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Unstructrued Otype Mesh of a cylinder with icoFoam 

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December 2, 2016, 12:21 
SolverSetting for Unstructrued Otype Mesh of a cylinder icoFoam

#1 
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I have a poiseuille case to test on a simple cylinder. My objective is to run the Tjunction case with two identical cylinders.
Depending on meshing strategy : 1. structured grid with icoFoam defaut setting of tutorial cavity: BC inlet : pressure value1, outlet value2 => converge inlet : parabolic profile, outlet pressure ref=0 => converge see butterfly.png butterfly.png 2. Otype nonstructured mesh with settings above : BC inlet : pressure value1, outlet value2 => diverge Mesh looks like this : Otype.png checkMesh gives positive result : [tried to mesh with blockMeshDict with 6 points a hex block, that one doesn't pass the checkMesh] High aspect ratio but low nonorthogonality, max skewness = 0.3 Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 194481 faces: 578400 internal faces: 568800 cells: 192000 faces per cell: 5.975 boundary patches: 3 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 187200 prisms: 4800 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 inlet 2400 2401 ok (nonclosed singly connected) outlet 2400 2401 ok (nonclosed singly connected) walls 4800 4860 ok (nonclosed singly connected) Checking geometry... Overall domain bounding box (0.004 0.004 0) (0.004 0.004 0.016) Mesh has 3 geometric (nonempty/wedge) directions (1 1 1) Mesh has 3 solution (nonempty) directions (1 1 1) Boundary openness (2.77194e17 7.51513e17 4.67679e17) OK. Max cell openness = 3.40144e16 OK. Max aspect ratio = 38.2671 OK. Minimum face area = 5.22642e10. Maximum face area = 8.37375e08. Face area magnitudes OK. Min volume = 1.04528e13. Max volume = 8.25775e12. Total volume = 8.02779e07. Cell volumes OK. Mesh nonorthogonality Max: 1.70755e06 average: 0 Nonorthogonality check OK. Face pyramids OK. Max skewness = 0.329681 OK. Coupled point location match (average 0) OK. Mesh OK. End Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 PISO: Operating solver in PISO mode Reading transportProperties Reading field p Reading field U Reading/calculating face flux field phi Starting time loop Time = 1e05 Courant Number mean: 0 max: 0 DILUPBiCG: Solving for Ux, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Uy, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 4.70439e06, No Iterations 10 DICPCG: Solving for p, Initial residual = 1, Final residual = 8.60531e07, No Iterations 155 time step continuity errors : sum local = 4.69332e10, global = 3.74768e12, cumulative = 3.74768e12 DICPCG: Solving for p, Initial residual = 0.0545117, Final residual = 8.84748e07, No Iterations 138 time step continuity errors : sum local = 9.17592e10, global = 2.54215e12, cumulative = 1.20553e12 ExecutionTime = 0.41 s ClockTime = 1 s Time = 2e05 Courant Number mean: 0.000325844 max: 0.0219715 DILUPBiCG: Solving for Ux, Initial residual = 0.238504, Final residual = 9.33255e06, No Iterations 14 DILUPBiCG: Solving for Uy, Initial residual = 0.238507, Final residual = 5.95036e06, No Iterations 13 DILUPBiCG: Solving for Uz, Initial residual = 0.962651, Final residual = 8.51301e06, No Iterations 13 DICPCG: Solving for p, Initial residual = 0.00651103, Final residual = 9.86859e07, No Iterations 116 time step continuity errors : sum local = 9.67146e10, global = 2.79469e11, cumulative = 2.91524e11 DICPCG: Solving for p, Initial residual = 0.00214519, Final residual = 8.97386e07, No Iterations 110 time step continuity errors : sum local = 8.75932e10, global = 1.83468e11, cumulative = 4.74992e11 ExecutionTime = 0.59 s ClockTime = 2 s Time = 3e05 Courant Number mean: 0.000632862 max: 0.0123958 DILUPBiCG: Solving for Ux, Initial residual = 0.18138, Final residual = 8.22932e06, No Iterations 15 DILUPBiCG: Solving for Uy, Initial residual = 0.181399, Final residual = 6.14408e06, No Iterations 15 DILUPBiCG: Solving for Uz, Initial residual = 0.949986, Final residual = 5.35623e06, No Iterations 13 DICPCG: Solving for p, Initial residual = 0.007183, Final residual = 9.67958e07, No Iterations 112 time step continuity errors : sum local = 9.47447e10, global = 7.12456e11, cumulative = 1.18745e10 DICPCG: Solving for p, Initial residual = 0.0069341, Final residual = 9.04469e07, No Iterations 111 time step continuity errors : sum local = 8.87948e10, global = 3.0653e11, cumulative = 8.80917e11 ExecutionTime = 0.79 s ClockTime = 2 s Time = 4e05 Courant Number mean: 0.000939384 max: 0.0303498 DILUPBiCG: Solving for Ux, Initial residual = 0.428115, Final residual = 7.9459e06, No Iterations 16 DILUPBiCG: Solving for Uy, Initial residual = 0.428095, Final residual = 5.35738e06, No Iterations 16 DILUPBiCG: Solving for Uz, Initial residual = 0.906008, Final residual = 5.21517e06, No Iterations 13 DICPCG: Solving for p, Initial residual = 0.0276355, Final residual = 8.49123e07, No Iterations 119 time step continuity errors : sum local = 8.4924e10, global = 1.35349e11, cumulative = 7.45569e11 DICPCG: Solving for p, Initial residual = 0.0262004, Final residual = 8.13028e07, No Iterations 118 time step continuity errors : sum local = 8.23637e10, global = 1.30846e11, cumulative = 8.76415e11 ExecutionTime = 0.99 s ClockTime = 3 s ......... ......... ......... Time = 0.0001 Courant Number mean: 0.00791318 max: 11.8668 DILUPBiCG: Solving for Ux, Initial residual = 0.817916, Final residual = 7.72584e06, No Iterations 38 DILUPBiCG: Solving for Uy, Initial residual = 0.817695, Final residual = 2.27355e06, No Iterations 36 DILUPBiCG: Solving for Uz, Initial residual = 0.65771, Final residual = 8.97567e06, No Iterations 39 DICPCG: Solving for p, Initial residual = 0.702655, Final residual = 9.289e07, No Iterations 143 time step continuity errors : sum local = 1.72787e08, global = 7.38884e10, cumulative = 8.18707e10 DICPCG: Solving for p, Initial residual = 0.356256, Final residual = 8.647e07, No Iterations 143 time step continuity errors : sum local = 1.70898e08, global = 2.99532e10, cumulative = 1.11824e09 ExecutionTime = 2.37 s ClockTime = 5 s End Finalising parallel run pfirstTimeStep.png p at 10th timeStep p10timeStep.png So the pressure is not correctly solved. I search for the solver setting for unstructured grid of icoFoam : the "elbow" tutorial. Take that setting gives : have to set DeltaT=1e7 to avoid Code:
[12] #0 Foam::error::printStack(Foam::Ostream&) at ??:? [12] #1 Foam::sigFpe::sigHandler(int) at ??:? [12] #2 ? in "/usr/lib64/libc.so.6" [12] #3 Foam::symGaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, unsigned char, int) at ??:? [12] #4 Foam::symGaussSeidelSmoother::smooth(Foam::Field<double>&, Foam::Field<double> const&, unsigned char, int) const at ??:? [12] #5 Foam::smoothSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:? [12] #6 ? at ??:? [12] #7 ? at ??:? [12] #8 ? at ??:? [12] #9 ? at ??:? [12] #10 ? at ??:? [12] #11 __libc_start_main in "/usr/lib64/libc.so.6" [12] #12 ? at ??:? [newtont38:93775] *** Process received signal *** [newtont38:93775] Signal: Floating point exception (8) [newtont38:93775] Signal code: (6) [newtont38:93775] Failing at address: 0x64500016e4f [newtont38:93775] [ 0] /usr/lib64/libc.so.6(+0x35670)[0x7faad0986670] [newtont38:93775] [ 1] /usr/lib64/libc.so.6(gsignal+0x37)[0x7faad09865f7] [newtont38:93775] [ 2] /usr/lib64/libc.so.6(+0x35670)[0x7faad0986670] [newtont38:93775] [ 3] /softs/software/OpenFOAM/3.0.0foss2016a/OpenFOAM3.0.0/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZN4Foam22symGaussSeidelSmoother6smoothERKNS_4wordERNS_5FieldIdEERKNS_9lduMatrixERKS5_RKNS_10FieldFieldIS4_dEERKNS_8UPtrListIKNS_17lduInterfaceFieldEEEhi+0x2e7)[0x7faad19699b7] [newtont38:93775] [ 4] /softs/software/OpenFOAM/3.0.0foss2016a/OpenFOAM3.0.0/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam22symGaussSeidelSmoother6smoothERNS_5FieldIdEERKS2_hi+0x2a)[0x7faad1969daa] [newtont38:93775] [ 5] /softs/software/OpenFOAM/3.0.0foss2016a/OpenFOAM3.0.0/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam12smoothSolver5solveERNS_5FieldIdEERKS2_h+0x36b)[0x7faad1962afb] [newtont38:93775] [ 6] icoFoam[0x437307] [newtont38:93775] [ 7] icoFoam[0x45bba2] [newtont38:93775] [ 8] icoFoam[0x45bed5] [newtont38:93775] [ 9] icoFoam[0x45c0cb] [newtont38:93775] [10] icoFoam[0x41e2a5] [newtont38:93775] [11] /usr/lib64/libc.so.6(__libc_start_main+0xf5)[0x7faad0972b15] [newtont38:93775] [12] icoFoam[0x41f0a5] [newtont38:93775] *** End of error message *** Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 PISO: Operating solver in PISO mode Reading transportProperties Reading field p Reading field U Reading/calculating face flux field phi Starting time loop Time = 1e07 Courant Number mean: 0 max: 0 smoothSolver: Solving for Ux, Initial residual = 0, Final residual = 0, No Iterations 0 smoothSolver: Solving for Uy, Initial residual = 0, Final residual = 0, No Iterations 0 smoothSolver: