Convergence and steady state using simpleFoam

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February 8, 2013, 05:14
Convergence and steady state using simpleFoam
#1
Senior Member

Marco Longhitano
Join Date: Jan 2013
Location: Aachen
Posts: 103
Rep Power: 4
Hi Foamers,

I am doing a simulation of an hydraulic orifice by using simpleFoam. I got many problems about convergence. After several trials, I got a good solution under the physical point of view.

Nevertheless, I still have some doubts regarding the convergence.
Here there are my fv Schemes and my fvSolution files:

Quote:
 ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) Gauss upwind; div(phi,k) Gauss upwind; div(phi,omega) Gauss upwind; div((nuEff*dev(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; }
Quote:
 solvers { /* p { solver PCG; preconditioner DIC; tolerance 1e-12; relTol 0.1; minIter 1; //maxIter 100; }*/ p { solver GAMG; tolerance 1e-12; relTol 0.1; smoother GaussSeidel; nPreSweeps 0; nPostSweeps 2; cacheAgglomeration on; agglomerator faceAreaPair; nCellsInCoarsestLevel 10; mergeLevels 1; } /*U { solver PBiCG; preconditioner DILU; tolerance 1e-12; relTol 0.1; minIter 1; //maxIter 100; }*/ U { solver smoothSolver; smoother GaussSeidel; tolerance 1e-12; relTol 0.1; nSweeps 1; minIter 1; //maxIter 100; } /*k { solver PBiCG; preconditioner DILU; tolerance 1e-12; relTol 0.1; minIter 1; //maxIter 100; }*/ k { solver smoothSolver; smoother GaussSeidel; tolerance 1e-12; relTol 0.1; nSweeps 1; minIter 1; //maxIter 100; } /*omega { solver PBiCG; preconditioner DILU; tolerance 1e-12; relTol 0.1; minIter 1; //maxIter 100; }*/ omega { solver smoothSolver; smoother GaussSeidel; tolerance 1e-12; relTol 0.1; nSweeps 1; minIter 1; //maxIter 100; } } SIMPLE { nNonOrthogonalCorrectors 0; } potentialFlow { nNonOrthogonalCorrectors 10; } relaxationFactors { fields { p 0.3; } equations { U 0.7; k 0.7; omega 0.7; } cache { grad(U); }

As attachments there are all the data regarding convergence!

Although all the variables seems to converge (except for Ux), some of them still oscillate. Must I worry about it??

Additionally, I forced the convergence by edit the tolerance, unless all the variables would have decreased until reach very (VERY!!) low values!

Anyone can tell me if my solution converge or not (and if does it reach a steady state)?

Moreover, what exactly means the continuity graph (plotted by using pyFoam)?

Best Regards
Marco
Attached Images
 finalResidual.png (6.8 KB, 36 views) initialResidual.png (5.4 KB, 29 views) cont.png (3.3 KB, 27 views) bound.png (3.1 KB, 24 views)

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