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July 9, 2010, 08:40 |
LES-kOmegaSSTSAS
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#1 |
Member
Rasoul
Join Date: Feb 2010
Posts: 32
Rep Power: 16 |
Dear Foamer,
My case is a basic case related to turbulent flow over a cylinder. In fact I am going to compare lift&Drag coeffs with the literature data. I succeeded to use RAS-kOmegaSST already. But my results were not accurate enough. Since the accuracy of LES models are better than RAS, I tried to use LES-kOmegaSSTSAS turbulence model for my case. After running, the execution process crashed with the following errors. I think these errors are because of initial values for the turbulence model or used solvers. Am I right? Any body has an idea for the initial values of the nuSgs? I also changed the timeStep, but this has no effect. Time = 0.008 Courant Number mean: 0.00534794 max: 0.0800331 DILUPBiCG: Solving for Ux, Initial residual = 0.0314821, Final residual = 2.40782e-07, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00938822, Final residual = 1.69819e-07, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 0.0736961, Final residual = 3.42136e-07, No Iterations 1 GAMG: Solving for p, Initial residual = 0.429489, Final residual = 0.0295009, No Iterations 3 time step continuity errors : sum local = 9.5465e-08, global = -7.2069e-10, cumulative = -2.89625e-09 GAMG: Solving for p, Initial residual = 0.112661, Final residual = 1.77703e+31, No Iterations 1000 time step continuity errors : sum local = 4.46134e+25, global = 1.33676e+07, cumulative = 1.33676e+07 DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 9.30655e+08, No Iterations 1001 bounding k, min: -10819.8 max: 8259.16 average: -4.75152 DILUPBiCG: Solving for omega, Initial residual = 1, Final residual = 63348.9, No Iterations 1001 bounding omega, min: -5.33351e+37 max: 2.06354e+44 average: 2.12765e+40 ExecutionTime = 21.42 s ClockTime = 24 s Time = 0.01 Courant Number mean: 4.0992e+26 max: 2.81609e+27 DILUPBiCG: Solving for Ux, Initial residual = 0.765954, Final residual = 1.00338, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.910766, Final residual = 118092, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999613, Final residual = 1.01149, No Iterations 1001 #0 Foam::error:rintStack(Foam::Ostream&) in "/home/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::sigFpe::sigFpeHandler(int) in "/home/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Uninterpreted: #3 Foam::GAMGSolver::scalingFactor(Foam::Field<double >&, Foam::Field<double> const&, Foam::Field<double> const&, Foam::Field<double> const&) const in "/home/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #4 Foam::GAMGSolver::scalingFactor(Foam::Field<double >&, Foam::lduMatrix const&, Foam::Field<double>&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const in "/home/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #5 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/home/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #6 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/home/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libfiniteVolume.so" #8 in "/home/OpenFOAM/OpenFOAM-1.6.x/applications/bin/linuxGccDPOpt/pisoFoam" #9 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6" #10 in "/home/OpenFOAM/OpenFOAM-1.6.x/applications/bin/linuxGccDPOpt/pisoFoam" Floating point exception Best regards, Rasoul |
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July 9, 2010, 09:36 |
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#2 |
Senior Member
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Why not use nut from SST result as initial guess for SAS. Actually It is SST based SAS which is not the tranditional LES method
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July 9, 2010, 10:31 |
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#3 |
Member
Rasoul
Join Date: Feb 2010
Posts: 32
Rep Power: 16 |
Dear wayne,
Thank you for your fast reply. But, It's impossible to use nut from RAS-kOmegaSST for LES-kOmegaSSTSAS. Because in the latter model there is no nutwallFunction and we have to use nuSgs instead of nut. Anyway I tried your suggestion and faced with the following error: --> FOAM FATAL ERROR: request for RASModel RASProperties from objectRegistry region0 failed available objects of type RASModel are 0 ( ) Any other suggestion? |
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July 9, 2010, 11:50 |
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#4 |
Senior Member
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you could modify the boundary type in file of k and omega
it is problem of wall function http://www.cfd-online.com/Forums/ope...roperties.html Last edited by waynezw0618; July 21, 2010 at 07:40. |
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