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November 3, 2011, 07:33 |
No convergence
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#1 |
New Member
Denis
Join Date: Jul 2011
Posts: 8
Rep Power: 14 |
Hi,
i'm trying to simulate a 2D flow over an airfoil. I'm using the simpleFoam with a k-epsilon turbulence model, these are my system files: fvSolution: Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.0.1 | | \\ / 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-06; relTol 0.1; smoother GaussSeidel; nPreSweeps 0; nPostSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; } U { solver PBiCG; preconditioner DILU; tolerance 1e-05; relTol 0.1; } k { solver PBiCG; preconditioner DILU; tolerance 1e-05; relTol 0.1; } epsilon { solver PBiCG; preconditioner DILU; tolerance 1e-05; relTol 0.1; } } SIMPLE { nNonOrthogonalCorrectors 0; pRefCell 10; pRefValue 0; residualControl { p 1e-6; U 1e-6; "(k|epsilon|omega)" 1e-3; } } relaxationFactors { p 0.3; U 0.7; k 0.7; epsilon 0.7; // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.0.1 | | \\ / A nd | Web: www.OpenFOAM.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; } divSchemes { default none; div(phi,U) Gauss upwind; div(phi,k) Gauss upwind; div(phi,epsilon) Gauss upwind; div((nuEff*dev(T(grad(U))))) 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(DepsilonEff,epsilon) Gauss linear corrected; laplacian(DREff,R) Gauss linear corrected; laplacian(DnuTildaEff,nuTilda) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(U) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p ; } // ************************************************************************* // Code:
#0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam201/platforms/linuxGccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam201/platforms/linuxGccDPOpt/lib/libOpenFOAM.so" #2 Uninterpreted: #3 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam201/platforms/linuxGccDPOpt/lib/libOpenFOAM.so" #4 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam201/platforms/linuxGccDPOpt/lib/libfiniteVolume.so" #5 Foam::fvMatrix<double>::solve() in "/opt/openfoam201/platforms/linuxGccDPOpt/bin/simpleFoam" #6 Foam::incompressible::RASModels::kEpsilon::correct() in "/opt/openfoam201/platforms/linuxGccDPOpt/lib/libincompressibleRASModels.so" #7 in "/opt/openfoam201/platforms/linuxGccDPOpt/bin/simpleFoam" #8 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6" #9 in "/opt/openfoam201/platforms/linuxGccDPOpt/bin/simpleFoam" Gleitkomma-Ausnahme Denis |
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November 3, 2011, 07:40 |
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#2 |
Senior Member
Bernhard
Join Date: Sep 2009
Location: Delft
Posts: 790
Rep Power: 21 |
It is easier to understand to post a larger part of the log file (before the actual error occurs).
In this case you put relTol to 0.1, which seems high to me. Try to pose a more strict condition on this one. |
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November 3, 2011, 08:14 |
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#3 |
New Member
Denis
Join Date: Jul 2011
Posts: 8
Rep Power: 14 |
Hi Bernhard,
thank you for your fast response. So I've changed the tol, maybe you can explain me, what´s the difference between "relTol" and "tolerance". I attached a plot of the residuals: there you can see a "zig-zacking" of all residuals and you can see that they are "bounded". Do you have an explanation for that? Denis |
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November 21, 2011, 20:20 |
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#4 |
Member
HD
Join Date: Jul 2011
Posts: 56
Rep Power: 14 |
Hi Denis,
I got the same error running simpleFoam, I wonder if you have resolved this issue. If so, could you post the solution? Thank you! Best, Hang |
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November 22, 2011, 00:03 |
relTol and tolerance
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#5 |
Member
Geon-Hong Kim
Join Date: Feb 2010
Location: Ulsan, Republic of Korea
Posts: 36
Rep Power: 16 |
Hi Denis.
Both tolerance and relTol are used for terminating a sub-iteration of each equation. If the residual reaches tolerance or becomes less than the tolerance you set, then the computation of corresponding equation will be terminated. If the residual reaches or goes to below than (relTol) x (Initial residual), then the iteration will be terminated as well. When you set the relTol as 0, then the iteration will be terminated only if the final residual becomes less than the tolerance. Regards, Geon-Hong. |
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