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Porous Media in PimpleFoam - DF coefficients independency |
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Luiz Oliveira
Join Date: Aug 2018
Location: Napoli, Italy
Posts: 24
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Hello,
I am conducting a simulation of a lateral cavity placed along a riverbank. As vegetation naturally occurs in those regions, I am trying to investigate its effect. The vegetation is being represented by a momentum drag imposed by a porous media, which is a well accepted simplification. what I realized from my past simulations are that the Ergun coefficients were overestimating the resistance in the porous media (PM). Thus, a hunt begun in order to find the appropriate values. I managed to simulate until the order of 1E-25 for both D and F. Although, it seems that the resistance didn't change along the way, as there were no differences in the velocity curve. It appears that there is no communication between the zones despite the mesh being sharing the same points. I noticed that while the flow stabilizes there is a flux that goes into the porous media although after the stabilization no more energy seems to go into the zone giving U = 0 m/s throughout the domain. I came with some hypothesis:
Code:
embayment { type explicitPorositySource; active true; selectionMode cellZone; cellZone embayment; explicitPorositySourceCoeffs { selectionMode cellZone; cellZone embayment; type DarcyForchheimer; mu mu; d (116.62 116.62 4.51E-04); //Original values d (116.62 116.62 4.51E-04); f (3.09 3.09 6.08E-03); //Original values f (3.09 3.09 6.08E-03); coordinateSystem { origin (0.25 0.30 0); e1 (1 0 0); e2 (0 1 0); } } } Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: v1912 | | \\ / A nd | Website: www.openfoam.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location system; object fvSchemes; } ddtSchemes { default backward; } gradSchemes { default leastSquares; } divSchemes { default none; div(phi,U) Gauss LUST grad(U); div(phi,nuTilda) Gauss linear; div((nuEff*dev2(T(grad(U))))) Gauss linear; div(phi,tracer) Gauss limitedLinear 0 1; } interpolationSchemes { default linear; } laplacianSchemes { default Gauss linear uncorrected; } snGradSchemes { default uncorrected; } wallDist { method meshWave; } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: v1912 | | \\ / A nd | Website: www.openfoam.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location system; object fvSolution; } PIMPLE { nOuterCorrectors 1; nCorrectors 3; nNonOrthogonalCorrectors 0; pRefCell 0; pRefValue 0; residualControl { "(p|U)" { tolerance 1e-06; relTol 0; } } relaxationFactors { fields { p 0.3; pFinal 1; } equations { U 0.7; UFinal 1; nuTilda 1; nuTildaFinal 1; } } } solvers { p { solver GAMG; smoother GaussSeidel; tolerance 1e-06; relTol 0; maxIter 100; } pFinal { $p; smoother GaussSeidel; tolerance 1e-06; relTol 0; } U { solver PBiCGStab; preconditioner diagonal; tolerance 1e-06; relTol 0; maxIter 100; } UFinal { $U; tolerance 1e-06; relTol 0; } tracer { solver PBiCGStab; preconditioner diagonal; tolerance 1e-06; relTol 0; minIter 1; } } relaxationFactors { fields { p 0.3; pFinal 1; } equations { U 0.7; UFinal 1; nuTilda 1; nuTildaFinal 1; } } // ************************************************************************* // |
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Tags |
les, pimplefoam, porous media, transient |
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