CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Heat conduction problems in OF220

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 20, 2013, 04:47
Default Heat conduction problems in OF220
  #1
New Member
 
Join Date: Apr 2011
Location: Magdeburg, Germany
Posts: 23
Rep Power: 14
Nico A. is on a distinguished road
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
File Type: jpg flange.jpg (20.0 KB, 58 views)
Nico A. is offline   Reply With Quote

Old   March 20, 2013, 05:35
Default
  #2
New Member
 
Join Date: Apr 2011
Location: Magdeburg, Germany
Posts: 23
Rep Power: 14
Nico A. is on a distinguished road
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<fvScalarMatrix> 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<fvScalarMatrix> 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
Nico A. is offline   Reply With Quote

Old   June 15, 2013, 08:37
Default
  #3
New Member
 
ali
Join Date: Aug 2012
Posts: 5
Rep Power: 13
abigail158 is on a distinguished road
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!
abigail158 is offline   Reply With Quote

Old   September 4, 2013, 14:38
Default
  #4
Member
 
X Meng
Join Date: Jun 2012
Location: Scotland
Posts: 89
Rep Power: 13
mxylondon is on a distinguished road
I am working on this issue as well. They should be the same things, but still don't understand what 'betav' is.
mxylondon is offline   Reply With Quote

Old   March 12, 2014, 13:10
Default
  #5
Member
 
Vitor Vasconcelos
Join Date: Jan 2012
Posts: 33
Rep Power: 14
vitors is on a distinguished road
I'm also interested in understanding betav and fvOptions(rho, h).

Waiting for the enlightenment...
vitors is offline   Reply With Quote

Old   March 14, 2014, 07:07
Default
  #6
New Member
 
akrasemann
Join Date: Dec 2013
Posts: 17
Rep Power: 12
akrasemann is on a distinguished road
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.
akrasemann is offline   Reply With Quote

Old   March 14, 2014, 10:21
Default
  #7
Member
 
Vitor Vasconcelos
Join Date: Jan 2012
Posts: 33
Rep Power: 14
vitors is on a distinguished road
Quote:
Originally Posted by akrasemann View Post
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!
vitors is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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 Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Heat transfer problems nagarajan FLUENT 2 January 13, 2013 11:31
Phase Change Heat Conduction hawkeye321 OpenFOAM 14 April 30, 2011 15:24
heat conduction boundary conditions sivaraja FLUENT 1 June 13, 2009 05:40
heat conduction with temperature profile BC's Arnout FLUENT 1 April 14, 2006 09:30
Conduction heat not balanced? Nepal CFX 7 May 31, 2005 12:51


All times are GMT -4. The time now is 21:11.