Solving for Uz, Initial residual = 1, Final residual = 0.00431533, No Iterations 1000 DICPCG: Solving for p, Initial residual = 1, Final residual = 9.94297e07, No Iterations 170 DICPCG: Solving for p, Initial residual = 4.97148e07, Final residual = 4.97148e07, No Iterations 0 DICPCG: Solving for p, Initial residual = 4.97148e07, Final residual = 4.97148e07, No Iterations 0 time step continuity errors : sum local = 6.20264e14, global = 5.75653e16, cumulative = 5.75653e16 DICPCG: Solving for p, Initial residual = 0.00071311, Final residual = 9.95584e07, No Iterations 119 DICPCG: Solving for p, Initial residual = 9.96291e07, Final residual = 9.96291e07, No Iterations 0 DICPCG: Solving for p, Initial residual = 9.96291e07, Final residual = 9.96291e07, No Iterations 0 time step continuity errors : sum local = 1.24125e13, global = 2.93483e15, cumulative = 3.51048e15 ExecutionTime = 0.95 s ClockTime = 2 s Time = 2e07 Courant Number mean: 3.12606e08 max: 2.42506e07 smoothSolver: Solving for Ux, Initial residual = 0.312894, Final residual = 0.0162492, No Iterations 1000 smoothSolver: Solving for Uy, Initial residual = 0.312584, Final residual = 0.0157778, No Iterations 1000 smoothSolver: Solving for Uz, Initial residual = 0.998651, Final residual = 0.000700336, No Iterations 1000 DICPCG: Solving for p, Initial residual = 1.92216e05, Final residual = 9.82794e07, No Iterations 95 DICPCG: Solving for p, Initial residual = 9.82805e07, Final residual = 9.82805e07, No Iterations 0 DICPCG: Solving for p, Initial residual = 9.82805e07, Final residual = 9.82805e07, No Iterations 0 time step continuity errors : sum local = 1.22442e13, global = 9.4954e15, cumulative = 1.30059e14 DICPCG: Solving for p, Initial residual = 5.43799e06, Final residual = 9.1311e07, No Iterations 18 DICPCG: Solving for p, Initial residual = 9.13111e07, Final residual = 9.13111e07, No Iterations 0 DICPCG: Solving for p, Initial residual = 9.13111e07, Final residual = 9.13111e07, No Iterations 0 time step continuity errors : sum local = 1.13759e13, global = 7.81266e15, cumulative = 5.19322e15 ExecutionTime = 2.71 s ClockTime = 3 s ......... ......... ......... Time = 2e06 Courant Number mean: 5.93205e07 max: 1.04163e06 smoothSolver: Solving for Ux, Initial residual = 0.039176, Final residual = 0.0305109, No Iterations 1000 smoothSolver: Solving for Uy, Initial residual = 0.039092, Final residual = 0.031189, No Iterations 1000 smoothSolver: Solving for Uz, Initial residual = 0.996365, Final residual = 0.00701699, No Iterations 1000 DICPCG: Solving for p, Initial residual = 2.24311e05, Final residual = 9.96784e07, No Iterations 21 DICPCG: Solving for p, Initial residual = 9.9677e07, Final residual = 9.9677e07, No Iterations 0 DICPCG: Solving for p, Initial residual = 9.9677e07, Final residual = 9.9677e07, No Iterations 0 time step continuity errors : sum local = 1.24186e13, global = 1.07502e15, cumulative = 1.70953e13 DICPCG: Solving for p, Initial residual = 2.24562e05, Final residual = 9.90915e07, No Iterations 21 DICPCG: Solving for p, Initial residual = 9.90929e07, Final residual = 9.90929e07, No Iterations 0 DICPCG: Solving for p, Initial residual = 9.90929e07, Final residual = 9.90929e07, No Iterations 0 time step continuity errors : sum local = 1.23455e13, global = 5.12061e15, cumulative = 1.76073e13 ExecutionTime = 34.06 s ClockTime = 35 s U2e6.png Last edited by kindle; December 3, 2016 at 07:58. Reason: Clarify the problem 

December 2, 2016, 12:45 
For more info

#2 
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Settings for elbow
fvSchemes.elbow.txt fvSolution.elbow.txt Settings which works with structured grid, found out a little different with cavity though ... fvSchemes.txt fvSolution.txt And I'm using : OpenFOAM/3.0.0foss2016a The mesh I created with Pointwise. Here is the Tjunction I am working on. T.png I tried a structured mesh like butterfly.png as the last one posted without the fillet. But I get div(U) of order 0.1 with my velocity at entry of order 1m/s and the mean area that doesn't satisfy continuity is at the sharp corner (I have two entry [perpendicular between them] and one exit). Without the junction, I get div(U) of order 1.0e3. So might be the sharp corner ? To create a fillet the most natural way I can think of is rotating the mesh (typeH just to show the idea) by the white axe. Thus nonstructured ! 

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icofoam, unstructured mesh 
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