

35 W1 . . . . . . . . . . . . . . . . . .W1 35

34 W1 . . . . . . . . . . . . . . . . . .W1 34

33 W1 . . . . . . . . . . . . . . . . . .W1 33

32 W1 . . . . . . . . . . . . . . . . . .W1 32

31 W1 . . . . . . . . . . . . . . . . . .W1 31

30 W1 . . . . . . . . . . . . . . . . . .W1 30

29 W1 . . . . . . . . . . . . . . . . . .W1 29

28 W1 . . . . . . . . . . . . . . . . . .W1 28

27 W1 . . . . . . . . . . . . . . . . . .W1 27

26 W1 . . . . . . . . . . . . . . . . . .W1 26

25 W1 . . . . . . . . . . . . . . . . . .W1 25

24 W1 . . . . . . . . . . . . . . . . . .W1 24

23 W1 . . . . . . . . . . . . . . . . . .W1 23

22 W1 . . . . . . . . . . . . . . . . . .W1 22

21 W1 . . . . . . . . . . . . . . . . . .W1 21

20 W1 . . . . . . . . . . . . . . . . . .W1 20

19 W1 . . . . . . . . . . . . . . . . . .W1 19

18 W1 . . . . . . . . . . . . . . . . . .W1 18

17 W1 . . . . . . . . . . . . . . . . . .W1 17

16 W1 . . . . . . . . . . . . . . . . . .W1 16

15 W1 . . . . . . . . . . . . . . . . . .W1 15

14 W1 . . . . . . . . . . . . . . . . . .W1 14

13 W1 . . . . . . . . . . . . . . . . . .W1 13

12 W1 . . . . . . . . . . . . . . . . . .W1 12

11 W1 . . . . . . . . . . . . . . . . . .W1 11

10 W1 . . . . . . . . . . . . . . . . . .W1 10

9 W1 . . . . . . . . . . . . . . . . . .W1 9

8 W1 . . . . . . . . . . . . . . . . . .W1 8

7 W1 . . . . . . . . . . . . . . . . . .W1 7

6 W1 . . . . . . . . . . . . . . . . . .W1 6

5 W1 . . . . . . . . . . . . . . . . . .W1 5

4 W1 . . . . . . . . . . . . . . . . . .W1 4

3 W1 . . . . . . . . . . . . . . . . . .W1 3

2 W1 . . . . . . . . . . . . . . . . . .W1 2

1 W1W1W1W1W2W2W2W2W2W2W2W2W2W2W2W2W1W1W1W1 1

J I= 2 4 6 8 10 12 14 16 18 20



Step 3: Models

1. Activate heat transfer, Eulerian multiphase, and time de-pendence.

De�ne�!Models...

(a) Turn on the Calculate Temperature and Time Depen-dent Flow options, and increase the Time Step to 0.05.

! For problems in which the secondary phase is createddue to mass transfer and no other sources of that phaseexist, you must do one of the following:

� set the time step so that some secondary-phase masswill be created within the �rst time step



� patch a small secondary-phase volume fraction some-where in the computational domain

In this tutorial, a time step of 0.05 is used, and youwill patch a small vapor volume fraction just above theheated portion of the bottom wall (in Step 6).

(b) Under Multiphase, select Eulerian in the Model drop-down list.

(c) Click Apply.

(d) In the Integer Entry dialog box that appears, click OKto allocate memory for one additional phase.

At this point, FLUENT is just setting aside memory for the

additional phase. You will de�ne the phases in a later step.

2. Enable heat and mass transfer calculations for the multi-phase model.

(a) Click on the Multiphase Parameters... button in theModels panel.

(b) In the resulting Multiphase Parameters panel, turn onMass Transfer and Heat-Exchange Coe�cient and turno� Primary Phase Mass Correction.



Note: By default, the uxes of the primary phase at the out-let are corrected by performing a global continuity checkfor extra mass creation or destruction in the domain.Since there is no net out ow of the primary phase goingthrough the outlet boundary in this problem, you need todisable the mass correction for the primary phase (wa-ter).

(c) Click Apply and close the panel.

(d) Close the Models panel.



3. De�ne the primary (water) and secondary (vapor) phases.

SETUP1�!DEFINE-PHASES

(SETUP1)-

DP

(I)- NUMBER OF SECONDARY PHASES

(I)- ++(DEFAULT 1)++

1

(PHASE NAMES)

NOTE : PHASE NAMES CANNOT CONSIST OF

A SINGLE CHARACTER C OR X

WATER PRIMARY PHASE

VAPOR PHASE 2

D ACTION (TOP,DONE,QUIT,REFRESH)

4. De�ne the evaporation submodel.

The mass transfer between the water and vapor phases will be mod-

eled using the two-phase evaporation/condensation submodel. You

can retain the default time relaxation parameters (0.1 for both)

and set the saturation temperature. The evaporation/condensation

submodel will be activated in each cell when the temperature in that

cell exceeds the speci�ed saturation temperature. See the FLUENT

User's Guide for details about these parameters.

