swahono |
December 6, 2010 20:37 |
simpleFoam Blows up with Parabolic Inlet Pipe Flow
2 Attachment(s)
Hi All,
I am simulating a pipe with sudden expansion with a parabolic inlet velocity using simpleFoam .
The simulation started with laminar for 2000 iterations (residuals flat off after this) - solution attached.
Quote:
Centreline Inlet Velocity is 0.178 m/s. Re_D=40,750.
GroovyBC was used to set the parabolic inlet velocity profile.
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Then I restarted the simulation using RNGKEpsilon model.
The simulation crashed after 2 iterations! Consistently.
Error message indicate divide by zero problem for k and epsilon (See below).
Please NOTE that if I use NON-parabolic inlet (i.e. fixedValue), everything is fine - I got a good converged solution.
I used Upwind Div scheme with cellLimited interpolation scheme.
I have tried both PCG and GAMG for pressure, and PBiCG and GAMG for U|k|epsilon.
I have also tried varying URF.
I suspect the problem is in my BCs and bad starting solution for k and epsilon (since the flow is now parabolic from the inlet).
But, I can't figure out. I've also tried setting parabolic inlet profiles for k and epsilon to no avail.
Please Help anyone!.
the 0/epsilon:
Quote:
inlet
{
type turbulentMixingLengthDissipationRateInlet;
mixingLength 0.05;
value uniform 1e-06;
}
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the 0/k:
Quote:
inlet
{
type turbulentIntensityKineticEnergyInlet;
intensity 0.05;
value uniform 0.0001;
}
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Thank you very much.
I hope I do get any help this time.
Please.. It's quite difficult to get help from this forum.
Regards,
Stefano
Code:
Time = 2
DILUPBiCG: Solving for Ux, Initial residual = 0.00855909, Final residual = 7.45812e-10, No Iterations 17
DILUPBiCG: Solving for Uy, Initial residual = 0.0467024, Final residual = 6.71306e-10, No Iterations 17
DILUPBiCG: Solving for Uz, Initial residual = 0.0490525, Final residual = 5.95911e-10, No Iterations 18
GAMG: Solving for p, Initial residual = 0.192423, Final residual = 8.18271e-11, No Iterations 40
GAMG: Solving for p, Initial residual = 0.0344647, Final residual = 6.74495e-11, No Iterations 35
GAMG: Solving for p, Initial residual = 0.0101951, Final residual = 7.61577e-11, No Iterations 32
time step continuity errors : sum local = 8.98665e-13, global = 1.02105e-14, cumulative = 6.25679e-15
[4] #0 Foam::error::printStack(Foam::Ostream&) in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/lib/linux64GccDPOpt/libOpenFOAM.so"
[4] #1 Foam::sigFpe::sigFpeHandler(int) in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/lib/linux64GccDPOpt/libOpenFOAM.so"
[4] #2 __restore_rt at sigaction.c:0
[4] #3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/lib/linux64GccDPOpt/libOpenFOAM.so"
[4] #4 void Foam::divide<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/lib/linux64GccDPOpt/libincompressibleRASModels.so"
[4] #5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::operator/<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/lib/linux64GccDPOpt/libincompressibleRASModels.so"
[4] #6 Foam::incompressible::RASModels::RNGkEpsilon::correct() in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/lib/linux64GccDPOpt/libincompressibleRASModels.so"
[4] #7 main in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/applications/bin/linux64GccDPOpt/simpleFoam"
[4] #8 __libc_start_main in "/lib64/libc.so.6"
[4] #9 Foam::regIOobject::writeObject(Foam::IOstream::streamFormat, Foam::IOstream::versionNumber, Foam::IOstream::compressionType) const in "/home/stefano/OpenFOAM/OpenFOAM-1.7.0/applications/bin/linux64GccDPOpt/simpleFoam"
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