# Evaporation due to Heat Transport using InterFoam (Correct Implementation?)

 Register Blogs Members List Search Today's Posts Mark Forums Read

 October 3, 2010, 04:10 Evaporation due to Heat Transport using InterFoam (Correct Implementation?) #1 Member   Ovie Doro Join Date: Jul 2009 Posts: 99 Rep Power: 8 Hi, I have tried to implement phase change due to evaporation for an incompressible liquid flowing down a vertical heated wall using interFOAM with an energy transport equation. I have employed the methods suggested by Bitan Shu (Phase Change Model for Two-Phase Fluid Flow Based on VOF Method) and Wondra et al. (Evaporation Model for Interfacial Flows Based on a Continuum Field Representation of the Source Terms). However in both cases, I am unable to accurately reproduce the results presented in their papers. I am particularly interested in Bitan Shu's implementation because it allows for large grid sizes. Has anyone successfully done this? If anyone has, please take a look at my code and tell me where I am wrong. Help is needed PLEASE! STEP 1: Solve the energy transport equation for the entire domain i.e. (both liquid and gas): STEP 2: Compute source terms using gradient of temperature: Code: ``` volVectorField gradAlpha = fvc::grad(alpha1); // to compute interface normal unit vector volVectorField nHat = gradAlpha/(mag(gradAlpha) + interface.deltaN()); // compute interfacial area = magnitude of grad(alpha1)*volume of cell volScalarField alpha1Prime = mag(gradAlpha); // set liquid and interfacial temperature to Tsat forAll(mesh.cells(), celli) { if (alpha1[celli] >= scalar(0.5)) { T[celli] = Tsat.value(); } // set this values to zero so that only liquid evaporation is accounted for if (alpha1[celli] < scalar(0.50)) { alpha1Prime[celli] = scalar(0); } } // Compute mass source field mDot = -(kappa/evapEnthalpy)*(fvc::grad(T) & nHat)*alpha1Prime; // Compute energy source field using enthalpy of evaporation hDot = -evapEnthalpy*mDot;``` kappa = thermal conductivity evapEnthalpy = heat of vaporization rho1 = liquid density STEP 3: Solve alpha1 equation using MULES with source terms prescribed as Code: ```Su = -mDot/rho2; Sp = 0.0;``` STEP 4: Call Velocity and PISO loop STEP 5: Repeat STEP 1 Please kindly review and tell me where this is wrong. Suggestions on more correct implementation of the source terms for evaporation would be well appreciated. Thanks for the help. Kanarya likes this.

October 4, 2010, 02:21
#2
Member

Sabin Ceuca
Join Date: Mar 2010
Location: Munich
Posts: 42
Rep Power: 7
Hi Ovie,
I am also struggling to implement temperature driven phase change. I tried the same as you did but my Su=mDot/rhoLiquid=HTC_liquid/rhoLiquid*(Tsat-T)/(latentHeat)*InterfacialAreaDensity. My Source term looks different because my phase change is due to condensation. My problems are that it crashes and I don’t get any reasonable results.
What do you mean by ?
Quote:
 Originally Posted by ovie However in both cases, I am unable to accurately reproduce the results presented in their papers.
Ciao,
Sabin

October 4, 2010, 02:44
#3
Member

Ovie Doro
Join Date: Jul 2009
Posts: 99
Rep Power: 8
Hi Sabin,

Quote:
 However in both cases, I am unable to accurately reproduce the results presented in their papers.
What I meant was that I successfully implemented the model proposed by Wondra et al. in the paper I referenced in the earlier post. I can send you the paper and my implementation if you want. I ran the code and it was well behaved and I had nice results. The only problem was that it under predicted the phase change compared to the results they reported in their paper. But the under-prediction was not by much though (really small but then the simulation was for micro scale and I fear this underprediction could be significant at macro scale). In any case, I SUSPECT the problem was with my boundary conditions because in their case they simulated 1-D stefan problems while I was unable to do that using interFoam so I used a 2-D mesh with zero gradient and no-slip conditions at planes normal to the transverse directions.

In the case of Bitan Shu's model, the simulation reports completely strange results. I really dont know where to start from at the moment. I am reading up another paper by P. Keller et al. (Numerical Simulation of Evaporating Droplets with Chemical Reactions using a Volume of FLuid Method) where they used interFoam and reported nice results. I think I might get some practical details on the implementation from there.

Thanks..

