| nikovasi |
June 21, 2023 08:08 |
Unphysical pressure in channel Poiseuille flow
3 Attachment(s)
Hi guys,
I'm trying to solve the steady-state laminar compresible Poiseuille flow through a 2D channel using rhoSimpleFoam.
The rhoSimpleFoam solver converges and for the most part the solution looks reasonable as seen in the attached images. However, taking a closer look at the outlet, a weird behaviour is seen for the pressure.
I have tried using a finer mesh and also played around with fvSchemes and fvSolution controls but this behaviour persists and even becomes worse in some cases.
I have also tried rhoPimpleFoam. In that case, when steady-state is reached, I don't get the exact same behaviour seen with rhoSimpleFoam but the pressure shows a "wavy" profile near the outlet.
Since this is a pretty simple case I expect that someone else has encountered something similar? Any help will be greatly appreciated. Thanks!
blockMeshDict
Code:
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.7.1 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
root "";
case "";
instance "";
local "";
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
scale 1e0;
vertices
(
(0 0 0)
(2e-5 0 0)
(2e-5 5e-7 0)
(0 5e-7 0)
(0 0 5e-8)
(2e-5 0 5e-8)
(2e-5 5e-7 5e-8)
(0 5e-7 5e-8)
);
blocks
(
hex (0 1 2 3 4 5 6 7) dsmcZone (1000 50 1) simpleGrading (1 1 1)
);
boundary
(
inlet
{
type patch;
faces
(
(0 4 7 3)
);
}
outlet
{
type patch;
faces
(
(1 2 6 5)
);
}
wall
{
type wall;
faces
(
(7 6 2 3)
);
}
symmetry
{
type symmetryPlane;
faces
(
(4 5 1 0)
);
}
empty
{
type empty;
faces
(
(4 5 6 7)
(0 3 2 1)
);
}
);
mergePatchPairs
(
);
// ************************************************************************* //
thermoProperties
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.4.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "constant";
object thermophysicalProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
thermoType
{
type hePsiThermo;
mixture pureMixture;
transport const;
thermo hConst;
equationOfState perfectGas;
specie specie;
energy sensibleInternalEnergy;
}
mixture
{
specie
{
molWeight 39.93;
}
thermodynamics
{
Cp 520.33;
Hf 0;
}
transport
{
mu 2.117e-5;
Pr 0.666667;
}
}
// ************************************************************************* //
p
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2206 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
arch "LSB;label=32;scalar=64";
class volScalarField;
location "0";
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [1 -1 -2 0 0 0 0];
internalField uniform 20000;
boundaryField
{
inlet
{
type totalPressure;
gamma 1.66667;
p0 uniform 100000;
value uniform 100000;
}
outlet
{
type fixedValue;
value uniform 20000;
}
wall
{
type zeroGradient;
}
symmetry
{
type symmetryPlane;
}
empty
{
type empty;
}
}
// ************************************************************************* //
T
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2206 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
arch "LSB;label=32;scalar=64";
class volScalarField;
location "0";
object T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 0 0 1 0 0 0];
internalField uniform 300;
boundaryField
{
inlet
{
type totalTemperature;
gamma 1.66667;
T0 uniform 300;
value uniform 300;
}
outlet
{
type zeroGradient;
}
wall
{
type fixedValue;
value uniform 300;
}
symmetry
{
type symmetryPlane;
}
empty
{
type empty;
}
}
// ************************************************************************* //
U
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2206 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
arch "LSB;label=32;scalar=64";
class volVectorField;
location "0";
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];
internalField uniform (0 0 0);
boundaryField
{
inlet
{
type pressureInletVelocity;
value uniform (0 0 0);
}
outlet
{
type zeroGradient;
}
wall
{
type fixedValue;
value uniform (0 0 0);
}
symmetry
{
type symmetryPlane;
}
empty
{
type empty;
}
}
// ************************************************************************* //
fvSchemes
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2206 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
ddtSchemes
{
default steadyState;
}
gradSchemes
{
default Gauss linear;
}
divSchemes
{
default Gauss linear;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}
laplacianSchemes
{
default Gauss linear corrected;
}
interpolationSchemes
{
default linear;
}
snGradSchemes
{
default corrected;
}
wallDist
{
method meshWave;
}
// ************************************************************************* //
fvSolution
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2206 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solvers
{
p
{
solver GAMG;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-06;
relTol 0.0;
minIter 3;
maxIter 100;
nCellsInCoarsestLevel 100;
}
"(U|e)"
{
solver PBiCGStab;
preconditioner DILU;
minIter 3;
maxIter 100;
tolerance 1e-8;
relTol 0.0;
}
}
SIMPLE
{
momentumPredictor yes;
transonic yes;
nNonOrthogonalCorrectors 1;
turbOnFinalIterOnly false;
residualControl
{
p 1e-5;
U 1e-7;
e 1e-6;
}
}
relaxationFactors
{
equations
{
p 0.3;
U 0.7;
e 0.7;
}
}
// ************************************************************************* //
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