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-   -   Moving Mesh (http://www.cfd-online.com/Forums/openfoam/102161-moving-mesh.html)

samiam1000 May 24, 2012 02:48

Moving Mesh
 
Dear All,

I am trying to run a moving-mesh problem when I give the moveDynamicMesh command, I get this error:

Quote:

lab@lab-laptop:~/Documenti/cases_OF/OF_case18_moving_door/moving_door_0$ moveDynamicMesh
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / 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 : moveDynamicMesh
Date : May 24 2012
Time : 10:00:10
Host : "lab-laptop"
PID : 3028
Case : /home/lab/Documenti/cases_OF/OF_case18_moving_door/moving_door_0
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Disallowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Selecting dynamicFvMesh dynamicMotionSolverFvMesh
Selecting motion solver: displacementLaplacian
Selecting motion diffusion: inverseDistance
Time = 5e-06
GAMG: Solving for cellDisplacementx, Initial residual = 0, Final residual = 0, No Iterations 0
GAMG: Solving for cellDisplacementy, Initial residual = 0, Final residual = 0, No Iterations 0
GAMG: Solving for cellDisplacementz, Initial residual = 1, Final residual = 8.56595e-07, No Iterations 9
Point usage OK.
Upper triangular ordering OK.
Topological cell zip-up check OK.
Face vertices OK.
Face-face connectivity OK.
Mesh topology OK.
Boundary openness (-3.45182e-17 2.95949e-17 3.53759e-17) OK.
***High aspect ratio cells found, Max aspect ratio: 1.41654e+198, number of cells 4786
Minumum face area = 4.60908e-06. Maximum face area = 0.0398707. Face area magnitudes OK.
Min volume = 1.33333e-300. Max volume = 0.00143918. Total volume = 5.5607. Cell volumes OK.
Mesh non-orthogonality Max: 179.655 average: 62.4743
*Number of severely non-orthogonal faces: 34479.
***Number of non-orthogonality errors: 9301.
***Error in face pyramids: 19112 faces are incorrectly oriented.
***Max skewness = 2617.13, 2542 highly skew faces detected which may impair the quality of the results
Failed 4 mesh geometry checks.
Failed 1 mesh checks.
ExecutionTime = 1.6 s ClockTime = 2 s

Time = 1e-05
#0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#2 in "/lib/libc.so.6"
#3 void Foam::mag<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh>(Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh>&, Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#4 Foam::tmp<Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> > Foam::mag<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh>(Foam::GeometricField<Foam::Vect or<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#5 Foam::fv::limitedSnGrad<Foam::Vector<double> >::correction(Foam::GeometricField<Foam::Vector<do uble>, Foam::fvPatchField, Foam::volMesh> const&) const in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#6 Foam::fv::gaussLaplacianScheme<Foam::Vector<double >, double>::fvmLaplacian(Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#7 Foam::tmp<Foam::fvMatrix<Foam::Vector<double> > > Foam::fvm::laplacian<Foam::Vector<double>, double>(Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::word const&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfvMotionSolvers.so"
#8 Foam::tmp<Foam::fvMatrix<Foam::Vector<double> > > Foam::fvm::laplacian<Foam::Vector<double>, double>(Foam::tmp<Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> > const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::word const&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfvMotionSolvers.so"
#9 Foam::displacementLaplacianFvMotionSolver::solve() in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfvMotionSolvers.so"
#10 Foam::motionSolver::newPoints() in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libdynamicMesh.so"
#11 Foam::dynamicMotionSolverFvMesh::update() in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libdynamicFvMesh.so"
#12
in "/opt/openfoam210/platforms/linux64GccDPOpt/bin/moveDynamicMesh"
#13 __libc_start_main in "/lib/libc.so.6"
#14
in "/opt/openfoam210/platforms/linux64GccDPOpt/bin/moveDynamicMesh"
Floating point exception

Is this a problem with the mesh? Which are the steps that may help to get a good result?

Thanks a lot,

Samuele

SirWombat May 25, 2012 02:48

Hi Samuele,

there are these three asterisks "***" which tell you, that there's something terribly wrong. So your mesh features the following bad cells:

4786 High aspect ratio cells
34479 severly non-othogonal faces
19112 incorretly oriented faces
2542 highly skewed faces

so YES, this is most probably a problem with the mesh an you will need to increase your mesh quality!

I suppose you are using snappyHexMesh, so then it's a good start to find the problematic cells by running "checkMesh" after you created your mesh. checkMesh will create "sets" of those bad cells und you can view them in paraview/paraFoam.

A good start for snappyHexMesh is to switch off all quality controls, and then have a look at the bad cells with checkMesh and paraview. After that you may slowly try to rise the quality parameters in SHM und see how that effects your mesh.
I suggest to do that on a tiny part of your mesh, e.g. by using an appropriate blockMeshDict

Greets,
Jan

Giuliano69 May 28, 2012 05:59

May I ask where can be found "documented" examples of moving mash, to learn how to configure and deal with them ?

kid May 28, 2012 06:34

Use "moveDynamicMesh --help"
This is the best help. Also try to redo any tutorial on moveDynamicMesh.

eysteinn May 30, 2012 08:22

Quote:

Originally Posted by Giuliano69 (Post 363409)
May I ask where can be found "documented" examples of moving mash, to learn how to configure and deal with them ?

Hi Giuliano,

There are a few tutorials where you can read about the different settings for the mesh motion, i.e. here, here, here and here.

More tutorials can be found here by changing the year from 2007 to 2011.

Hope this helps :)
Eysteinn


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