# SimpleFoam high order schemes

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 September 18, 2017, 09:43 SimpleFoam high order schemes #1 Member   Vedamt Chittlangia Join Date: Feb 2016 Posts: 64 Rep Power: 9 Hello, I am simulating flow around vane cascade. I have good mesh quality with checkMesh reporting OK for all checks and the maximum non-orthogonality at 41. I was able to get converged solution with first order schemes (bounded Gauss upwind) but when i switched to higher order schemes, my solution diverged with 'Nan'. Solver: simpleFoam RASModel: LaunderSharmaKE (or kOmegaSST) Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.2.2 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(U) leastSquares; grad(T) leastSquares; } divSchemes { default none; div(phi,U) bounded Gauss linearUpwind grad(U); div(phi,k) bounded Gauss linearUpwind default; div(phi,epsilon) bounded Gauss upwind; div(phi,R) bounded Gauss linearUpwind default; div(phi,nuTilda) bounded Gauss linearUpwind default; div((nuEff*dev(T(grad(U))))) Gauss linear; div(phi,T) bounded Gauss linearUpwind grad(T); } laplacianSchemes { default Gauss linear corrected; laplacian(1,Phi) Gauss linear corrected;// limited 0.5; laplacian(nuEff,U) Gauss linear corrected;// limited 0.5; laplacian((1|A(U)),p) Gauss linear corrected;// limited 0.5; laplacian(DkEff,k) Gauss linear corrected;// limited 0.5; laplacian(DepsilonEff,epsilon) Gauss linear corrected;// limited 0.5; laplacian(DREff,R) Gauss linear corrected;// limited 0.5; laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;// limited 0.5; laplacian(kappaEff,T) Gauss linear corrected;// limited 0.5; } interpolationSchemes { default linear; interpolate(U) linear; interpolate(T) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p ; Phi; } // ************************************************************************* //``` Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.2.2 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { Phi { solver GAMG; smoother DIC;//GaussSeidel; cacheAgglomeration on; agglomerator faceAreaPair; nCellsInCoarsestLevel 10; mergeLevels 1; tolerance 1e-6; relTol 0.01; } p { solver PCG; preconditioner DIC; tolerance 1e-12; relTol 0.0001; //maxIter 200; /* solver GAMG; tolerance 1e-08; relTol 0.001; minIter 5; //added later maxIter 200; //added later smoother GaussSeidel; // DIC; //DICGaussSeidel; //FDIC; nPreSweeps 1; nPostSweeps 3; nFinestSweeps 3; cacheAgglomeration true; nCellsInCoarsestLevel 100; agglomerator faceAreaPair; mergeLevels 1; */ } /* pFinal { \$p; relTol 0; } */ "(U|T|k|epsilon)" { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0.1; /* solver smoothSolver; smoother GaussSeidel; tolerance 1e-3; relTol 0; */ } "(R|nuTilda)" { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0.1; /* solver smoothSolver; smoother GaussSeidel; tolerance 1e-3; relTol 0; */ } } SIMPLE { nNonOrthogonalCorrectors 0; residualControl { p 1e-8; U 1e-8; k 1e-8; epsilon 1e-8; T 1e-8; } } potentialFlow { nNonOrthogonalCorrectors 10; } relaxationFactors { fields { p 0.1; } equations { default 0.3; U 0.5; k 0.5; epsilon 0.5; R 0.4; T 0.6; nuTilda 0.4; } } // ************************************************************************* //``` It would be really great if someone has suggestions for me. Thanks

 September 18, 2017, 23:45 #2 Member   Ping Chang Join Date: Feb 2016 Location: Perth Posts: 93 Rep Power: 10 Hi, Could you please post your log file?

 September 19, 2017, 11:38 log files #3 Member   Vedamt Chittlangia Join Date: Feb 2016 Posts: 64 Rep Power: 9 Hello Ping, I had tried several fvSchemes options for divergence before settling on the ones that I mentioned. My log files are for kwSST model where omega is bounded Gauss upwind and all other are same. Link to log files Thanks

 Tags accuracy, fvschemes, komegasst, simplefoam convergence

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