# simpleFoam with energy equation

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 October 13, 2009, 12:49 simpleFoam with energy equation #1 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 13 Hello world. I'm dealing with a case in which Navier-Stokes and energy equation can be solved one after the other. I have little experience in manipulating solvers, but I think it's possible to alter the simpleFoam solver for such a case. So where do I put the energy equation? As I want to compute temperature after successfully converged Navier-Stokes-Equation I have thought about opening another time-loop and solving the energy equation there. Something like this: Code: ``` Info<< "\nStarting time loop\n" << endl; for (runTime++; !runTime.end(); runTime++) { Info<< "Time = " << runTime.timeName() << nl << endl; # include "readSIMPLEControls.H" # include "initConvergenceCheck.H" p.storePrevIter(); // Pressure-velocity SIMPLE corrector { # include "UEqn.H" # include "pEqn.H" } turbulence->correct(); runTime.write(); Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s" << " ClockTime = " << runTime.elapsedClockTime() << " s" << nl << endl; # include "convergenceCheck.H" } #include 'TEqn.H' Info<< "End\n" << endl; return(0);``` TEqn.H will contain the energy equation. So much for the basics of this problem. Thanks for your ideas. See you. Sebastian __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 October 14, 2009, 02:57 #2 Senior Member   Markus Rehm Join Date: Mar 2009 Location: Erlangen (Germany) Posts: 182 Rep Power: 10 Hi Sebastian, have a look at buoyantSimpleFoam. Regards, Markus.

October 19, 2009, 14:04
#3
Senior Member

Sebastian Gatzka
Join Date: Mar 2009
Location: Frankfurt, Germany
Posts: 729
Rep Power: 13
Quote:
 Originally Posted by markusrehm Hi Sebastian, have a look at buoyantSimpleFoam. Regards, Markus.
I did and it looks to me that the enthalpy equation is solved inside the brackets with U and p.

So I will put the energy equation inside it too?

Code:
```    {
#           include "UEqn.H"
#           include "pEqn.H"
#           include "TEqn.H"
}```
Just to make sure...
__________________
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 November 20, 2009, 15:21 #4 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 13 It took some time before I got back to this construction site: Do you think buoyantSimpleFoam for itself (without chaning anything) will be the right choice for a simple convective heat transfer problem? __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 November 23, 2009, 03:31 #5 Senior Member   Markus Rehm Join Date: Mar 2009 Location: Erlangen (Germany) Posts: 182 Rep Power: 10 It worked well for me. But you can take out the buoyancy term as well. Markus

 January 25, 2013, 16:05 TEqn.H #6 Member   Suranga Dharmarathne Join Date: Jan 2011 Location: TX, USA Posts: 39 Rep Power: 8 Hi Markus and Sebastian, Why can't we put the TEqn.H out side the SIMPLE loop. I think we need to calculate temperature field after we got corrected velocity field. Is my idea right or wrong? And since simpleFoam calculates turbulent flows I put my Teqn.H as, { volScalarField kappaEff ( "kappaEff", turbulence->nu()/Pr + turbulence->nut()/Prt ); fvScalarMatrix TEqn ( //fvm::ddt(T) fvm::div(phi, T) - fvm::laplacian(kappaEff, T) ); TEqn.relax(); TEqn.solve(); //rhok = 1.0 - beta*(T - TRef); } Please correct me if I am wrong. My temperature value fluctuates a lot whenever I used it out side the SIMPLE loop. But in pisoFoam I put it in outside the PISO loop and worked really good. Please advice me. Best regards, Suranga.

 January 26, 2013, 07:42 #7 Senior Member     Hisham Elsafti Join Date: Apr 2011 Location: Braunschweig, Germany Posts: 252 Blog Entries: 10 Rep Power: 10 Hi Suranga I think the (rather old) discussion here was about the time loop not the Simple/pimple loop. Naturally one needs to keep the algorithm for the Navier-Stokes equations intact. You can add whatever equation outside the algorithm to let it resole the pressure-velocity coupling in peace. Of course all equations should be inside the time loop unless you need to solve an equation once. Hisham

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