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-   -   URGENT! Error with icoFoam (http://www.cfd-online.com/Forums/openfoam-solving/107833-urgent-error-icofoam.html)

gara1988 October 7, 2012 14:52

URGENT! Error with icoFoam
 
Hello, I did a mesh around an airfoil. BlockMesh has gone well.

When I run icoFoam I have this error:


Starting time loop

Time = 0.001

Courant Number mean: 0.0568875 max: 7.3117e+297
#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::fvc::surfaceIntegrate<Foam::Vector<double> >(Foam::Field<Foam::Vector<double> >&, Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam210/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/openfoam210/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#5 Foam::tmp<Foam::GeometricField<Foam::Vector<double >, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div<Foam::Vector<double> >(Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#6 Foam::tmp<Foam::GeometricField<Foam::Vector<double >, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div<Foam::Vector<double> >(Foam::tmp<Foam::GeometricField<Foam::Vector<doub le>, Foam::fvsPatchField, Foam::surfaceMesh> > const&) in "/opt/openfoam210/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#7 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"
#8
in "/opt/openfoam210/platforms/linux64GccDPOpt/bin/icoFoam"
#9
in "/opt/openfoam210/platforms/linux64GccDPOpt/bin/icoFoam"
#10
in "/opt/openfoam210/platforms/linux64GccDPOpt/bin/icoFoam"
#11
in "/opt/openfoam210/platforms/linux64GccDPOpt/bin/icoFoam"
#12 __libc_start_main in "/lib/libc.so.6"
#13
in "/opt/openfoam210/platforms/linux64GccDPOpt/bin/icoFoam"
Floating point exception

Is Courant number the problem? But max courant number is terrible high!!

Thanks for the reply!

Bye
Mattia

gara1988 October 7, 2012 15:06

I have seen tha,t in other post, Courant number is indicated as the problem. Here I have C number equal to 7.3117e+297, it is terrible high. I don't know why it is so high.

wyldckat October 7, 2012 15:34

Greetings Mattia,

Since it's icoFoam, there are at least two reasons this error occurs:
  1. The mesh might be damaged. To check this, run:
    Code:

    checkMesh
  2. You didn't indicate anything about how you configured parameters in "controlDict". Which probably means that you changed nothing or very little in it. Therefore, I suggest you go read the User Guide once again, namely this section: 2.1.5 Increasing the mesh resolution
Best regards,
Bruno

gara1988 October 7, 2012 15:42

Thanks Bruno for the reply.

When I run checkMesh I have "failed 3 mesh checks".
What means that the mesh is damaged?

Best regards
Mattia.

wyldckat October 7, 2012 15:48

I meant "damaged" in a generic way.
As you've seen, it failed 3 mesh checks, which means that there seems to be something wrong with the mesh... which could be considered as "damaged". ;)

You'll have to diagnose yourself what checkMesh tells you is wrong and fix "blockMeshDict" so that checkMesh no longer complains.

Tobi October 7, 2012 17:07

Hi Mattia,

which error messages do you get? Some messages are not as critical as other.
And set your start time to 1e-6 or 1e-7 for starting your solution.

But first check your mesh again. Like bruno said, you have to improve your mesh quality if the errors are critical errors

alberto October 8, 2012 02:33

Hints:

- the solution fails when calculating a Laplacian, and the mesh fails 3 tests, so you should report what tests it fails (or the whole output of checkMesh), and most likely re-mesh until those errors disappear. Tweaking the solver is unlikely to help.

- Please, next time don't write your question is "urgent". All questions are "urgent" in the same way, and trying to get more attention usually results in the opposite. :D

gara1988 October 8, 2012 03:36

Ok. I'm sorry Alberto.

Thanks all for the reply!

Best regards.
Mattia

gara1988 October 8, 2012 03:59

How can I undestand where it's the problem of mesh? For example what is the face that has zero area.

Sorry but I'm studying openfoam from a week.


Checking geometry...
Overall domain bounding box (-5 -5 0) (15 5 0)
Mesh (non-empty, non-wedge) directions (1 1 0)
Mesh (non-empty) directions (1 1 0)
All edges aligned with or perpendicular to non-empty directions.
Boundary openness (0 0 2.45443e-16) OK.
Max cell openness = 9.72873e-16 OK.
Max aspect ratio = 0 OK.
***Zero or negative face area detected. Minimum area: 0
<<Writing 28416 zero area faces to set zeroAreaFaces
Min volume = 1.33333e-300. Max volume = 2e-300. Total volume = 3.95333e-296. Cell volumes OK.
Mesh non-orthogonality Max: 90 average: 90
***Number of non-orthogonality errors: 39300.
<<Writing 39300 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
***Max skewness = 706.342, 42336 highly skew faces detected which may impair the quality of the results
<<Writing 42336 skew faces to set skewFaces
Coupled point location match (average 0) OK.

Failed 3 mesh checks.

End


Thanks.
Best regards.
Mattia

gara1988 October 8, 2012 08:27

With checkMesh and doing the mesh better I solve the problem. Thanks a lot.

Mattia


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