[Zeallt]

Hi everyone,

I'm a newbie in OpenFOAM, and I just started using interFoam to simulate the flow in/out of a tank at several flow rates.

I used adjustTimeStep, maxCo=0.5, maxAlphaCo=0.25;
these two Courant numbers are always met in the whole simulation, however, the deltaT just keep going smaller, then boom!

Courant Number mean: 9.74622e-05 max: 0.514668
Interface Courant Number mean: 4.23283e-05 max: 0.140708
deltaT = 9.80635e-14
Time = 2.63702354776843

[1] #0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam222/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[1] #1  Foam::sigFpe::sigHandler(int) in "/opt/openfoam222/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
[1] #2   in "/lib/x86_64-linux-gnu/libc.so.6"
[1] #3  void Foam::MULES::limiter<Foam::geometricOneField, Foam::zeroField, Foam::zeroField>(Foam::Field<double>&, Foam::geometricOneField const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::zeroField const&, Foam::zeroField const&, double, double, int) in "/opt/openfoam222/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
[1] #4  void Foam::MULES::limit<Foam::geometricOneField, Foam::zeroField, Foam::zeroField>(Foam::geometricOneField const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh>&, Foam::zeroField const&, Foam::zeroField const&, double, double, int, bool) in "/opt/openfoam222/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
[1] #5  Foam::MULES::explicitSolve(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh>&, double, double) in "/opt/openfoam222/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
[1] #6  
[1]  in "/opt/openfoam222/platforms/linux64GccDPOpt/bin/interFoam"
[1] #7  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
[1] #8  
[1]  in "/opt/openfoam222/platforms/linux64GccDPOpt/bin/interFoam"
[leecae2:24773] *** Process received signal ***
[leecae2:24773] Signal: Floating point exception (8)
[leecae2:24773] Signal code:  (-6)
[leecae2:24773] Failing at address: 0x3e8000060c5
[leecae2:24773] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x364a0) [0x7fca2e3b14a0]
[leecae2:24773] [ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x35) [0x7fca2e3b1425]
[leecae2:24773] [ 2] /lib/x86_64-linux-gnu/libc.so.6(+0x364a0) [0x7fca2e3b14a0]
[leecae2:24773] [ 3] /opt/openfoam222/platforms/linux64GccDPOpt/lib/libfiniteVolume.so(_ZN4Foam5MULES7limiterINS_17geometricOneFieldENS_9zeroFieldES3_EEvRNS_5FieldIdEERKT_RKNS_14GeometricFieldIdNS_12fvPatchFieldENS_7volMeshEEERKNSA_IdNS_13fvsPatchFieldENS_11surfaceMeshEEESK_RKT0_RKT1_ddi+0xe59) [0x7fca31047939]
[leecae2:24773] [ 4] /opt/openfoam222/platforms/linux64GccDPOpt/lib/libfiniteVolume.so(_ZN4Foam5MULES5limitINS_17geometricOneFieldENS_9zeroFieldES3_EEvRKT_RKNS_14GeometricFieldIdNS_12fvPatchFieldENS_7volMeshEEERKNS7_IdNS_13fvsPatchFieldENS_11surfaceMeshEEERSF_RKT0_RKT1_ddib+0x244) [0x7fca3104a9d4]
[leecae2:24773] [ 5] /opt/openfoam222/platforms/linux64GccDPOpt/lib/libfiniteVolume.so(_ZN4Foam5MULES13explicitSolveERNS_14GeometricFieldIdNS_12fvPatchFieldENS_7volMeshEEERKNS1_IdNS_13fvsPatchFieldENS_11surfaceMeshEEERS8_dd+0x79) [0x7fca3103a329]
[leecae2:24773] [ 6] interFoam() [0x424fd9]
[leecae2:24773] [ 7] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xed) [0x7fca2e39c76d]
[leecae2:24773] [ 8] interFoam() [0x42c06d]
[leecae2:24773] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 1 with PID 24773 on node leecae2 exited on signal 8 (Floating point exception).

First, I doubted if it's giving me some weirdly large velocities, but I checked the results for the last few time steps, everything seems reasonable. And this was ran with 8 processors, when I switched to another computer and ran with 2 processors(re-decompose), it's ok.

Can anybody help me figure out how to solve the problem, many thanks!

Lee

[Artur]

Hi Lee,

Have you found a solution to your problem? I have ran into something similar with my recent simulation...

Peace,

Artur

[Zeallt]

Hi Auther,

I haven't find any solutions.

But I think it might has something to do with the mesh, maybe there's a few tiny cells (smallest in volume, or highly twisted) at those high velocity regions (e.g. a turn or sudden expansion), although the maxCo is satisfied at each time step, but still the calculated velocities keep increasing, eventually blows up the time step.

That's my guess, and actually I did a checkMesh everytime before I run the solver, it gets 'Mesh OK' under the default criteria then I'll run it. Maybe try to further lower the Mesh non-orthogonality and skewness, not for sure

Lee

[Artur]

Thanks for summing up your conclusions. My issue is not mesh related, it seems to have more to do with the numerical setup. I'll keep looking.

Good luck with your simulation,

A