# Heat conduction problems in OF220

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

March 20, 2013, 04:47
Heat conduction problems in OF220
#1
New Member

Join Date: Apr 2011
Location: Magdeburg, Germany
Posts: 23
Rep Power: 7
Hello FOAMers,

I actually want to simulate a cht problem with many different regions in OpenFOAM 2.2.0. But when I simulated a little test case, there occur differences in heat conduction from OF 2.1.1 to 2.2.0. You can therefore have a look at the attached picture.

I took the flange case out of the laplacianFoam tutorial. Then I adjusted the material properties for cp, rho and kappa in this way that I should get the same results for laplacianFoam solver and chtMultiRefionFoam solver. (In laplacianFoam we have just DT, which can be calculated as: DT = kappa/(cp*rho) )

The results for laplacianFoam and cht - OF211 simulation are similar. Unfortunately the cht - OF220 simulation differs from that.

So my question is, does anyone know what the problem is in this case? Is it maybe a bug of the new version?

Best regards, Nico
Attached Images
 flange.jpg (20.0 KB, 54 views)

 March 20, 2013, 05:35 #2 New Member   Join Date: Apr 2011 Location: Magdeburg, Germany Posts: 23 Rep Power: 7 I also looked at the source code of solveSolid.H in the cht solver. The TEqn for OF211 is: Code: ```for (int nonOrth=0; nonOrth<=nNonOrthCorr; nonOrth++) { tmp TEqn ( fvm::ddt(rho*cp, T) - fvm::laplacian(kappa, T) ); TEqn().relax(); TEqn().solve(mesh.solver(T.select(finalIter))); }``` For the hEqn in OF220: Code: ```for (int nonOrth=0; nonOrth<=nNonOrthCorr; nonOrth++) { tmp hEqn ( fvm::ddt(betav*rho, h) - fvm::laplacian(betav*alpha, h, "laplacian(alpha,h)") == fvOptions(rho, h) ); hEqn().relax(); fvOptions.constrain(hEqn()); hEqn().solve(mesh.solver(h.select(finalIter))); fvOptions.correct(h); }``` So in the new version there is an additional fvOptions term which I do not use. And enthalpie h is used instead of temperature T. I just don't understand what betav is supposed to mean. Can someone exlain this value? Once more, best regards, Nico

 June 15, 2013, 07:37 #3 New Member   ali Join Date: Aug 2012 Posts: 5 Rep Power: 6 Hi Nico A, i'm also interested in solving multiregion heat transfer and currently testing the solver chtMultiRegionFoam. Have you figured out what 'betav' in createSolidFields.H means? Thx!

 September 4, 2013, 13:38 #4 Member   Xiangyin Meng Join Date: Jun 2012 Location: London Posts: 70 Rep Power: 6 I am working on this issue as well. They should be the same things, but still don't understand what 'betav' is.

 March 12, 2014, 13:10 #5 Member   Vitor Vasconcelos Join Date: Jan 2012 Posts: 33 Rep Power: 6 I'm also interested in understanding betav and fvOptions(rho, h). Waiting for the enlightenment...

 March 14, 2014, 07:07 #6 New Member   akrasemann Join Date: Dec 2013 Posts: 17 Rep Power: 4 fvOptions is a utility enabling you to introduce additional terms into the solver, as far as I understand the release notes http://www.openfoam.org/version2.2.0/fvOptions.php. Regarding the solid region within chtMultiRegionFoam I'm as well curious about the exact meaning of betav. In German textbooks on (solid body-) mechanics the thermal volumetric expansion coefficient is sometimes called beta_v, but I do not understand, why this coefficient should be introduced into the solver.

March 14, 2014, 10:21
#7
Member

Vitor Vasconcelos
Join Date: Jan 2012
Posts: 33
Rep Power: 6
Quote:
 Originally Posted by akrasemann fvOptions is a utility enabling you to introduce additional terms into the solver, as far as I understand the release notes http://www.openfoam.org/version2.2.0/fvOptions.php. Regarding the solid region within chtMultiRegionFoam I'm as well curious about the exact meaning of betav. In German textbooks on (solid body-) mechanics the thermal volumetric expansion coefficient is sometimes called beta_v, but I do not understand, why this coefficient should be introduced into the solver.
Thanks akrasemann,

Actually, I just removed fvOptions(rho, h) from my solver and added a source-term manually. However, I'm still curious on how it works internally. I could check it manupulates a list of pointers to contents in the fvOptions file, but sometimes I have to hold the impetus of try to understand everything in OpenFOAM and just do what I need.

Thanks a lot for your help. I'll do the homework researching on "thermal volumetric expansion coefficient" (at this point you probably realized I'm not an engineer) but please, keep us updated if you get more information about the betav in the solver.

Thank you!

 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 nagarajan FLUENT 2 January 13, 2013 11:31 hawkeye321 OpenFOAM 14 April 30, 2011 14:24 sivaraja FLUENT 1 June 13, 2009 04:40 Arnout FLUENT 1 April 14, 2006 08:30 Nepal CFX 7 May 31, 2005 11:51

All times are GMT -4. The time now is 06:14.

 Contact Us - CFD Online - Top