# Problems solving T Equation in separated flow using a second Order Closure Model

 Register Blogs Members List Search Today's Posts Mark Forums Read

 October 25, 2012, 14:09 Problems solving T Equation in separated flow using a second Order Closure Model #1 New Member   Join Date: Oct 2012 Posts: 16 Rep Power: 6 Hi everybody, I am trying to simulate the flow over a heated backward facing step by means of a modified simpleFoam solver which uses a second order Closure Model for the turbulent heat fluxes. The model worked pretty well in the heated turbulent channel. But it doesn't work for the Backward facing step in combination with a RSM turbulence model such as the LaunderGibson. I did a pre-calculation based on the RSM model and Fouriers Law for the scalar fluxes. I already tried different solver settings and schemes in the fvSolvers and fvSolutions file. Currently the files look as follows: Code: /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.1 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { p { solver PCG; preconditioner DIC; tolerance 1e-08; relTol 0.01; } U { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0.1; } k { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0.1; } epsilon { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0.1; } R { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0.1; } nuTilda { solver PBiCG; preconditioner DILU; tolerance 1e-08; relTol 0.1; } T BICCG 1e-08 0.01; } SIMPLE { nNonOrthogonalCorrectors 0; } relaxationFactors { p 0.3; U 0.5; k 0.5; epsilon 0.5; R 0.5; nuTilda 0.5; T 0.3; } // ************************************************************************* // fvSchemes: Code: /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.1 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; } divSchemes { default none; div(phi,U) Gauss upwind; div(phi,k) Gauss upwind; div(phi,epsilon) Gauss upwind; div(phi,R) Gauss upwind; div(R) Gauss linear; div(phi,nuTilda) Gauss upwind; div((nuEff*dev(T(grad(U))))) Gauss linear; div(phi,T) Gauss upwind; div((Dp&grad(p))) Gauss linear; div((S&grad(p))) Gauss linear; } laplacianSchemes { default none; laplacian(nuEff,U) Gauss linear corrected; laplacian((1|A(U)),p) Gauss linear corrected; laplacian(DkEff,k) Gauss linear corrected; laplacian(DepsilonEff,epsilon) Gauss linear corrected; laplacian(DREff,R) Gauss linear corrected; laplacian(DnuTildaEff,nuTilda) Gauss linear corrected; laplacian(((nu|0.7123)+(nut|0.86)),T) Gauss linear corrected; laplacian(kappaEff,T) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(U) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p ; } // ************************************************************************* // The error message is as follows: Code: #0 Foam::error::printStack(Foam::Ostream&) in "/home/pascal/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/home/pascal/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 in "/lib/x86_64-linux-gnu/libc.so.6" #3 Foam::PBiCG::solve(Foam::Field&, Foam::Field const&, unsigned char) const in "/home/pascal/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #4 Foam::fvMatrix::solve(Foam::dictionary const&) in "/home/pascal/OpenFOAM/OpenFOAM-2.1.1/platforms/linux64GccDPOpt/lib/libfiniteVolume.so" #5 at simpleFoam_YSC_q.C:0 #6 in "/home/pascal/OpenFOAM/pascal-2.1.1/platforms/linux64GccDPOpt/bin/simpleFoam_YSC_q" #7 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #8 in "/home/pascal/OpenFOAM/pascal-2.1.1/platforms/linux64GccDPOpt/bin/simpleFoam_YSC_q" Floating point exception (core dumped) Any help appreciated! Regards, Pascal

 November 19, 2012, 11:29 #2 Senior Member     Daniel P. Combest Join Date: Mar 2009 Location: St. Louis, USA Posts: 585 Rep Power: 20 Can you post your code and let us know what model you are using? This error message is pretty general and could be a number of things. I did this one in the past using another scalar flux model other than the gradient diffusion hypothesis. __________________ Dan Find me on twitter @dancombest and LinkedIn

 Tags convergence, error, openfoam, separation

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post nileshjrane OpenFOAM Running, Solving & CFD 4 February 25, 2013 05:13 tH3f0rC3 OpenFOAM 7 February 23, 2013 06:37 heavy_user OpenFOAM 16 February 11, 2012 06:15 Artex85 OpenFOAM Running, Solving & CFD 9 January 3, 2012 09:06 velan OpenFOAM Running, Solving & CFD 1 October 17, 2008 05:36

All times are GMT -4. The time now is 19:55.