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Bubble is not increasing in size in Nucleate boiling |
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September 2, 2019, 18:34 |
Bubble is not increasing in size in Nucleate boiling
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#1 |
Member
FaRa
Join Date: Jul 2019
Posts: 33
Rep Power: 7 |
Hello everyone,
I am running my simulation on Nucleate Boiling. My bubble has been created successfully like a semi-sphere on a heated surface but for some reason it is not increasing its size. What can be the reason behind this? Any idea would be appreciated. Thank you. |
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September 12, 2019, 18:43 |
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#2 |
Senior Member
sandy
Join Date: Feb 2016
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Posts: 117
Rep Power: 10 |
what solver are you using ?
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September 17, 2019, 02:37 |
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#3 | |
New Member
Bali
Join Date: Oct 2018
Posts: 14
Rep Power: 8 |
Quote:
could you upload your case files so that we can see where the problem is |
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September 17, 2019, 16:12 |
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#4 |
Member
FaRa
Join Date: Jul 2019
Posts: 33
Rep Power: 7 |
hi Saddy,
Thank you for your response. I am using interThermalPhaseChangeFoam solver which has been extended from interFoam. Here is the paper link: https://www.sciencedirect.com/scienc...52711016300309 |
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September 17, 2019, 16:48 |
Case files
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#5 |
Member
FaRa
Join Date: Jul 2019
Posts: 33
Rep Power: 7 |
Hi Bali, thank you for your response.
Here is my blockMesh file: Code:
convertToMeters 1; vertices ( (0 0 0) (0.031 0 0) (0.031 0.031 0) (0 0.031 0) (0 0 0.031) (0.031 0 0.031) (0.031 0.031 0.031) (0 0.031 0.031) ); blocks ( hex (0 1 2 3 4 5 6 7) (120 120 120) simpleGrading (1 1 1) ); edges ( ); boundary ( bottom { type wall; faces ( (1 5 4 0) ); } outlet { type patch; faces ( (3 7 6 2) ); } walls { type wall; faces ( (0 4 7 3) (2 6 5 1) (0 1 2 3) (4 5 6 7) ); } ); mergePatchPairs ( ); Code:
actions ( { name c0; type cellSet; action new; source sphereToCell; sourceInfo { centre (0.0155 0 0.0155); radius 0.001; } } { name c0; type cellSet; action delete; source boxToCell; sourceInfo { box (0.0145 -0.001 0.0145) (0.0165 0 0.0165); } } ); Code:
defaultFieldValues ( volScalarFieldValue alpha1 0 volScalarFieldValue T 559.95 volVectorFieldValue U (0 0 0) ); regions ( boxToCell { box (0 0 0) (0.031 0.026 0.031); fieldValues ( volScalarFieldValue alpha1 1 volScalarFieldValue T 559.95 volVectorFieldValue U (0 0 0) ); } cellToCell { set c0; fieldValues ( volScalarFieldValue alpha1 0 volScalarFieldValue T 559.95 volVectorFieldValue U (0 0 0) ); } ); ParaView file is also attached. Here, I would like to mention that I was able to grow the bubble size when performing in 2D with meshes of 150x150. For 3D, I have tried several meshes upto 120x120x120 with different values of Evaporation threshold number but the bubble size did not increase. I think the mesh of 150x150x150 may solve the issue. But since I am performing my simulation on my laptop with only 6 cores parallel processing, it is not possible for me to turn my pc on for a week. So any alternate suggestion is needed. |
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November 17, 2019, 05:26 |
Bubble detachment diameter
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#6 |
Member
FaRa
Join Date: Jul 2019
Posts: 33
Rep Power: 7 |
Hello everyone, I came out successfully in growing my bubble .
Now I have got the bubble detachment time by watching it in paraview. But I also need to calculate the detachment diameter in controlDict. Does anyone have any idea how to do this? |
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November 17, 2019, 13:07 |
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#7 |
Member
FaRa
Join Date: Jul 2019
Posts: 33
Rep Power: 7 |
I have been able to calculate the vapor surface area for each timestep using swak4foam. But this is including the vapor over the liquid surface . Is there any way to remove them?
