# Solution divergence in pisoFoam (Co <1)

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 May 16, 2012, 21:35 Solution divergence in pisoFoam (Co <1) #1 Member   Jeong Kim Join Date: Feb 2010 Posts: 42 Rep Power: 9 Sponsored Links I did not understand why the solution diverged even though Co was less than 1 and mesh quality of an expansion channel looked very good. (only hexahedral meshes used.) I confirmed that the solution converged using simpleFoam, but I have to use pisoFoam. Could you please how I can make the solution converged? Solver: pisoFoam time step: 0.00001 Time = 0.00127 Courant Number mean: 0.000311654 max: 0.050861 DILUPBiCG: Solving for Ux, Initial residual = 0.218313, Final residual = 5.69983e-06, No Iterations 7 DILUPBiCG: Solving for Uy, Initial residual = 0.629777, Final residual = 7.26245e-06, No Iterations 8 DILUPBiCG: Solving for Uz, Initial residual = 0.813262, Final residual = 4.59516e-06, No Iterations 9 DICPCG: Solving for p, Initial residual = 0.0588425, Final residual = 0.00573561, No Iterations 13 time step continuity errors : sum local = 1.09564e-06, global = 2.10204e-07, cumulative = 2.01415e-07 DICPCG: Solving for p, Initial residual = 0.0395018, Final residual = 9.25134e-07, No Iterations 832 time step continuity errors : sum local = 1.76973e-10, global = 2.61937e-13, cumulative = 2.01415e-07 ExecutionTime = 7006.28 s ClockTime = 7024 s Time = 0.00128 Courant Number mean: 0.000312157 max: 0.0554556 DILUPBiCG: Solving for Ux, Initial residual = 0.502578, Final residual = 4.21354e-06, No Iterations 8 DILUPBiCG: Solving for Uy, Initial residual = 0.720687, Final residual = 4.78693e-06, No Iterations 9 DILUPBiCG: Solving for Uz, Initial residual = 0.817737, Final residual = 4.35604e-06, No Iterations 9 ^C === checkMesh /*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.1.0 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : 2.1.0-0bc225064152 Exec : checkMesh Date : May 16 2012 Time : 21:18:25 Host : "Aspire" PID : 11943 Case : /home/OpenFOAM/jeong-2.1.0/run/pisoFoam/ras/expChannel 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: 1286100 faces: 3718487 internal faces: 3581509 cells: 1216666 boundary patches: 3 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 1216666 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 WALL 134426 134572 ok (non-closed singly connected) IN 841 900 ok (non-closed singly connected) OUT 1711 1800 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (-0.002 -0.0001 -3.46945e-21) (0.004 0.0001 0.0001) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (2.56678e-17 -7.99211e-15 -9.73591e-20) OK. Max cell openness = 3.50175e-16 OK. Max aspect ratio = 7.66351 OK. Minumum face area = 9.68955e-13. Maximum face area = 4.58198e-11. Face area magnitudes OK. Min volume = 9.68962e-19. Max volume = 2.44793e-16. Total volume = 1e-10. Cell volumes OK. Mesh non-orthogonality Max: 0.526672 average: 0.0961124 Non-orthogonality check OK. Face pyramids OK. Max skewness = 3.0378 OK. Coupled point location match (average 0) OK. Mesh OK. End

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