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Courant number blowing up, non-orthogonal mesh? |
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October 21, 2013, 05:14 |
Courant number blowing up, non-orthogonal mesh?
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#1 |
Member
Olie
Join Date: Oct 2013
Posts: 51
Rep Power: 13 |
Hi,
I'm trying to run a case I created with a backward facing step geometry, using the k-epsilon turbulence model, RAS solver. I've created the mesh and when I run blockMesh it creates the mesh (which when I view in ParaView looks correct) but gives some warnings: Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Creating block mesh from "/home/olie/OpenFOAM/olie-2.2.1/run/tutorials/incompressible/pisoFoam/ras/bfstep/constant/polyMesh/blockMeshDict" Creating curved edges Creating topology blocks Creating topology patches Creating block mesh topology --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -0.666667 for face 0 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -0.666667 for face 1 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -0.666667 for face 2 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -0.666667 for face 3 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -0.666667 for face 4 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -0.666667 for face 5 --> FOAM Warning : From function blockMesh::createTopology(IOdictionary&) in file blockMesh/blockMeshTopology.C at line 255 negative volume block : 0, probably defined inside-out --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 0 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 1 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 2 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 3 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 4 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 5 --> FOAM Warning : From function blockMesh::createTopology(IOdictionary&) in file blockMesh/blockMeshTopology.C at line 255 negative volume block : 1, probably defined inside-out --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 0 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 1 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 2 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 3 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 4 --> FOAM Warning : From function cellModel::mag(const labelList&, const pointField&) in file meshes/meshShapes/cellModel/cellModel.C at line 128 zero or negative pyramid volume: -2.66667 for face 5 --> FOAM Warning : From function blockMesh::createTopology(IOdictionary&) in file blockMesh/blockMeshTopology.C at line 255 negative volume block : 2, probably defined inside-out Check topology Basic statistics Number of internal faces : 2 Number of boundary faces : 14 Number of defined boundary faces : 14 Number of undefined boundary faces : 0 Checking patch -> block consistency Creating block offsets Creating merge list . Creating polyMesh from blockMesh Creating patches Creating cells Creating points with scale 1 Writing polyMesh ---------------- Mesh Information ---------------- boundingBox: (0 -2 0) (10 2 1) nPoints: 1942 nCells: 900 nFaces: 3670 nInternalFaces: 1730 ---------------- Patches ---------------- patch 0 (start: 1730 size: 10) name: inlet patch 1 (start: 1740 size: 20) name: outlet patch 2 (start: 1760 size: 110) name: fixedWalls patch 3 (start: 1870 size: 1800) name: frontAndBack End Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 Reading field p Reading field U Reading/calculating face flux field phi Selecting incompressible transport model Newtonian Selecting turbulence model type RASModel Selecting RAS turbulence model kEpsilon kEpsilonCoeffs { Cmu 0.09; C1 1.44; C2 1.92; sigmaEps 1.3; } Starting time loop Time = 0.001 Courant Number mean: 1.66667e+295 max: 1.5e+297 #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam221/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam221/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 in "/lib/x86_64-linux-gnu/libc.so.6" #3 void Foam::fvc::surfaceIntegrate<Foam::Vector<double> >(Foam::Field<Foam::Vector<double> >&, Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam221/platforms/linux64GccDPOpt/lib/libfiniteVolume.so" #4 Foam::tmp<Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::surfaceIntegrate<Foam::Vector<double> >(Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam221/platforms/linux64GccDPOpt/lib/libfiniteVolume.so" #5 at gaussDivSchemes.C:0 #6 Foam::fv::gaussDivScheme<Foam::Tensor<double> >::fvcDiv(Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam221/platforms/linux64GccDPOpt/lib/libfiniteVolume.so" #7 Foam::tmp<Foam::GeometricField<Foam::innerProduct<Foam::Vector<double>, Foam::Tensor<double> >::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div<Foam::Tensor<double> >(Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam221/platforms/linux64GccDPOpt/lib/libincompressibleTurbulenceModel.so" #8 Foam::incompressible::RASModels::kEpsilon::divDevReff(Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) const in "/opt/openfoam221/platforms/linux64GccDPOpt/lib/libincompressibleRASModels.so" #9 in "/opt/openfoam221/platforms/linux64GccDPOpt/bin/pisoFoam" #10 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #11 in "/opt/openfoam221/platforms/linux64GccDPOpt/bin/pisoFoam" Floating point exception (core dumped) I'd be very grateful if someone could help me out! Thanks, Olie |
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October 22, 2013, 11:43 |
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#2 |
Member
Eric Robertson
Join Date: Jul 2012
Posts: 95
Rep Power: 15 |
You need to re-mesh. Seems like you have some mesh quality issues- most specifically, inside-out cells.
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October 22, 2013, 15:22 |
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#3 | |
Member
Olie
Join Date: Oct 2013
Posts: 51
Rep Power: 13 |
Quote:
Now what exactly does that mean? Made a mistake with the way I defined blocks or something? Maybe the order of the vertices I give? Thanks for pointing that out. |
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October 22, 2013, 15:25 |
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#4 |
Member
Eric Robertson
Join Date: Jul 2012
Posts: 95
Rep Power: 15 |
That's what it seems like. You must also remember to follow the right hand rule when defining block faces etc.
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October 22, 2013, 16:57 |
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#5 | |
Member
Olie
Join Date: Oct 2013
Posts: 51
Rep Power: 13 |
Quote:
Thank you - I had a look at the way I'd defined blocks and faces and it would appear I didn't follow the RHR. So I've got it to run now, HOWEVER the mesh isn't using the same x-y-z coordinates as me it would seem. For example I have three blocks, which in blockMeshDict I've declared: Code:
blocks ( hex (11 12 4 3 8 9 1 0) (10 10 1) simpleGrading (1 1 1)//0 hex (12 13 5 4 9 10 2 1) (40 10 1) simpleGrading (1 1 1)//1 hex (14 15 7 6 12 13 5 4) (40 10 1) simpleGrading (1 1 1)//2 ); I.e. it's mixed up my mesh resolutions in the y & z directions - do you know why this is? Thanks for the help. Olie |
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October 22, 2013, 20:50 |
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#6 |
Senior Member
Alex
Join Date: Oct 2013
Posts: 337
Rep Power: 22 |
Hi odellar!
Read carefully the section 5.3 of the User Guide http://www.openfoam.org/docs/user/blockMesh.php. It's important to understand the use of the "local coordinate system" when you create your blocks and the difference between both local and global coordinate systems, which is what you see in paraview. cheers. zfaraday
__________________
Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in! |
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