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Problem about divergence problem in k-epsilon model

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Old   October 20, 2016, 08:04
Default Problem about divergence problem in k-epsilon model
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Fujiang Yu
Join Date: Jan 2014
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Dear all,

I'm planning to run a very simple 0.09*0.03*0.03 rectangle case, which gets an inlet of 10m/s from left face and outlet from right face.
The mesh is 90*30*30, and the turbulence model has been chosen to k-epsilon model.

However, every time I try to run the steady case with simpleFoam, it got diverged pretty fast. Most wired thing is that the more I decrease the time interval, the more fast it got diverged. With similar time interval, laminar case could easily get converged.
So guys, what would you think would be the reason for it. Is it possible because that I didn't dense the wall layer part, or something else

time step continuity errors : sum local = 4.69681e+98, global = -1.2885e+87, cumulative = -1.2885e+87
#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3 double 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<double>::solveSegregated(Foam::dict ionary const&) at ??:?
#6 Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
#7 Foam::fvMatrix<double>::solve() at ??:?
#8 Foam::SolverPerformance<double> Foam::solve<double>(Foam::tmp<Foam::fvMatrix<doubl e> > const&) at ??:?
#9 Foam::RASModels::kEpsilon<Foam::IncompressibleTurb ulenceModel<Foam::transportModel> >::correct() at ??:?
#10 ? at ??:?
#11 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#12 ? at ??:?
Floating point exception (core dumped)

k setting
internalField uniform 0.0375;

boundaryField
{
inlet
{
type fixedValue;
value uniform 0.0375;
}
outlet
{
type zeroGradient;
}
wall
{
type kqRWallFunction;
value uniform 0.0375;
}
}

epsilon setting
internalField uniform 14.855;

boundaryField
{
inlet
{
type fixedValue;
value uniform 14.855;
}
outlet
{
type zeroGradient;
}
wall
{
type epsilonWallFunction;
value uniform 14.855;
}
}
nut setting
internalField uniform 0;

boundaryField
{
inlet
{
type calculated;
value uniform 0;
}
outlet
{
type calculated;
value uniform 0;
}
wall
{
type nutkWallFunction;
value uniform 0;
}
}

Thanks and look forward to any reply
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Tags
k-epsilon model, simplefoam convergence


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