SETUP1�! DEFINE-MODELS�! MULTIPLE-PHASES�!

MASS-TRANSFER



(DEFINE-MODELS)-

MP

(MULTIPHASE MODEL (SELECT ONLY ONE))

YES EULERIAN-EULERIAN MULTIPHASE FLOW

NO EULERIAN-EULERIAN GRANULAR FLOW

NO VOF FREE SURFACE


COMMANDS AVAILABLE FROM MULTIPHASE:

DEFINE-PHASES MULTIPHASE-OPTIONS MASS-TRANSFER

QUIT HELP

ENTER HELP (COMMAND) FOR MORE INFORMATION.

(MULTIPHASE)-

MT

(MASS-TRANSFER: SELECT ONE OPTION ONLY)

NO CONSTANT MASS FLOW RATE TRANSFER

YES TWO-PHASE EVAPORATION-CONDENSATION


(MASS-TRANSFER: SELECT ONE OPTION ONLY)

(L)- CALCULATE PARTICULATE DIAMETER?

(L)- Y OR N ++(DEFAULT-NO)++

Y

(EVAPORATION-CONDENSATION COEFFICIENTS)

1.0000E-01 EVAPORATION TIME RELAXATION (/S)

1.0000E-01 CONDENSATION TIME RELAXATION (/S)

373 SATURATION TEMPERATURE (K)




5. Set the gravitational acceleration.

EXPERT�!BODY-FORCES

(EXPERT)-

BF

(BODY FORCES)

YES IMPROVED TREATMENT OF BODY FORCE IN DISCRETE EQNS.

YES INCLUDE BODY FORCE TERMS IN VELOCITY INTERPOLATION

0.0000E+00 GRAVITY ACCELERATION IN X-DIRN - (M/S2)

-9.81 GRAVITY ACCELERATION IN Y-DIRN - (M/S2)

NO USER DEFINED REFERENCE DENSITY


Step 4: Physical Properties

1. Set the density, viscosity, speci�c heat, and thermal conduc-tivity of the water and vapor phases.

SETUP1�!PHYSICAL-CONSTANTS

(SETUP1)-

PC

(PHYSICAL-CONSTANTS)-

DEN



COMMANDS AVAILABLE FROM PHASE-SELECTION:

VAPOR WATER QUIT HELP

ENTER HELP (COMMAND) FOR MORE INFORMATION.

(PHASE-SELECTION)-

WAT

(L)- USE GAS LAW FOR WATER?

(L)- Y OR N ++(DEFAULT-NO)++

N

(*)- DEFINE DENSITY OF WATER (KG/M3)

(*)- AS A FUNCTION OF TEMPERATURE (K)

(*)-

(I)- NUMBER OF COEFFICIENTS (+VE = POLYNOM., -VE = P.W.LINEAR)


1

(R)- DENSITY OF WATER (KG/M3)

(R)- UNITS= KG/M3 ++(DEFAULT 1.0000E+03)++

1000

(R)- NORMALIZING DENSITY FOR WATER


1000

(PHASE-SELECTION)-

VAP

(*)- DEFINE DENSITY OF OF VAPOR (KG/M3)

(*)- AS A FUNCTION OF TEMPERATURE (K)

(*)-

(I)- NUMBER OF COEFFICIENTS (+VE = POLYNOM.,-VE = P.W.LINEAR,-1 = HARMONIC)


1

(R)- DENSITY OF OF VAPOR (KG/M3)


