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-   -   Floating point exception error with small DeltaT (http://www.cfd-online.com/Forums/openfoam-solving/67955-floating-point-exception-error-small-deltat.html)

rassilon September 1, 2009 20:37

Floating point exception error with small DeltaT
 
Hi Foamers,

I have been going really well with foam over the past couple omf months until now.

I have recently imported a 3D model from a gambit .MSH file. I scaled it successfully using the -[scale] command, and initially it runs very well, until it reaches a point where it bombs out with a Floating point exception error.

-----

#0 Foam::error: printStack(Foam::Ostream&) in "/home/swervo/OpenFOAM/OpenFOAM-1.5/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/swervo/OpenFOAM/OpenFOAM-1.5/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted: [0xffffe400]
#3 Foam::Time::adjustDeltaT() in "/home/swervo/OpenFOAM/OpenFOAM-1.5/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 Foam::Time::setDeltaT(double) in "/home/swervo/OpenFOAM/OpenFOAM-1.5/lib/linuxGccDPOpt/libOpenFOAM.so"
#5 main in "/home/swervo/OpenFOAM/OpenFOAM-1.5/applications/bin/linuxGccDPOpt/interFoam"
#6 __libc_start_main in "/lib/libc.so.6"
#7 Foam::regIOobject::readIfModified() in "/home/swervo/OpenFOAM/OpenFOAM-1.5/applications/bin/linuxGccDPOpt/interFoam"
Floating point exception

-----

Is there anybody that can shed any light on this error?

The model is in the micro domain, solving using interFoam. I have had to use a very small timestep (1E-12) in previous models to reach a convergent solution, but this in itself hasn't thrown up this error in previous models. I notice that in lines #3 and #4 of the error message it mentions DeltaT, but doesn't give any further clues.

Does anybody have any ideas?


Cheers,


R

renyun0511 September 1, 2009 21:58

hi,
i have a worse result than yours ,the steps i used are as follows:
1.fluentMeshToFoam voim.msh -scale 1000
2.gedit constant/polyMesh/boundary &
3.gedit 0/* &
4.gedit constant/MRFZones &
5.gedit system/controlDict &
6.MRFSimpleFoam
but,it displayed :
cannot open file

file: /home/ry/OpenFOAM/ry-1.5/tutorials/MRFSimpleFoam/voim/system/controlDict at line 0.

From function regIOobject::readStream(const word&)
in file db/regIOobject/regIOobjectRead.C at line 66.
i don't know why? can you help me?
regards

renyun0511 September 1, 2009 21:59

before MRFSimpleFoam,i put $wmake in the console

chiven September 1, 2009 22:32

Quote:

Originally Posted by renyun0511 (Post 228184)
hi,
but,it displayed :
cannot open file

file: /home/ry/OpenFOAM/ry-1.5/tutorials/MRFSimpleFoam/voim/system/controlDict at line 0.

From function regIOobject::readStream(const word&)
in file db/regIOobject/regIOobjectRead.C at line 66.
i don't know why? can you help me?
regards

Please check the controlDict file, if there is no problem, delete it, then copy another from the corresponding tutorial cases and change it for your case.

Best regards,
Chiven

chiven September 1, 2009 22:39

Quote:

Originally Posted by rassilon (Post 228178)
Hi Foamers,


The model is in the micro domain, solving using interFoam. I have had to use a very small timestep (1E-12) in previous models to reach a convergent solution, but this in itself hasn't thrown up this error in previous models. I notice that in lines #3 and #4 of the error message it mentions DeltaT, but doesn't give any further clues.


R


The timestep is not the key point, please check the initialized fields, the discretization and linear solver settings.

Best regards,
Chiven

renyun0511 September 2, 2009 03:38

Dear chiven,
the controlDict file:
FoamFile

{

version 2.0;

format ascii;

class dictionary;

object controlDict;

}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //



application simpleFoam;



startFrom startTime;



startTime 0;



stopAt endTime;



endTime 500;



deltaT 1;



writeControl timeStep;



writeInterval 50;



purgeWrite 0;



writeFormat ascii;



writePrecision 6;



writeCompression uncompressed;



timeFormat general;



timePrecision 6;



runTimeModifiable yes;



// ************************************************** *********************** //
I don't know where is the problem.how to modify to it? would you like to help me?
regards,
jennifer

chiven September 2, 2009 03:49

Quote:

Originally Posted by renyun0511 (Post 228220)
Dear chiven,
application simpleFoam;

jennifer

try it

application MRFSimpleFoam;

and you had better reference to example case of MRFSimpleFoam.

best regards,
Chiven

renyun0511 September 2, 2009 03:57

Dear chiven,
I try to modify it ,but the result is all the same :cannot open file

file: /home/ry/OpenFOAM/ry-1.5/tutorials/MRFSimpleFoam/voim/system/controlDict at line 0.

