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Nut generating a floating point exception

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Old   May 17, 2018, 23:11
Post Nut generating a floating point exception
  #1
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Roberto Vázquez
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Good evening,
I'm pretty new to OpenFOAM and CFD in general, so this may be a dumb question. I'm trying to simulate flow in a pipe with chtMultiRegionSimpleFoam, but when I run my case, I get the following message:
#0 Foam::error:: printStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) at ??:?
#4 Foam:: operator/(Foam::tmp<Foam::Field<double> > const&, Foam::UList<double> const&) at ??:?
#5 Foam::CompressibleTurbulenceModel<Foam::fluidTherm o>::nu(int) const at ??:?
#6 Foam::nutkWallFunctionFvPatchScalarField::calcNut( ) const at ??:?
#7 Foam::nutWallFunctionFvPatchScalarField::updateCoe ffs() at ??:?
#8 Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>::Boundary::evaluate() at ??:?
#9 Foam::RASModels::kEpsilon<Foam::EddyDiffusivity<Fo am::ThermalDiffusivity<Foam::CompressibleTurbulenc eModel<Foam::fluidThermo> > > >::correctNut() at ??:?
#10 ? at ??:?
#11 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#12 ? at ??:?Floating point exception (core dumped)


I've read other posts with similar errors, with replies saying that most likely k and epsilon have initial values of zero. Mine are very small, around 3e-6, but definitely not zero. I don't really know what to do when I don't get a FOAM fatal error, so any help would be appreciated .

Thank you all in advance!

Last edited by robvazdom; May 17, 2018 at 23:13. Reason: smileys in my text
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Old   June 19, 2018, 18:24
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Raunak Bardia
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I am facing the same issue while trying to run "reactingFoam". I understand that the error is being generated from the calcNut() function called from the boundary condition "nutkwallfunction".

Here is that function:
Code:
tmp<scalarField> nutkWallFunctionFvPatchScalarField::calcNut() const
{
    const label patchi = patch().index();

    const turbulenceModel& turbModel = db().lookupObject<turbulenceModel>
    (
        IOobject::groupName
        (
            turbulenceModel::propertiesName,
            internalField().group()
        )
    );

    const scalarField& y = turbModel.y()[patchi];
    const tmp<volScalarField> tk = turbModel.k();
    const volScalarField& k = tk();
    const tmp<scalarField> tnuw = turbModel.nu(patchi);
    const scalarField& nuw = tnuw();

    const scalar Cmu25 = pow025(Cmu_);

    tmp<scalarField> tnutw(new scalarField(patch().size(), 0.0));
    scalarField& nutw = tnutw.ref();

    forAll(nutw, facei)
    {
        label celli = patch().faceCells()[facei];

         scalar yPlus = Cmu25*y[facei]*sqrt(k[celli])/nuw[facei]; 

        if (yPlus > yPlusLam_)
        {
           nutw[facei] = nuw[facei]*(yPlus*kappa_/log(E_*yPlus) - 1.0);
        }
    }

    return tnutw;
}
The issue seems to generate from the highlighted line as the line#5 in the error mentioned by Roberto refers to nu(int). On tracking line#5, I ended up in the file: OpenFOAM-5.0/src/TurbulenceModels/compressible/CompressibleTurbulenceModel. The reference to the nu(int) function is on line #125. The function is:

Code:
//- Return the laminar viscosity on patchi
        virtual tmp<scalarField> nu(const label patchi) const
        {
            return
                this->transport_.mu(patchi)/this->rho_.boundaryField()[patchi];
        }
The error is with division, and this implies that my rhoField has a value of zero at the boundaryField. I have defined the density using icoPolynomial<8> format. Is the error related to this or am I missing something else? How can we resolve this error? I have attached my 0 directory files.

Help from the more experienced FOAMers will be really useful.
Attached Files
File Type: zip 0directory.zip (7.8 KB, 1 views)

Last edited by raunakbardia; June 19, 2018 at 18:52. Reason: Identifying the Code component separately.
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chtmultiregionsimplefoam, floating point error, nut, openfoam

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