0.5542

(R)- NORMALIZING DENSITY FOR VAPOR


0.5542

(R)- MEAN DIAMETER FOR VAPOR

(R)- UNITS= M ++(DEFAULT 2.0000E-04)++

X

(R)- DEFAULT ASSUMED

(PHASE-SELECTION)-

Q




VIS

(PHASE-SELECTION)-

WAT X 9E-4

(PHASE-SELECTION)-

VAP X 1.34E-5

(PHASE-SELECTION)-

Q


CP

(R)- REFERENCE TEMPERATURE FOR ENTHALPY

(R)- UNITS= K ++(DEFAULT 2.7300E+02)++

273

(PHASE-SELECTION)-

WAT X 4182

(PHASE-SELECTION)-

VAP X 2014 Q


TC

(PHASE-SELECTION)-

WAT X 0.6

(PHASE-SELECTION)-

VAP X 2.61E-2 Q

2. List the physical properties to check them.

SETUP1�!LIST-PHYSICAL-CONSTANTS



(SETUP1)-

LPC

(LIST-PHYSICAL-CONSTANTS)-

DEN

- DENSITY DEFINITION FOR WATER

DENSITY = 1.000E+03

- DENSITY DEFINITION FOR VAPOR

DENSITY = 5.542E-01

PHASE NORMALIZING MEAN

NAME DENSITY DIAMETER

---------- ------------ ------------

WATER 1.000E+03

VAPOR 5.542E-01 2.000E-04


VIS

- VISCOSITY DEFINITION FOR WATER

VISCOSITY = 9.000E-04

- VISCOSITY DEFINITION FOR VAPOR

VISCOSITY = 1.340E-05


CP

- SPECIFIC HEAT DEFINITION FOR WATER

CP = 4.182E+03

- SPECIFIC HEAT DEFINITION FOR VAPOR

CP = 2.014E+03

ENTHALPY REFERENCE TEMPERATURE = 2.7300E+02




TC

- THERMAL CONDUCTIVITY DEFINITION FOR WATER

K = 6.000E-01

- THERMAL CONDUCTIVITY DEFINITION FOR VAPOR

K = 2.610E-02

Step 5: Boundary Conditions

De�ne�!BCs...

1. Specify a zero heat ux condition for W-WALL-1 (the sidewalls and the unheated portion of the bottom surface).



(a) Select Heat Flux as the thermal boundary conditionType and retain the default Heat Flux of 0.




2. Set the temperature for W-WALL-2 (the heated portion ofthe bottom surface).

(a) Enter 573 in the Temperature �eld.


3. Return to the MAIN text menu and save the case �le (boilw.cas).

File�!Write�!Case...



Step 6: Solution

1. Set the underrelaxation parameters.

Solve�! Controls�!Underrelaxation...

(a) Set the Underrelaxation factors to the values shown inthe panel above.

(b) Use the scroll bar at the right of the panel to scrolldown the list of equations, and set the underrelaxationfactor for TEMPERATURE to 0.9.




2. Use the Line Gauss-Seidel solver for all equations, and in-crease the number of solver sweeps.

Solve�! Controls�!Line Gauss...

(a) Turn on the Use Line Gauss button for all equations.

(b) Increase the Number of Sweeps for each equation to thevalues shown in the panel above.


3. Enable the display of residuals during the solution process.

Solve�!Monitor�!Residuals...



Activate the Plot option under Options, and then click onApply and close the panel.

4. Save the case �le (boilw.cas) again with the new solversettings.

File�!Write�!Case...

When prompted, you can con�rm that it is OK to overwrite the

existing case �le.

5. Patch an initial temperature of 370 K throughout the entiredomain, and then a temperature of 372.98 K and a vaporvolume fraction of 0.0001 in the cells just above the heatedportion of the wall.

! As mentioned in Step 3, for problems in which the secondaryphase is created due to mass transfer and no other sourcesof that phase exist, you must ensure that some secondary-phase mass is created within the �rst time step, either bymanipulating the time step, or by patching a small secondary-phase volume fraction in the computational domain. In thistutorial, a vapor volume fraction of 0.0001 is patched justabove the heated portion of the bottom wall.



Patching a temperature of 372.98 K above the heated wall is a good

way to initiate the mass transfer calculation, which will begin at

the saturation temperature of 373 K.

MAIN�!PATCH

(*MAIN*)-

PA X X X X

(VARIABLE-SELECTION)-

TEMP

(PHASE-SELECTION)-

WAT 370


TEMP VAP 370 Q

(*MAIN*)-

PA 5 16 2 2


TEMP WAT 372.98


TEMP VAP 372.98


VF 1E-4 Q

6. Save the initial temperature data to a data �le (boilw0.dat).

File�!Write�!Data...

7. Request 30 time steps.

Solve�!Iterate...



8. Check the solution at t = 1:5 seconds to be sure that thecalculation is proceeding as expected.

(a) Plot velocity vectors for the water and vapor phases.

Display�!Vectors...

i. Using the default settings forWATER, set the ScaleFactor to 7, and click Display.

The water velocity vectors are shown in Figure 20.3.



Some recirculation due to the rising of the vapor bubbles

is visible at the bottom of the tank.

