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May 24, 2013, 08:45 |
Non-orthogonality and pressure jumps
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New Member
Florian
Join Date: May 2013
Posts: 12
Rep Power: 13 |
Hello everyone,
I am facing a problem with my simulation. I try to simulate a particle within a tubeflow. It is a steady state problem. The velocity profile works perfectly, but all my simulations lead to pressure jumps around the particle and on the surface of the particle. They seem to be caused by the non-orthogonality of the mesh, because they only appear near the particle where the mesh changes. pressure jumps1.JPG pressure jumps2.JPG I tried different things to solve this problem. First I raised nNonOrthogonalCorrectors to 2, 3, 5 and even 15, but the problem still appeared. I also changed in fvschemes sngradschemes and laplacianschemes from “corrected” to “limited 0,333”, but still nothing changed. Last I changed the solver for p (GAMG-->PCG), but there were still pressure jumps. I use simpleFoam as a solver and I attached the fvschemes, fvsoluten, controldict and the result of the checkMesh to this post. Thank you in advance. controlDict Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.2.0 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object controlDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // application simpleFoam; startFrom latestTime; startTime 0; stopAt endTime; endTime 20000; deltaT 1; writeControl timeStep; writeInterval 200; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression off; timeFormat general; timePrecision 6; runTimeModifiable true; functions ( forces { type forces; functionObjectLibs ("libforces.so"); outputControl timeStep; outputInterval 50; patches (CYLINDER); // pname p; // Uname U; rhoName rhoInf; log true; // write force data to standard output rhoInf 998.21; // reference rho CofR (0.03 0 0.00315); // Center of rotation } ); // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.2.0 | | \\ / 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(p) Gauss linear; grad(U) Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss linearUpwind grad(U); div(phi,nuTilda) bounded Gauss linearUpwind grad(nuTilda); 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(DnuTildaEff,nuTilda) Gauss linear corrected; laplacian(1,p) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(U) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p ; } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.2.0 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { p { solver GAMG; tolerance 1e-08; relTol 0.1; smoother GaussSeidel; nPreSweeps 1; nPostSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 836; agglomerator faceAreaPair; mergeLevels 1; } U { solver smoothSolver; smoother GaussSeidel; nSweeps 2; tolerance 1e-08; relTol 0.1; } nuTilda { solver smoothSolver; smoother GaussSeidel; nSweeps 2; tolerance 1e-08; relTol 0.1; } } SIMPLE { nNonOrthogonalCorrectors 0; pRefCell 0; pRefValue 0; residualControl { p 1e-5; U 1e-5; nuTilda 1e-5; } } relaxationFactors { fields { p 0.3; } equations { U 0.7; nuTilda 0.7; } } // ************************************************************************* // Code:
/*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.2.0 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : 2.2.0-5be49240882f Exec : checkMesh Date : May 24 2013 Time : 14:28:58 Host : "sm-pc32-l" PID : 5965 Case : /home/likewise-open/BCINET/stoeckf/OpenFOAM/stoeckf-2.2.0/run/Versuch2Reihe2 nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 733616 faces: 2155759 internal faces: 2111465 cells: 711204 faces per cell: 6 boundary patches: 5 point zones: 0 face zones: 1 cell zones: 1 Overall number of cells of each type: hexahedra: 711204 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology CYLINDER 4485 4564 ok (non-closed singly connected) WALL 9779 9984 ok (non-closed singly connected) OUTLET.2 3744 3842 ok (non-closed singly connected) INLET.1 3744 3842 ok (non-closed singly connected) SYMMETRY 22542 22864 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (0.02 -0.00499844 -0.005) (0.04 6.02937e-14 0.005) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (1.09137e-16 3.82779e-16 -7.56275e-17) OK. Max cell openness = 3.28499e-16 OK. Max aspect ratio = 15.0684 OK. Minimum face area = 1.16736e-10. Maximum face area = 9.15643e-08. Face area magnitudes OK. Min volume = 1.25716e-15. Max volume = 9.58542e-12. Total volume = 7.84868e-07. Cell volumes OK. Mesh non-orthogonality Max: 57.1982 average: 14.0225 Non-orthogonality check OK. Face pyramids OK. Max skewness = 1.11139 OK. Coupled point location match (average 0) OK. Mesh OK. |
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Tags |
orthogonal, pressure jump, simplefoam |
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