Darcy solver with boussinesq assumption. Solver crashes for zero gradient BC for Temp
Hello All
I am trying to solver Darcy flow equation with boussinesq assumption. I simulate bottom heated top cooled 2D cavit with adiabatic sidewalls. The solver gives unphysical unbounded Temperature, when I give zeroGradient BC for T (adiabatic). However it doesnt crash when instead of adiabatic I give a fixed temperature value for the side walls as well(fixedValue BC).
Solver details below:
Code:
/*---------------------------------------------------------------------------*\
========= |
\\ / F ield | foam-extend: Open Source CFD
\\ / O peration | Version: 4.0
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Application
laplacianFoam
Description
Solves a simple Laplace equation, e.g. for thermal diffusion in a solid.
\*---------------------------------------------------------------------------*/
#include "fvCFD.H"
#include "singlePhaseTransportModel.H"
#include "simpleControl.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
int main(int argc, char *argv[])
{
# include "setRootCase.H"
# include "createTime.H"
# include "createMesh.H"
simpleControl simple(mesh);
# include "readGravitationalAcceleration.H"
# include "createFields.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Info<< "\nCalculating flow and temperature distribution\n" << endl;
while (simple.loop())
{
Info<< "Time = " << runTime.timeName() << nl << endl;
#include "pEqn.H"
#include "TEqn.H"
# include "write.H"
Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s"
<< " ClockTime = " << runTime.elapsedClockTime() << " s"
<< nl << endl;
}
Info<< "End\n" << endl;
return 0;
}
// ************************************************************************* //
pEqn.H
Code:
{
//phi = fvc::interpolate(U) & mesh.Sf();
surfaceScalarField phiG(Mf*fvc::interpolate(rhok)*(g & mesh.Sf()));
//Test
// surfaceScalarField phiG(Mf*ghf*fvc::snGrad(rhok)*mesh.magSf());
// phi += phiG;
// while (simple.correctNonOrthogonal())
// {
fvScalarMatrix pEqn
(
//fvm::laplacian(-Mf,p) + fvc::div((fvc::interpolate(rhok) * Mf)* (g & mesh.Sf()))
fvm::laplacian(-Mf,p)+ fvc::div(phiG)
);
// pEqn.relax();
pEqn.setReference(pRefCell, pRefValue);
pEqn.solve();
// phi= (phiG + fvc::snGrad(p)*Mf*mesh.magSf());
// if (simple.finalNonOrthogonalIter())
// {
//
phi= (phiG+pEqn.flux());
// p.relax();
//Reconstruct the velocity field.
//Velocity isnt involved in any calculation
//multiplied by fluid density to convert to velocity
//If needed the BC can be set using DarcyPressure BC , where velcoity is converted to pressure
U=fvc::reconstruct
( phi );
// U = fvc::reconstruct(phi);
U.correctBoundaryConditions();
// }
}
TEqn.H
Code:
{
//Solve 1 temperature equation for combined solid and fluid phase
fvScalarMatrix TEqn
(
fvm::laplacian(DT, T)==
(eps*rhoCpf+(1.-eps)*rhoCps)*fvm::ddt(T)
+ rhoCpf*fvm::div(phi,T)
);
// TEqn.relax();
TEqn.solve();
//Density updation based on temperature p/rho is used in implementation
//rhok thus doesnt have unit of density but dimensionless
rhok=rhof*(1.0 - (beta*(T - TRef)));
//solve pressure Eqn. Mf account for K/mu.
//PhiG in createfields takes care of density induced flux
}
Could someone help me to find why zeroGradient BC fails and not fixedValue
Regards
manu |