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November 17, 2019, 13:33 |
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#8 |
Member
Sam
Join Date: May 2019
Posts: 64
Rep Power: 7 |
Hi Fahmida,
I am also using the interThermalPhaseChangeFoam framework for modelling bubble sliding. I was curious what boundary conditions for the p-rgh field you have been using for your simulations. Kind regards, Sam |
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November 17, 2019, 14:07 |
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#9 |
Member
FaRa
Join Date: Jul 2019
Posts: 33
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Hello,
In my computational domain consisting air and liquid has a fixedFluxPressure boundary condition for the inlet and side walls and a total pressure with p0 0 for the outflow. |
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November 19, 2019, 20:07 |
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#10 |
Member
Sam
Join Date: May 2019
Posts: 64
Rep Power: 7 |
Thanks,
Did you find out why the bubble size did not increase in your simulation? |
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November 20, 2019, 06:01 |
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#11 |
Member
FaRa
Join Date: Jul 2019
Posts: 33
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I had to reduce the domain size and increase the evaporation threshold number although I am not clear enough how the evaporation number was effecting this issue.
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December 3, 2019, 23:41 |
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#12 |
Member
Sam
Join Date: May 2019
Posts: 64
Rep Power: 7 |
Thank you for the help.
How did you initialise the perfect bubble shape especially on a perfectly smooth surface. Sorry for asking, I'm not very good at OpenFoam |
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December 4, 2019, 00:10 |
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#13 | |
New Member
Bali
Join Date: Oct 2018
Posts: 14
Rep Power: 8 |
Quote:
BTW, the solver evapVOFHardt based on of231 is also useful for bubble growth simulation. It should be noted that spurious current might be an issue in this kind of simulation |
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December 4, 2019, 01:15 |
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#14 |
Member
Sam
Join Date: May 2019
Posts: 64
Rep Power: 7 |
Hi,
Thanks, yeah there is but the simulation relies on a cavity in the mesh rather than a smooth surface. Btw have you had any issues changing boundary conditions of the thermalphasechangefoam solver. When I have the simulation has quickly collapsed. For example for a vapour surrrounded in a superheated liquid scenario. I can provide for detail if required. Thanks again. |
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December 4, 2019, 01:22 |
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#15 | |
New Member
Bali
Join Date: Oct 2018
Posts: 14
Rep Power: 8 |
Quote:
it will be good to check your case if can upload it. Best |
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December 8, 2019, 00:03 |
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#16 |
Member
Sam
Join Date: May 2019
Posts: 64
Rep Power: 7 |
Hi Bali,
Sorry, for the late reply. This is the common error, I repeatedly get. I assume it is an issue of my pressure boundaries. If you understand why, could you explain to me as simply as possible . --> FOAM FATAL IO ERROR: wrong token type - expected Scalar, found on line 0 the word 'nan' file: /home/joseph/OpenFOAM/joseph-2.4.0/run/CFD-PC-master/CFD-PC/interThermalPhaseFoam/tutorials/VapourGrowthWithoutLayer/system/data.solverPerformance.p_rgh at line 0. From function operator>>(Istream&, Scalar&) in file lnInclude/Scalar.C at line 93. Thank you for the help. Sam |
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December 8, 2019, 00:33 |
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#17 | |
New Member
Bali
Join Date: Oct 2018
Posts: 14
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Quote:
hi Sam, I have checked your files. Here some points: 1. why the "base" boundary is applied with "symmetry"? if it is a base wall boundary, "symmetry" is not appropriate. 2. I guess you can not use "fixedvalue 0" for "top" and "right" boundary at the same time. one of them could be changed into "zeroGradient" |
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December 8, 2019, 00:39 |
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#18 |
Member
Sam
Join Date: May 2019
Posts: 64
Rep Power: 7 |
Sorry for the confusion, the base in this case is symmetry because the bubble is initialised in the simulation so that it is a 1/4 of a bubble. So that the computing requirement can be reduced.
Okay I will try that and come back to you if it works. Thanks again. |
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December 8, 2019, 00:40 |
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#19 |
New Member
Bali
Join Date: Oct 2018
Posts: 14
Rep Power: 8 |
OK. but I guess "symmetryPlane" might be better
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December 8, 2019, 22:47 |
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#20 |
Member
Sam
Join Date: May 2019
Posts: 64
Rep Power: 7 |
Sad news, your suggestions didn't work. The symmetryPlane BC on the base affects the axisymmetric setup and prevents it running. Do you have any other suggestions ?
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bubble, nucleate boiling |
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