1.07E-04

1.48E-03

2.86E-03

4.24E-03

5.61E-03

6.99E-03

8.36E-03

9.74E-03

1.11E-02

1.25E-02

1.39E-02

1.52E-02

1.66E-02

1.80E-02

1.94E-02

2.07E-02

2.21E-02

2.35E-02

2.49E-02

2.62E-02

2.76E-02

2.90E-02

3.04E-02

3.18E-02

3.31E-02

3.45E-02

3.59E-02

3.73E-02

3.86E-02

4.00E-02

Max = 4.001E-02 Min = 1.073E-04 Time = 1.500E+00Water Velocity Vectors (M/S)Boiling Water

Fluent Inc.Fluent 4.40

Y

XZ

Figure 20.3: Water Velocity Vectors at t = 1:5 sec

ii. Select VAPOR in both Phase drop-down lists andclick on Display.

The vapor velocity vectors are shown in Figure 20.4.

The vapor is beginning to rise, causing some recircula-

tion at the bottom of the tank.



0.00E+00

1.48E-03

2.96E-03

4.43E-03

5.91E-03

7.39E-03

8.87E-03

1.03E-02

1.18E-02

1.33E-02

1.48E-02

1.63E-02

1.77E-02

1.92E-02

2.07E-02

2.22E-02

2.36E-02

2.51E-02

2.66E-02

2.81E-02

2.96E-02

3.10E-02

3.25E-02

3.40E-02

3.55E-02

3.69E-02

3.84E-02

3.99E-02

4.14E-02

4.29E-02

Max = 4.286E-02 Min = 0.000E+00 Time = 1.500E+00Vapor Velocity Vectors (M/S)Boiling Water


Y

XZ

Figure 20.4: Vapor Velocity Vectors at t = 1:5 sec



(b) Plot �lled contours of water volume fraction.

Display�!Contours...

i. Turn on the Filled option and choose Volume Frac-tion (in theMultiphase... category) in the ContoursOf drop-down list.

ii. Retain the default Phase of WATER and click onDisplay.

Figure 20.5 shows the water volume fraction. Vapor is

created near the wall where the temperature is greater

than 373 K.



9.54E-01

9.56E-01

9.57E-01

9.59E-01

9.60E-01

9.62E-01

9.63E-01

9.65E-01

9.66E-01

9.68E-01

9.69E-01

9.71E-01

9.72E-01

9.74E-01

9.75E-01

9.77E-01

9.79E-01

9.80E-01

9.82E-01

9.83E-01

9.85E-01

9.86E-01

9.88E-01

9.89E-01

9.91E-01

9.92E-01

9.94E-01

9.95E-01

9.97E-01

9.98E-01

1.00E+00

Max = 1.000E+00 Min = 9.540E-01 Time = 1.500E+00Water Volume FractionBoiling Water


Y

XZ

Figure 20.5: Water Volume Fraction at t = 1:5 sec



(c) Plot �lled contours of water temperature.


i. Select Temperature in the Contours Of drop-downlist.

ii. Set the Max temperature to 373 and click on Dis-play.

Since the temperature at which water evaporates is 373 K,

you can limit the display of water temperature to tem-

peratures below this value.

3.70E+02

3.70E+02

3.70E+02

3.70E+02

3.70E+02

3.70E+02

3.71E+02

3.71E+02

3.71E+02

3.71E+02

3.71E+02

3.71E+02

3.71E+02

3.71E+02

3.71E+02

3.71E+02

3.72E+02

3.72E+02

3.72E+02

3.72E+02

3.72E+02

3.72E+02

3.72E+02

3.72E+02

3.72E+02

3.72E+02

3.73E+02

3.73E+02

3.73E+02

3.73E+02

3.73E+02

Max = 3.730E+02 Min = 3.700E+02 Time = 1.500E+00Water Temperature (K)Boiling Water


Y

XZ

Figure 20.6: Water Temperature at t = 1:5 sec

Figure 20.6 shows that the water temperature is highest

near the heated portion of the wall, just above where

the vapor has been created. (The blank region at the

bottom of the contour plot indicates that the temperature

in this location is out of the plotted temperature range,

i.e., greater than 373 K.)



Since the calculation is proceeding well, you will continue the sim-

ulation for a total of 300 time steps, using the automatic data

saving feature to save the data at 100, 200, and 300 time steps.

9. Request the automatic saving of data �les.

De�ne�!Models...

(a) In the Models panel, click on the Time Parameters...button.

(b) In the resulting Time Dependent Flow Parameters panel,turn on the Auto Save Data Files option and set thenumber of Time Steps Between Saves to 100.

