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rhoSimpleFoam, convergence to zero flow

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Old   March 5, 2016, 15:44
Question rhoSimpleFoam, convergence to zero flow
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Peter S.
Join Date: Mar 2016
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Hi,

I am entirely new to this forum and relatively new to OpenFoam. I adress this forum, because I am completely stuck.

I am trying to simulate air flow through a nozzle with rhoSimpleFoam. Geometry was made with Salome, (background)meshed with blockMesh, refined with snappyHexmesh. the mesh looks good; checkMesh confirms this.

I used all files for 0, constant and system from the rhoSimpleFoam tutorial angled duct (of course I changed blockMeshDict and snappyHexMeshDict) and put the nozzle-geometry in triSurface (in constant).

After some changes the simulation converges but strangely enough it converges to zero flow. This is strange because in the 0/U file for the inlet-patch, I used flowRateInletVelocity and massFlowRate of 0.029 kg/s.

I already tried replacing the nozzle-geometry with a simple straight pipe geometry, use identical files in 0, constant and system (except geometry-files). the simulation converges to a flow of zero !!!

I am struggling with this issue for more than a month now and am probably getting blind for the real cause.

can anyone help me ?
I can share any file required.

Thanks and best regards,

Peter
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Old   March 6, 2016, 06:18
Default files for this case
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Peter S.
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dear all,

To enable people to offer any help, below I post the files in 0, and the files fvSchemes and fvSolutions from system.

looking forward to any help.

Peter.


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

internalField uniform 0;

boundaryField
{
wall
{
type compressible::alphatWallFunction;
Prt 0.85;
value uniform 0;
}
inlet
{
type calculated;
value uniform 0;
}
outlet
{
type calculated;
value uniform 0;
}
}

epsilon:
dimensions [0 2 -3 0 0 0 0];

internalField uniform 200;

boundaryField
{
wall
{
type epsilonWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 200;
}
inlet
{
type turbulentMixingLengthDissipationRateInlet;
mixingLength 0.005;
value uniform 200;
}
outlet
{
type inletOutlet;
inletValue uniform 200;
value uniform 200;
}
}

k:
kInlet 1;

dimensions [0 2 -2 0 0 0 0];

internalField uniform $kInlet;

boundaryField
{
inlet
{
type turbulentIntensityKineticEnergyInlet;
intensity 0.05;
value uniform $kInlet;
}

outlet
{
type inletOutlet;
inletValue uniform $kInlet;
value uniform $kInlet;
}

wall
{
type kqRWallFunction;
value uniform $kInlet;
}

}

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

internalField uniform 0;

boundaryField
{
inlet
{
type calculated;
value uniform 0;
}

outlet
{
type calculated;
value uniform 0;
}

wall
{
type nutkWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0;
}

}

p:
pOut 110000;

dimensions [1 -1 -2 0 0 0 0];//

internalField uniform $pOut;

boundaryField
{
inlet
{
type zeroGradient;
refValue uniform $pOut;
refGradient uniform 0;
valueFraction uniform 0.3;
}

outlet
{
type fixedValue;
value uniform $pOut;
}

wall
{
type zeroGradient;
}

}

T:
Tinlet 413;

dimensions [0 0 0 1 0 0 0];

internalField uniform $Tinlet;

boundaryField
{
wall
{
type zeroGradient;
}

inlet
{
type fixedValue;
value uniform $Tinlet;
}

outlet
{
type inletOutlet;
value uniform 413;
inletValue uniform 413;
}
}

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

internalField uniform (0 0 0);

boundaryField
{
inlet
{
type flowRateInletVelocity;
massFlowRate constant 0.029;
rhoInlet 1.1;

}

outlet
{
type inletOutlet;
value uniform (0 0 0);
inletValue uniform (0 0 0);
}

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

fvSchemes:
}
dtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
default none;

div(phi,U) bounded Gauss upwind;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
div(phi,e) bounded Gauss upwind;
div(phi,epsilon) bounded Gauss upwind;
div(phi,k) bounded Gauss upwind;

div(phid,p) bounded Gauss upwind;
div(phi,Ekp) bounded Gauss upwind;
div((phi|interpolate(rho)),p) Gauss upwind;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;

fvSolution:
solvers
{
p
{
solver GAMG;
tolerance 1e-08;
relTol 0.1;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
nFinestSweeps 2;
cacheAgglomeration true;
nCellsInCoarsestLevel 20;
agglomerator faceAreaPair;
mergeLevels 1;
}

"(U|e|k|epsilon)"
{
solver GAMG;
tolerance 1e-08;
relTol 0.1;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
nFinestSweeps 2;
cacheAgglomeration true;
nCellsInCoarsestLevel 20;
agglomerator faceAreaPair;
mergeLevels 1;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 0;
rhoMin 0.1;
rhoMax 1.0;
transonic yes;
consistent yes;

pRefPoint (0.01 0.01 0.01);
pRefValue 0;

residualControl
{
p 1e-3;
U 1e-4;
e 1e-3;
// possibly check turbulence fields
"(k|epsilon|omega)" 1e-3;
}
}

relaxationFactors
{
fields
{
p 1;
rho 1;
}
equations
{
p 1;
U 0.9;
e 0.9;
k 0.9;
epsilon 0.9;
}
}
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