| ponghe |
April 3, 2020 16:52 |
rhoSimpleFoam can't converge at high velocity duct flow
1 Attachment(s)
Hi everyone,
Wonder if you ran into similar problem with rhoSimpleFoam when simulating high velocity 3D duct flow.
I have an exhaust plenum with inlet velocity at 160 m/s and 490 deg C (Ma=0.2-0.3).
The geometry looks something like this:
https://www.cfd-online.com/Forums/at...1&d=1585946075
My fvSolution setup as follow:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \ / O peration | Version: 2.2.0 |
| \ / A nd | Web: www.OpenFOAM.org |
| \/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solvers
{
p
{
solver GAMG;
tolerance 1e-08;
relTol 0.05;
smoother GaussSeidel;
// cacheAgglomeration off;
nCellsInCoarsestLevel 19; //sqrt(nCells)
// agglomerator faceAreaPair;
// mergeLevels 1;
}
h
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-06;
relTol 0.01;
}
"(U|k|epsilon)"
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-07;
relTol 0.01;
}
}
SIMPLE
{
nUCorrectors 2;
nNonOrthogonalCorrectors 0;
pMinFactor 0.8;
pMaxFactor 1.3;
residualControl
{
p 1e-6;
U 1e-5;
h 1e-5;
k 1e-5;
epsilon 1e-5;
omega 1e-5;
}
}
relaxationFactors
{
fields
{
p 0.5;
rho 0.8;
}
equations
{
U 0.5;
"(k|epsilon)" 0.5;
h 0.5;
}
}
// ************************************************************************* //
My fvScheme is "run of the mill". I didn't bother tuning it yet.
Basically my solution never converges no matter how fine the mesh becomes. The pressure residual always oscillates substantial amounts (-1e5 to 5e5 every couple of iteration steps)
I also have tried running this case in of2.3 and of6 and found no differences.
At low flows of 40 m/s or less, my solutions converges very nicely.
Much appreciated if someone can shed some lights on this! |
