CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM Running, Solving & CFD (http://www.cfd-online.com/Forums/openfoam-solving/)
-   -   Von Karman street simulation with icoFoam (http://www.cfd-online.com/Forums/openfoam-solving/59153-von-karman-street-simulation-icofoam.html)

agrewal February 7, 2008 15:11

I'm trying to run a 2-D vortex
 
I'm trying to run a 2-D vortex shedding simulation with a circular cylinder in icoFoam. The conditions are u=1 m/s, d = 0.05 m and the comp domain is 1 m in the x direction and 0.5 m in the y-direction.

The BCs are inlet, outlet and symmetric at the top and bottom.

I am using a integration time step of 1e-4 with the following schemes:

ddtSchemes
{
default CrankNicholson 0.5;
}

gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss limitedLinearV 1;
}

laplacianSchemes
{
default none;
laplacian(nu,U) Gauss linear corrected;
laplacian((1|A(U)),p) Gauss linear corrected;
}

interpolationSchemes
{
default linear;
interpolate(HbyA) linear;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p;
}

I also used the following solver settings:

solvers
{
p PCG
{
tolerance 1e-07;
relTol 0;
preconditioner DIC;
};
U smoothSolver
{
tolerance 1e-07;
relTol 0;
smoother GaussSeidel;
nSweeps 1;
};
}

PISO
{
momentumPredictor yes;
nCorrectors 2;
nNonOrthogonalCorrectors 2;
pRefCell 0;
pRefValue 0;
}

Before shedding starts, the Courant no blows up and the following message is seen:

#0 Foam::error::printStack(Foam:http://www.cfd-online.com/OpenFOAM_D...part/proud.gifstream&) in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted: [0xb7f08420]
#3 Foam::GaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<foam::field,> const&, Foam::UPtrList<foam::lduinterfacefield> const&, unsigned char, int) in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 Foam::GaussSeidelSmoother::smooth(Foam::Field<doub le>&, Foam::Field<double> const&, unsigned char, int) const in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"ddtSche mes
#5 Foam::smoothSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#6 Foam::fvMatrix<foam::vector<double> >::solve(Foam::Istream&) in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/icoFoam"
#7 Foam::lduMatrix::solverPerformance Foam::solve<foam::vector<double> >(Foam::tmp<foam::fvmatrix<foam::vector<double> > > const&) in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/icoFoam"
#8 main in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/icoFoam"
#9 __libc_start_main in "/lib/i686/libc.so.6"
#10 Foam::regIOobject::readIfModified() in "/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/icoFoam"

Until 0.269 sec, the max Courant # is stable at 0.088, and then starts ramping up.

I use an unstructured mesh with ~9500 tetrahedral prisms. As the solution develops, the outlet region has high velocity including flow reversal that isn't transported from the cylinder. CheckMesh does not report any errors. What am I doing wrong?
Thanks
Anant

agrewal February 7, 2008 17:22

BTW, The Reynolds no is approx
 
BTW, The Reynolds no is approx 350. I am reducing the time step by 10 to see if this overcomes the problem.
Anant

lakeat February 9, 2008 04:14

Email your case/ 0, constant a
 
Email your case/ 0, constant and system to me, and let me have a look.

Daniel

marhamat February 9, 2008 18:12

what's about your mesh? Is th
 
what's about your mesh?
Is the mesh orthogonal enough?


All times are GMT -4. The time now is 15:52.