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strange result for non-orthogonality mesh using icoFoam |
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October 31, 2013, 23:08 |
strange result for non-orthogonality mesh using icoFoam
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#1 |
New Member
JM
Join Date: Jul 2013
Posts: 7
Rep Power: 13 |
hello everyone
I am simulating a duct flow with icoFoam. I use periodic boundary condition for inlet and outlet.The other boundary condition I set as no-slip. I have attached the velocity profile here.You can find that there are some velocity jumps which I think affected by the mesh. The followings are the fvschemes, fvsolution, and the result of the checkMesh. Thank you in advance. fvSchemes Code:
ddtSchemes { default Euler; } gradSchemes { default cellMDLimited leastSquares 1; // grad(p) Gauss linear; } divSchemes { default none; div(phi,U) Gauss reconCentral cellLimited leastSquares 1.0; div(phi) Gauss linearUpwindV cellMDLimited leastSquares 1.0; } laplacianSchemes { default Gauss linear corrected; laplacian(nu,U) Gauss linear corrected; laplacian((1|A(U)),p) Gauss linear corrected; laplacian(DT,T) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(HbyA) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; } Code:
solvers { p { solver PCG; preconditioner DIC; tolerance 1e-08; relTol 0; }; U { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0; }; } PISO { nCorrectors 3; nNonOrthogonalCorrectors 2; pRefCell 0; pRefValue 0; } Code:
Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 48548 faces: 119960 internal faces: 94888 cells: 35808 boundary patches: 2 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 35808 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 0 Checking topology... Boundary definition 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 INTERFACE 1200 1600 ok (non-closed singly connected) inout 23872 24274 ok (non-closed singly connected) Checking geometry... This is a 3-D mesh Overall domain bounding box (-1 -1 -4.33680869e-19) (1 1 0.01999999955) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Mesh (non-empty, non-wedge) dimensions 3 Boundary openness (6.5506050833e-20 -8.7921189539e-20 -1.6233662817e-19) Threshold = 1e-06 OK. Max cell openness = 2.1714371522e-16 OK. Max aspect ratio = 350.00000279 OK. Minumum face area = 9.999999e-08. Maximum face area = 0.0011896420623. Face area magnitudes OK. Min volume = 6.6666658486e-10. Max volume = 7.9309469101e-06. Total volume = 0.0799999982. Cell volumes OK. Mesh non-orthogonality Max: 44.27477573 average: 9.93239561 Threshold = 70 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.57381680369 OK. Mesh OK. End xiaof |
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November 2, 2013, 07:48 |
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#2 |
Senior Member
Nicolas Edh
Join Date: Mar 2010
Location: Uppsala, Sweden
Posts: 123
Rep Power: 18 |
Hi xiof,
I don't have any indepth knowledge of the schemes you are using but I would try to switch to a second order time stepping scheme like backward or CrankNicolson. Secondly are you sure that the velocity jump isn't an artifact of the warping? Is it still there if you make a a linear plot? Best Nicolas |
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