From function regIOobject::readStream(const word&)
in file db/regIOobject/regIOobjectRead.C at line 66.

renyun0511 September 2, 2009 04:05

it puzzled me several days!

l_r_mcglashan September 2, 2009 05:19

If the solver can't find the file, then you're not running it from the correct directory. I see the case path is:

/home/ry/OpenFOAM/ry-1.5/tutorials/MRFSimpleFoam/voim/

Are you sure you're running MRFSimpleFoam from that directory?

PaMuelle September 2, 2009 05:42

I have a similar problem to yours, therefore I'll just post it here instead of starting a whole new thread.
I'm currently trying to get the MRFSimpleFoam example from the FoamWiki running. Since my iterations fail after ~7 equations I tried decreasing the timestep to get a Courant Number <1. Unfortunately, for that I have to choose a Step less than 1.8e-4. When I decrease the timestep to this number I get the following error:

#0 Foam::error: printStack(Foam::Ostream&) in "/home/mueller/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/mueller/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib/libc.so.6"
#3 void Foam::multiply<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<Foam::Tensor<d ouble>, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> const&) in "/home/mueller/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#4 Foam::tmp<Foam::GeometricField<Foam::Tensor<double >, Foam::fvPatchField, Foam::volMesh> > Foam: operator*<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<doub le, Foam::fvPatchField, Foam::volMesh> > const&, Foam::tmp<Foam::GeometricField<Foam::Tensor<double >, Foam::fvPatchField, Foam::volMesh> > const&) in "/home/mueller/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#5 Foam::incompressible::RASModels::kEpsilon::divDevR eff(Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) const in "/home/mueller/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#6 main in "/home/mueller/OpenFOAM/mueller-1.6/applications/bin/linux64GccDPOpt/MRFSimpleFoam"
#7 __libc_start_main in "/lib/libc.so.6"
#8 _start at /build/buildd/glibc-2.9/csu/../sysdeps/x86_64/elf/start.S:116
Floating point exception


I get the same error when I reduce the speed of the rotor to 10 ups and increase the timestep to 2.5e-3. Has anybody an idea why I can't decrease the timestep to an usable amount without getting a floating point exception?

Regards

chiven September 2, 2009 06:22

Quote:

Originally Posted by renyun0511 (Post 228223)
Dear chiven,
I try to modify it ,but the result is all the same :cannot open file

file: /home/ry/OpenFOAM/ry-1.5/tutorials/MRFSimpleFoam/voim/system/controlDict at line 0.

From function regIOobject::readStream(const word&)
in file db/regIOobject/regIOobjectRead.C at line 66.

How do you revise the controlDict? Do you use the editor of linux, like vi?

If you revise the file in windows platform, maybe it can not be opened.

Delete the OLD controlDict file and copy another from the example case of MRFSimple case.

Good luck.
Chiven

renyun0511 September 2, 2009 06:50

yes, I put the command on the console:gedit system/controlDict &
then,it displayed the information above, I changed the "application simpleFoam"to"application MRFSimpleFoam",saved it ,at last MRFSimpleFoam,but the result also is:cannot open file.

renyun0511 September 2, 2009 06:52

copy another from the example case of MRFSimple case?where is the MRFSimple example case?

chiven September 2, 2009 06:53

Quote:

Originally Posted by renyun0511 (Post 228252)
yes, I put the command on the console:gedit system/controlDict &
then,it displayed the information above, I changed the "application simpleFoam"to"application MRFSimpleFoam",saved it ,at last MRFSimpleFoam,but the result also is:cannot open file.


it is interesting. But i have no idea.

best regards,
Chiven

renyun0511 September 2, 2009 06:57

thank all the same!

regards,
jennifer

chiven September 2, 2009 07:01

Quote:

Originally Posted by renyun0511 (Post 228253)
copy another from the example case of MRFSimple case?where is the MRFSimple example case?


you can try to run the case

OpenFOAM/OpenFOAM-1.5/tutorials/MRFSimpleFoam/mixerVessel2D

and then do the calculation of yourself.

best regards,
Chiven

renyun0511 September 2, 2009 07:15

how to do the calculation of myself?

chiven September 2, 2009 07:23

Quote:

Originally Posted by renyun0511 (Post 228258)
how to do the calculation of myself?


reference to the user guide

http://www.opencfd.co.uk/openfoam/doc/user.html

enjoy,
chiven

renyun0511 September 2, 2009 07:39

thank you, chiven!
I sent a email to you just now,it detailed all the steps i adopt,hope for your guidance!


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