CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

Help with solving floating point exception crash.

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   March 24, 2014, 09:02
Exclamation Help with solving floating point exception crash. [SOLVED]
New Member
Join Date: Sep 2013
Posts: 8
Rep Power: 4
rendagar is on a distinguished road

Does someone have any idea what is casing the crash I'm experiencing when using chtMultiRegionFoam on a case I have build using OpenFOAM 2.3.0 (using openSuse 13.1). I know the error is a floating point exception (which is caused by dividing by 0 or some other invalid math operation) however I'm unable to find the root cause. It error I have is the following:

Solving for fluid region airEnclosure
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 1, Final residual = 1.3008103e-11, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 1, Final residual = 1.2358456e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 1, Final residual = 1.7628265e-11, No Iterations 2
DILUPBiCG:  Solving for h, Initial residual = 1, Final residual = 5.3365854e-11, No Iterations 2
Min/max T:300 350
#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::sigFpe::sigHandler(int) at ??:?
#2   in "/lib64/"
#3  Foam::fanFvPatchField<double>::calcFanJump() at ??:?
#4  Foam::fanFvPatchField<double>::updateCoeffs() at ??:?
#5  Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>::GeometricBoundaryField::updateCoeffs() at ??:?
#6  Foam::fvMatrix<double>::fvMatrix(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::dimensionSet const&) at ??:?
#7  Foam::fv::EulerDdtScheme<double>::fvmDdt(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) at ??:?
#8  Foam::tmp<Foam::fvMatrix<double> > Foam::fvm::ddt<double>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) at ??:?
 at ??:?
#10  __libc_start_main in "/lib64/"
 at /home/abuild/rpmbuild/BUILD/glibc-2.18/csu/../sysdeps/x86_64/start.S:125
Floating point exception
and it is generated by the GAMG solver trying to solve for p_rgh when including a fan type boundary condition. The settings for the simulation where taken from a similar case I have made which runs without a problem. Both cases are based on the multiRegionHeater tutorial.

The idea behind the simulation is to simulate forced air flow and heat conduction inside an enclosure.

Below is a more detailed description of the work flow I use to generate the error.

> ./Allrun
> Running blockMesh on /mnt/WIN/51640_2060/05_OpenFoam/failCase
> Running topoSet on /mnt/WIN/51640_2060/05_OpenFoam/failCase
> Running splitMeshRegions on /mnt/WIN/51640_2060/05_OpenFoam/failCase
> Running createBaffles on /mnt/WIN/51640_2060/05_OpenFoam/failCase
There are no warmings in the log files created except for createBaffles which reports

--> FOAM Warning :
    From function createBaffles
    in file createBaffles.C at line 773
    Setting field on boundary faces to zero.
You might have to edit these fields.
what I do not believe to be a problem.

However when I try to run chtMultiRegionFoam I get the floating point exception mentioned above.

When I comment out the fan boundary condition from system/airEnclosure/createBafflesDict the simulation runs without a problem (however also without the forced air flow I want to include) so I know there is a problem somewhere there.

I have tried moving the simulation domain to just positive axis, changed the shape and location of the fan boundary, increasing the number of cells in the domain and trying to use a staggered grid (actually the staggered grid was the initial case and I was hoping it was the cause of the error, no luck there though) and investigated changing the fan boundary condition. Nothing so far has solved the error.

I have added 2 cases for anyone to investigate.

failCase --> This fails like described above.
fanCase --> Similar setup (no heat source) but runs without a problem. Proving the simulation is possible.

The main differences between the two cases above is that the failCase includes a airOutside region around the enclosure. Also the enclosure is created using topoSet instead of it being the entire simulation domain as in the fanCase case.

If anyone could spare some time to investigate the error it would be very much appreciated. I've been stuck on this for some time now.

Attached Files
File Type: gz failCase.tar.gz (59.3 KB, 1 views)
File Type: gz fanCase.tar.gz (12.8 KB, 2 views)

Last edited by rendagar; March 26, 2014 at 08:35. Reason: Problem solved
rendagar is offline   Reply With Quote

Old   March 26, 2014, 08:34
Lightbulb Solved yet not understood
New Member
Join Date: Sep 2013
Posts: 8
Rep Power: 4
rendagar is on a distinguished road
I managed to solve the problem. Don't quite understand it yet but perhaps some investigation into the fan boundary condition or the chtMultiregionFoam solver will prove insightful.

The problem is solved by removing the fan type boundary condition on fan_half0 and fan_half1 in 0/airEnclosure/p and replacing it with a cyclic one (or probably anything, they don't seem to affect the simulation). The fan_half* conditions in 0/airEnclosure/p_rgh remain the same i.e.

    type            fan;
    patchType       cyclic;
    jump            uniform 0;
    value           uniform 0;
    jumpTable       polynomial 1 ( ( 100 0 ) );
    type            fan;
    patchType       cyclic;
    value           uniform 0;
Now there is no crash when running chtMultiRegionFoam and the initial results show there is both forced air flow and heating of the air. Apparently the values in p do not influence the results of this solver (or at least not noticeably) but they are capable of crashing the solver.

Now on to refining the boundary conditions and solvers e.t.c.

Last edited by rendagar; March 26, 2014 at 08:35. Reason: Found the answer
rendagar is offline   Reply With Quote


chtmultiregionfoam, fan boundary condition, floating point exception

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
buoyantSimpleFoam and watertank Tobi OpenFOAM Running, Solving & CFD 48 December 26, 2014 09:49
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
problem with Min/max rho tH3f0rC3 OpenFOAM 7 February 23, 2013 06:37
Orifice Plate with a fully developed flow - Problems with convergence jonmec OpenFOAM Running, Solving & CFD 3 July 28, 2011 05:24
IcoFoam parallel woes msrinath80 OpenFOAM Running, Solving & CFD 9 July 22, 2007 02:58

All times are GMT -4. The time now is 18:31.