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interFoam blows up with small channels and high pressure

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Old   March 7, 2014, 05:49
Default interFoam blows up with small channels and high pressure
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Hi everybody,

I am running an interFoam case with some microchannels connected to two manifolds, one with the inlet and one with the outlet:

_________0 <-outlet
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
0------------
|
inlet

I hope thats understandable
I can run the case with 1500 Pa pressure at the inlet. The Channels are filled with air at the start and then get flooded with a fluid. It works up to 15 sec and the result looks quite good.
Now I want to have higher pressure at my inlet, but the courant number blows up at =~0.0001 s, or the timesteps for adjustableTimeSteps are getting to small.

My setup:

alpha.coolant:
dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{
wall
{
type zeroGradient;
}
inlet
{
type fixedValue;
value uniform 1;
}
outlet
{
type inletOutlet;
inletValue uniform 1;
value uniform 1;
}
}

p_rgh:
dimensions [1 -1 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
wall
{
type fixedFluxPressure;
value uniform 0;
}

inlet
{
type fixedValue;
value uniform 5e5;
}
outlet
{
type fixedValue;
value uniform 0;
}

}

U:
dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
wall
{
type fixedValue;
value uniform (0 0 0);
}

inlet
{
type pressureInletVelocity;
value uniform ( 0 0 0 );
}
outlet
{
type zeroGradient;
}

}

fvSchemes:
ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
div(rhoPhi,U) Gauss linearUpwind grad(U);
div(phi,alpha) Gauss vanLeer;
div(phirb,alpha) Gauss linear;
div((muEff*dev(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear limited 0.33;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default limited 0.33;
}

fluxRequired
{
default no;
p_rgh;
pcorr;
alpha.coolant;
}

fvSolutions:
solvers
{

"alpha.coolant.*"
{
nAlphaCorr 2;
nAlphaSubCycles 1;
alphaOuterCorrectors yes;
cAlpha 1;

MULESCorr yes;
nLimiterIter 3;

solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-8;
relTol 0;
}
pcorr
{
solver PCG;
preconditioner DIC;
tolerance 1e-5;
relTol 0;
}

p_rgh
{
solver PCG;
preconditioner DIC;
tolerance 1e-07;
relTol 0.05;
}

p_rghFinal
{
$p_rgh;
relTol 0;
}

U
{
solver smoothSolver; //PBiCG;
preconditioner symGaussSeidel; //DILU;
tolerance 1e-06;
relTol 0;
}
}

PIMPLE
{

momentumPredictor no;
nOuterCorrectors 1;
nCorrectors 3;
nNonOrthogonalCorrectors 2;
}

relaxationFactors
{
fields
{
}
equations
{
".*" 1;
}
}


Is there anything obvious that I overlooked? I work with the newest 2.3.0 OpenFoam version.
Thanks for your help.

Cheers
Nils
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