1 Attachment(s)
Any guesses?
I used pimpleFoam to simulate the flow around a NACA0012 airfoil and the following settings:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \ / 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;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
ddtSchemes
{
default backward;
}
gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}
divSchemes
{
default none;
div(phi,U) Gauss limitedLinearV 1;
div(phi,k) Gauss upwind;
div(phi,omega) Gauss upwind;
div((nuEff*dev(grad(U).T()))) Gauss linear;
}
laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear corrected;
laplacian((1|A(U)),p) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DomegaEff,omega) Gauss linear corrected;
}
interpolationSchemes
{
default linear;
interpolate(U) linear;
}
snGradSchemes
{
default corrected;
}
fluxRequired
{
default no;
p ;
}
// ************************************************************************* //
Code:
/*--------------------------------*- C++ -*----------------------------------*\n| ========= | |
| \ / 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;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solvers
{
p
{
solver GAMG;
tolerance 1e-7;
relTol 0;
mergeLevels 1;
smoother GaussSeidel;
agglomerator faceAreaPair ;
nCellsInCoarsestLevel 100;
nPreSweeps 0;
nPostSweeps 2;
cacheAgglomeration true;
}
pFinal
{
solver GAMG;
tolerance 1e-7;
relTol 0;
mergeLevels 1;
smoother GaussSeidel;
agglomerator faceAreaPair ;
nCellsInCoarsestLevel 100;
nPreSweeps 0;
nPostSweeps 2;
cacheAgglomeration true;
}
U
{
solver smoothSolver;
tolerance 1e-7;
relTol 0;
nSweeps 2;
smoother GaussSeidel;
}
UFinal
{
solver smoothSolver;
tolerance 1e-7;
relTol 0;
nSweeps 2;
smoother GaussSeidel;
}
k
{
solver smoothSolver;
smoother GaussSeidel ;
nSweeps 1 ;
tolerance 1e-7;
relTol 0;
}
omega
{
solver smoothSolver;
smoother GaussSeidel ;
nSweeps 1 ;
tolerance 1e-7;
relTol 0;
};
}
PIMPLE
{
nNonOrthogonalCorrectors 4;
pRefValue 1;
pRefCell 0;
nOuterCorrectors 10;
nCorrectors 2;
};
relaxationFactors
{
default 1;
p 0.5;
U 0.5;
k 0.5;
omega 0.5;
};
}
// ************************************************************************* //
However,I made two strange observations:
1) Even-tough the aerodynamic coefficients get in absolute close to zero, they change significantly from one iteration to the other (see attached file).
2) The velocity field converges from the first outer iteration while the pressure needs couple iteration to get physical.
Do anyone has already experienced something similar?
Thanks in advance!
L1011 |
