Discretization settings Foam vs. Fluent
Dear Foamers,
Iīm interested in the the performance of Fluent 6.3.26 in comparison with OpenFoam 1.5. Iīm simulating a steady (simpleFoam solver in OF 1.5), isothermal, single phase problem using the realizable k-epsilon-model. In order to get accurate results for my flow field, I chose the "second-order upwind" descritization scheme (for pressure, momentum, k, epsilon) in Fluent. Here my Question: How do I have to change the fvScheme-skript in OpenFoam to get the same settings as in Fluent? I made different approaches using the "linearUpwind"-scheme. But it didīnt work, due to some errors. Iīm not sure if "linearUpwind" is comparable to the "second-order upwind" scheme in Fluent. I would appreciate any hints or help. Thanks in advance. wuppdupp Among others I used this fvScheme script: FoamFile { version 2.0; format ascii; class dictionary; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linearUpwind; grad(p) Gauss linearUpwind; grad(U) Gauss linearUpwind; } divSchemes { default none; div(phi,U) Gauss linearUpwind; div(phi,k) Gauss linearUpwind; div(phi,epsilon) Gauss linearUpwind; div(phi,R) Gauss linearUpwind; div(R) Gauss linearUpwind; div(phi,nuTilda) Gauss linearUpwind; div((nuEff*dev(grad(U).T()))) Gauss linearUpwind; } 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; } interpolationSchemes { default linearUpwind; interpolate(U) linearUpwind; } snGradSchemes { default corrected; } fluxRequired { default no; p; } // ************************************************** *********************** // |
Dear Wuppdupp,
Maybe the scheme that you need is QUICK. Search the forum for related posts. I personally use GammaV for velocity. Best Regards, Paulo Rocha |
Dear paulo,
I tried Quick and GammaV. (For the gradSchemes) Without success. The only Schemes which work are linear an fourth. |
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Try it. Best Regards, Paulo Rocha |
Hi Paulo,
thankīs for your advice. It works fine. Is there any possibility to use higher order discretization schemes also for the gradSchemes and the interpolationSchemes? I was quite confused because in the OF documentation is mentioned, that you can use other Schemes also for gradSchemes and interpolationSchemes. Again, thank you very much! Wuppdupp |
Yes,
if you write something wrong in the schemes text, OpenFOAM will show you all the possibilities. The books of Ferziger & Peric / Versteeg & Malalasekra have good explanation about many schemes. Best Regards, Paulo Rocha |
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For interpolation schemes the choice is wider (see tab 4.6 in the manual). The "cubic" is fourth order central scheme, and it exists in the limited version "limitedCubic". Best, |
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