# turbDyMFoam settings

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March 18, 2010, 10:52
turbDyMFoam settings
#1
New Member

Michael Buchmayr
Join Date: Mar 2010
Posts: 16
Rep Power: 8
Hi everybody!

we are trying to calculate the transient turbulent flow through a pump, yet with little success. We where using turbDymFoam, with a uniform (p and U) initial calculation domain. The calculation somehow diverges, and we can't figure out why.
The fvSchemes we set look as follows:
Quote:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default Euler; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; } divSchemes { default none; div(phi,U) Gauss linearUpwind Gauss; div(phi,k) Gauss upwind; div(phi,epsilon) Gauss upwind; div(phi,omega) Gauss upwind; div(phi,R) Gauss upwind; div(R) Gauss linear; div(phi,nuTilda) Gauss upwind; div((nuEff*dev(grad(U).T()))) 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(DomegaEff,omega) Gauss linear corrected; laplacian(DREff,R) Gauss linear corrected; laplacian(DnuTildaEff,nuTilda) Gauss linear corrected; laplacian(rAU,p) Gauss linear corrected; laplacian(rAU,pcorr) Gauss linear corrected; laplacian(nu,U) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(U) linear; interpolate(HbyA) linear; interpolate(1|A) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; pcorr; } // ************************************************** *********************** //
We now wanted to initialize the field with a steady state solution using MRFSimpleFoam. But again -> ocillating residuals.

Does anybody have an idea what we could have done wrong?

March 18, 2010, 10:54
#2
New Member

Michael Buchmayr
Join Date: Mar 2010
Posts: 16
Rep Power: 8
Forgot the solution schemes

Quote:
 solvers { p PCG { preconditioner DIC; tolerance 1e-05; relTol 0.0002; minIter 2; maxIter 5; }; pFinal PCG { preconditioner DIC; tolerance 1e-05; relTol 0.0001; minIter 2; maxIter 5; }; U BiCGStab { preconditioner { type DILU; } minIter 1; maxIter 10; tolerance 1e-07; relTol 0; }; k BiCGStab { // and epsilon preconditioner { type DILU; } minIter 1; maxIter 5; tolerance 1e-07; relTol 0; }; epsilon BiCGStab { preconditioner { type DILU; } minIter 1; maxIter 5; tolerance 1e-07; relTol 0; }; omega BiCGStab { preconditioner { type DILU; } minIter 1; maxIter 5; tolerance 1e-07; relTol 0; }; R GAMG { preconditioner GAMG; tolerance 1e-06; relTol 0.1; agglomerator faceAreaPair; nCellsInCoarsestLevel 10; mergeLevels 1; smoother GaussSeidel; minIter 0; maxIter 100; cacheAgglomeration true; nPreSweeps 0; nPostSweeps 2; nFinestSweeps 2; }; nuTilda GAMG { preconditioner GAMG; tolerance 1e-06; relTol 0.1; agglomerator faceAreaPair; nCellsInCoarsestLevel 10; mergeLevels 1; smoother GaussSeidel; minIter 0; maxIter 100; cacheAgglomeration true; nPreSweeps 0; nPostSweeps 2; nFinestSweeps 2; }; } SIMPLE { nNonOrthogonalCorrectors 2; } PISO { momentumPredictor no; nCorrectors 3; nNonOrthogonalCorrectors 2; nGammaCorr 1; nGammaSubCycles 4; cGamma 1; } relaxationFactors { p 0.3; U 0.7; k 0.7; epsilon 0.7; omega 0.7; R 0.7; nuTilda 0.7; } // ************************************************** *********************** //

 August 4, 2010, 08:14 #3 Member   Nick Gardiner Join Date: Apr 2009 Location: Chichester, UK Posts: 93 Rep Power: 9 Hi Try running turbFoam on it first to get reasonable values for k and epsilon. I have momentumPredictor yes; in my PISO loop. Don't know if that's going to make a difference but the initial turbulence model variables certainly affect the stability. Good luck

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