Nonlinear k epsilon Shih Model
Hallo Foamers!
Does anybody know a reference where I can find the derivation of the Nonlinear k e Shih model? Cheers 
Does really nobody knows a reference, at least one? HELP

Does really nobody knows a reference, at least one? HELP

Hi Claus,
the paper you are searching for can be found at the NASA pages. There you have access to a lot of other papers of Shih: http://ntrs.nasa.gov/search.jsp?R=35...%257c1%26N%3D0 Best regards, Olli 
Hi,
have you simulated successful using this turbulencemodel? I have problems near walls (U isn't zero orthogonal to the wall in the nearwallpart even in channelflows). Regards Thomas 
Hi,
yes I'm using this turbulence model for simulating swirling flows. For this purpose it seems to be perfect. I haven't discovered any problems until know. Olli 
Hi,
I have velocities out of the wall. I have described this in a posting here in the forum. http://www.cfdonline.com/Forums/ope...inearshih.html But if I'm using a very fine mesh (y+ < 0.4) the results are better. So the solution has a meshdependence. Maybe it's caused by the fvschemss are the solvers for p,U,k... I have tried different ones without success. Could you maybe show your fvschemes and the fvSolutiondata, please? Thanks and regards, Thomas 
Hi Thomas,
a y+ of less than 0.4 seems to be a sufficient fine mesh. Nevertheless, are kepsilon models known for their bad boundary layer behaviour. Therefore this model uses an boundary layer model in the near wall region. I can look up how it is set up. If the results have a meshdependence you should probably do a grid study :( An other way would be to use an much coarser mesh, if boundary layers are not priorranking. Olli fvSchemes:  ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; // grad(U) cellLimited Gauss linear 1; } divSchemes { default none; div(phi,U) Gauss linearUpwindV Gauss linear; div(phi,k) Gauss upwind; div(phi,omega) Gauss upwind; div((nuEff*dev(grad(U).T()))) Gauss linear; div(nonlinearStress) Gauss linear; div(phi,epsilon) Gauss upwind; div(phi,R) Gauss upwind; div(R) Gauss linear; div(phi,nuTilda) Gauss upwind; } laplacianSchemes { default Gauss linear corrected; // default Gauss linear limited 0.5; // default Gauss linear limited 0.333; laplacian(nuEff,U) Gauss linear corrected; laplacian((1A(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; } interpolationSchemes { default linear; interpolate(U) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; } fvSolution:  solvers { p { solver GAMG; preconditioner FDIC; mergeLevels 1; smoother GaussSeidel; agglomerator faceAreaPair; nCellsInCoarsestLevel 100; tolerance 1e06; relTol 0.01; } U { solver GAMG; preconditioner DILU; tolerance 1e05; relTol 0.1; mergeLevels 1; smoother GaussSeidel; agglomerator faceAreaPair; nCellsInCoarsestLevel 100; tolerance 1e05; relTol 0; } k { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0.1; } epsilon { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0.1; } R { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0.1; } nuTilda { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0.1; } } SIMPLE { nNonOrthogonalCorrectors 0; } relaxationFactors { p 0.2; U 0.5; k 0.7; epsilon 0.7; R 0.7; nuTilda 0.7; } 
Hi,
thank you very much. I have simulated using your given condition, but the velocities didn't get better. Have you ever simulated a nonswirling flow using this model? Regards Thomas 
Hi,
no, I never simulated a nonswirling case with this model. I just used the model because all other models either crashed or over predicted the axial velocity. I looked at your other post and really have no idea what is going wrong there. Olli 
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