# simpleFoam "Floating point exception" issues

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August 10, 2021, 07:50
simpleFoam "Floating point exception" issues
#1
New Member

Jo
Join Date: Aug 2021
Posts: 3
Rep Power: 2
Hi, I'm a student studying on CFD these days, and I've spent an amount of time trying to solve an error.

I'll upload the full log file, so you might be able to check if you need it.

------Error Message Begins--------

Time = 2.96

DILUPBiCG: Solving for Ux, Initial residual = 0.388057, Final residual = 0.0111543, No Iterations 61
DILUPBiCG: Solving for Uy, Initial residual = 0.461342, Final residual = 0.00384607, No Iterations 57
DICPCG: Solving for p, Initial residual = 0.999999, Final residual = 129029, No Iterations 1000
time step continuity errors : sum local = 4.41946e+103, global = -2.9527e+96, cumulative = -2.9527e+96
smoothSolver: Solving for nuTilda, Initial residual = 5.41952e-07, Final residual = 3.47411e-12, No Iterations 2
bounding nuTilda, min: -7.70956e+07 max: 1.53879e+09 average: 1.69814e+06
ExecutionTime = 1.5 s ClockTime = 1 s

Time = 3

#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#3 Foam::scalarProduct<double, double>::type Foam::sumProd<double>(Foam::UList<double> const&, Foam::UList<double> const&) at ??:?
#4 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#5 Foam::fvMatrix<Foam::Vector<double> >::solveSegregated(Foam::dictionary const&) at ??:?
#6 Foam::fvMatrix<Foam::Vector<double> >::solveSegregatedOrCoupled(Foam::dictionary const&) at ??:?
#7 Foam::fvMesh::solve(Foam::fvMatrix<Foam::Vector<do uble> >&, Foam::dictionary const&) const at ??:?
#8 ? at ??:?
#9 __libc_start_main in /lib/x86_64-linux-gnu/libc.so.6
#10 ? at ??:?
Floating point exception

------Error Message Ends--------

I could check the pressure value not converging.

I've met this error before, and I was able to solve it by changing the solvers.
However, this time the error is not able to solve through these solvers.

I will add the files used for my CFD, however just for explanation the solvers that used to solve this problem were

solvers
{
p
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0 .1;
}

U
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-08;
relTol 0.1;
}

nuTilda
{
solver smoothSolver;
smoother DILU;
nSweeps 2;
tolerance 1e-08;
relTol 0.1;
}
}

But it doesn't seem to help anymore.

p.s. I couldn't upload my files due to file size limit. Instead if you need, you would be able to check the files that I used through the link following.

Thank you very much for your help
Attached Files
 log.txt (48.6 KB, 0 views)

 August 10, 2021, 07:52 #2 Senior Member     Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 727 Rep Power: 13 Lok what happens with your pressuer: Code: ```DICPCG: Solving for p, Initial residual = 0.999999, Final residual = 129029, No Iterations 1000 time step continuity errors : sum local = 4.41946e+103, global = -2.9527e+96, cumulative = -2.9527e+96``` Mostly, b.c. are wrong in such cases. hesed likes this. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

August 10, 2021, 22:08
#3
New Member

Jo
Join Date: Aug 2021
Posts: 3
Rep Power: 2
Quote:
 Originally Posted by piu58 Lok what happens with your pressuer: Code: ```DICPCG: Solving for p, Initial residual = 0.999999, Final residual = 129029, No Iterations 1000 time step continuity errors : sum local = 4.41946e+103, global = -2.9527e+96, cumulative = -2.9527e+96``` Mostly, b.c. are wrong in such cases.
Thank you Mr. Pilz. I should check my b.c. and try again.

Have a nice day!

 August 10, 2021, 22:24 #4 New Member   Jo Join Date: Aug 2021 Posts: 3 Rep Power: 2 I was able to solve the problem by increasing the "internalField", "freestreamValue" values of the "nuTilda" file. I am not sure how this worked out, but seems like it is related with the "SpalartAllmaras" RAS model. Hope this might help anyone else having the same problem with me ==(edit)== Found out Mr. Pilz was correct! The B.C. for nuTilda was wrong. Checking out about Spalar Allmaras model at Wikipedia might help https://en.wikipedia.org/wiki/Spalar...rbulence_model Last edited by hesed; August 10, 2021 at 23:14. Reason: adding information!

 Tags floating point exception, simplefoam