 October 4, 2010, 03:29 #4 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 11 As far as I know Shu used OpenFOAM in his Ph.D. thesis. I'm sure you can get more informations out of if that of the paper. Try to get it! __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

October 4, 2010, 16:21
#5
Member

Ovie Doro
Join Date: Jul 2009
Posts: 99
Rep Power: 8
Hi Sega

Quote:
 As far as I know Shu used OpenFOAM in his Ph.D. thesis. I'm sure you can get more informations out of if that of the paper. Try to get it!
I already have the conference paper where Shu developed his model. I think my problem is with the implementation right now. If you have any additional materials please be kind to make it available.

Thanks

October 4, 2010, 17:35
#6
Senior Member

Sebastian Gatzka
Join Date: Mar 2009
Location: Frankfurt, Germany
Posts: 729
Rep Power: 11
Quote:
 Originally Posted by ovie Hi Sega I already have the conference paper where Shu developed his model. I think my problem is with the implementation right now. If you have any additional materials please be kind to make it available. Thanks
I have the Ph.D. thesis at hand, but I'm not sure Bitan Shu will be happy if I publish it here.
__________________
Schrödingers wife: "What did you do to the cat? It's half dead!"

October 4, 2010, 17:40
#7
Member

Ovie Doro
Join Date: Jul 2009
Posts: 99
Rep Power: 8
Quote:
 I have the Ph.D. thesis at hand, but I'm not sure Bitan Shu will be happy if I publish it here.
Actually, I have been in direct communication with Bitan Shu. But he/she told me his/her Thesis was in German and offered to send me a copy but I passed since I dont have a clue about German language. Maybe I got it wrong. I can send him a mail and ask again if he/she has an English version or something. But do you have an English version of the thesis?

Thanks...

October 4, 2010, 17:46
#8
Senior Member

Sebastian Gatzka
Join Date: Mar 2009
Location: Frankfurt, Germany
Posts: 729
Rep Power: 11
Quote:
 Originally Posted by ovie Actually, I have been in direct communication with Bitan Shu. But he/she told me his/her Thesis was in German and offered to send me a copy but I passed since I dont have a clue about German language. Maybe I got it wrong. I can send him a mail and ask again if he/she has an English version or something. But do you have an English version of the thesis? Thanks...
No, I just have the german version ...
__________________
Schrödingers wife: "What did you do to the cat? It's half dead!"

 October 4, 2010, 17:48 #9 Member   Ovie Doro Join Date: Jul 2009 Posts: 99 Rep Power: 8 Very well then. Thanks for the help.

 October 6, 2010, 04:54 #10 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,147 Blog Entries: 1 Rep Power: 15 hi ovie could you implement shu paper properly ? i tried it, i have used interPhaseChangeFoam , but my results can't follow interface exactly,please inform me about ur last effort!!!!! and i suggest you look at interPhaseChangeFoam and MULE code in it !!!!

 December 16, 2011, 08:02 #11 Member   Lars Kiewidt Join Date: Sep 2009 Location: Germany Posts: 54 Rep Power: 8 Ovie, by the way, I found that my results depend on the timestep. The larger the timestep, the more liquid is evaporating.

December 16, 2011, 08:10
#12
Member

Ovie Doro
Join Date: Jul 2009
Posts: 99
Rep Power: 8
Quote:
 Originally Posted by LarsPT Ovie, by the way, I found that my results depend on the timestep. The larger the timestep, the more liquid is evaporating.
Well that comes down to your grid sizes and the size of your CFL number. In my case I used a well resolved grid (try the grid sizes specified in Wondra's paper) and specified variable time step in controlDict. The results were very comparable to those reported in Wondra's paper.

December 16, 2011, 10:44
#13
Senior Member

Nima Samkhaniani
Join Date: Sep 2009
Location: Tehran, Iran
Posts: 1,147
Blog Entries: 1
Rep Power: 15
Quote:
 Originally Posted by LarsPT Ovie, by the way, I found that my results depend on the timestep. The larger the timestep, the more liquid is evaporating.
look at here
http://www.cfd-online.com/Forums/blogs/nimasam/906-boiling-openfoam.html

and here
evapPhaseChangeFOAM

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Flo.duck Main CFD Forum 0 May 6, 2009 03:37 Anbazhagan R Fluent UDF and Scheme Programming 2 May 3, 2009 07:43 B.Simon CFX 3 October 28, 2008 19:53 yves OpenFOAM Running, Solving & CFD 1 May 5, 2006 05:33 Sascha Becker CFX 2 December 20, 1999 03:58

All times are GMT -4. The time now is 10:56.