(c) Click Apply, close the panel, and close theModels panel.

10. Request 270 time steps.

Solve�!Iterate...

Enter the name "boilw" for the auto-save data �le pre�x,when prompted.



(*)- FLUID PHASE CALCULATION

(*)- AUTO-SAVE DATA FILES ARE LABELED AS:

(*)- (USER SUPPLIED PREFIX)(TIME STEP)

ENTER AUTO-SAVE FILE PREFIX (ENTER * TO CANCEL)

(S)- DEFAULT- NTIME

"boilw"

Step 7: Postprocessing

When the 300 time steps are completed, you will have three data �les,

boilw100, boilw200, and boilw300, corresponding to t = 5, 10, and 15

seconds, respectively. You can read each data �le and examine velocities

and volume fraction as you did at t = 1:5 in Step 6.

1. Plot velocity vectors for the water and vapor phases and thewater volume fraction at t = 5 seconds.

(a) Read the t = 5 data from boilw100.

File�! Read�!Data...

(b) Plot the water and vapor velocity vectors (Figures 20.7and 20.8).

Display�!Vectors...

i. ChooseWATER in both Phase drop-down lists andclick on Display.

ii. Choose VAPOR in both Phase drop-down lists andclick on Display.

In Figures 20.7 and 20.8 you can see that the recirculation

pattern has become elongated, as the vapor bubbles continue

to rise further up the column.



1.16E-07

3.46E-03

6.92E-03

1.04E-02

1.38E-02

1.73E-02

2.08E-02

2.42E-02

2.77E-02

3.12E-02

3.46E-02

3.81E-02

4.15E-02

4.50E-02

4.85E-02

5.19E-02

5.54E-02

5.88E-02

6.23E-02

6.58E-02

6.92E-02

7.27E-02

7.61E-02

7.96E-02

8.31E-02

8.65E-02

9.00E-02

9.35E-02

9.69E-02

1.00E-01



Y

XZ

Figure 20.7: Water Velocity Vectors at t = 5 sec

0.00E+00

3.51E-03

7.02E-03

1.05E-02

1.40E-02

1.76E-02

2.11E-02

2.46E-02

2.81E-02

3.16E-02

3.51E-02

3.86E-02

4.21E-02

4.57E-02

4.92E-02

5.27E-02

5.62E-02

5.97E-02

6.32E-02

6.67E-02

7.02E-02

7.38E-02

7.73E-02

8.08E-02

8.43E-02

8.78E-02

9.13E-02

9.48E-02

9.83E-02

1.02E-01



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Figure 20.8: Vapor Velocity Vectors at t = 5 sec



(c) Plot �lled contours of water volume fraction.


i. Retain the Filled option and choose Volume Frac-tion (in theMultiphase... category) in the ContoursOf drop-down list.

ii. Retain the default Phase of WATER and click onDisplay.

Figure 20.9 shows that the vapor front has risen up the

column.

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Figure 20.9: Water Volume Fraction at t = 5 sec

(d) Plot �lled contours of water temperature.


i. Select Temperature in the Contours Of drop-downlist.



ii. Set the Max temperature to 373 and click on Dis-play.

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Figure 20.10: Water Temperature at t = 5 sec

Figure 20.10 shows that as the vapor front rises, the

vapor is heating the surrounding water.

2. Plot velocity vectors for the water and vapor phases and thewater volume fraction and temperature at t = 10 seconds.



(b) Follow the steps above for the t = 5 solution to plotthe velocity vectors and volume fraction.

Hint: When you plot the temperature contours, remember toset the Max temperature to 373.



2.89E-07

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0.00E+00

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Figures 20.11{20.14 show the changes in the recirculation

pattern due to the height of the vapor bubbles and the di�er-

ence in temperature between the side walls and the center of

the column.

3. Plot velocity vectors for the water and vapor phases and thewater volume fraction and temperature at t = 15 seconds.



(b) Follow the steps above for the t = 5 solution to plotthe velocity vectors and volume fraction.

Hint: When you plot the temperature contours, remember toset the Max temperature to 373.

Figures 20.15{20.18 show further changes in the recircula-

tion pattern as the vapor rises up the column.



7.11E-07

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Summary: In this tutorial, you have learned how to use the mul-tiphase mass transfer submodel for evaporation/condensation tosolve a problem involving boiling water in a container. Data �leswere saved automatically at 5 second intervals during the transientcalculation, and postprocessing of each data set showed the for-mation of the vapor bubbles due to convection from a heated wall,their subsequent rise through the water column due to buoyancy,and the resulting recirculation patterns.


Documents

Boiling of Water