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Worse accuracy in LES models than in RANS models |
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August 30, 2017, 05:56 |
Worse accuracy in LES models than in RANS models
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Diego Ferrando
Join Date: Mar 2017
Location: Zaragoza
Posts: 19
Rep Power: 9 |
Hi Foamers.
I have computed the first case from: http://www.aij.or.jp/jpn/publish/cfdguide/index_e.htm I have used LES and RANS models to compare the accuracy and computation time from different models but the accuracy on LES models is worse than RANS models. According to Blocken's paper: http://www.sciencedirect.com/science...45793013000959 The Hit rate(q) in LES models is around 0.9. My results in OF are the followings: Spalart Allmaras RANS model q = 0.72 Smagorinsky LES model q = 0.59 I don't understand which is going wrong with LES model. OF case files: 0/U: Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { in { type fixedProfile; profile csvFile; profileCoeffs { nHeaderLine 0; // number of header lines refColumn 0; // reference column index componentColumns (1 2 3); // component column indices separator ","; // optional (defaults to ",") mergeSeparators no; // merge multiple separators fileName "0/Uprofile.csv"; // name of csv data file outOfBounds clamp; // optional out-of-bounds handling interpolationScheme linear; // optional interpolation scheme } direction (0 0 1); origin 0; } out { type pressureInletOutletVelocity; value uniform (0 0 0); } laterales { type noSlip; } techo { type noSlip; } suelo { type noSlip; } bloque { type noSlip; } } // ************************************************************************* // Code:
0,0,0,0 0.006,2.745,0,0 0.012,2.935,0,0 0.024,3.175,0,0 0.048,3.435,0,0 0.072,3.627,0,0 0.096,3.824,0,0 0.12,4.021,0,0 0.144,4.21,0,0 0.168,4.362,0,0 0.192,4.491,0,0 0.198,4.502,0,0 0.204,4.586,0,0 0.216,4.606,0,0 0.228,4.712,0,0 0.252,4.854,0,0 0.276,4.993,0,0 0.3,5.132,0,0 0.36,5.449,0,0 0.42,5.782,0,0 0.48,6.077,0,0 0.54,6.338,0,0 0.6,6.588,0,0 0.66,6.693,0,0 0.72,6.751,0,0 0.88,6.751,0,0 Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { in { type zeroGradient; } out { type totalPressure; p0 uniform 0; gamma 1.4; value uniform 0; } laterales { type zeroGradient; } techo { type zeroGradient; } suelo { type zeroGradient; } bloque { type zeroGradient; } } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object nut; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -1 0 0 0 0]; internalField uniform 0; boundaryField { in { type calculated; value uniform 0; } out { type calculated; value uniform 0; } laterales { type nutkWallFunction; value uniform 0; } techo { type nutkWallFunction; value uniform 0; } suelo { type nutkWallFunction; value uniform 0; } bloque { type nutkWallFunction; value uniform 0; } } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object transportProperties; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // transportModel Newtonian; nu [0 2 -1 0 0 0 0] 1.5e-05; // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "constant"; object turbulenceProperties; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // simulationType LES; LES { LESModel Smagorinsky; turbulence on; printCoeffs on; delta cubeRootVol; cubeRootVolCoeffs { deltaCoeff 1; } PrandtlCoeffs { delta cubeRootVol; cubeRootVolCoeffs { deltaCoeff 1; } smoothCoeffs { delta cubeRootVol; cubeRootVolCoeffs { deltaCoeff 1; } maxDeltaRatio 1.1; } Cdelta 0.158; } vanDriestCoeffs { delta cubeRootVol; cubeRootVolCoeffs { deltaCoeff 1; } smoothCoeffs { delta cubeRootVol; cubeRootVolCoeffs { deltaCoeff 1; } maxDeltaRatio 1.1; } Aplus 26; Cdelta 0.158; } smoothCoeffs { delta cubeRootVol; cubeRootVolCoeffs { deltaCoeff 1; } maxDeltaRatio 1.1; } } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object controlDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // application pisoFoam; startFrom latestTime; startTime 0; stopAt endTime; endTime 7; deltaT 0.0001; writeControl timeStep; writeInterval 5000; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression off; timeFormat general; timePrecision 6; runTimeModifiable true; //adjustTimeStep yes; //maxCo 1; functions { fieldAverage1 { type fieldAverage; libs ( "libfieldFunctionObjects.so" ); writeControl writeTime; timeStart 2; timeEnd 7; fields ( U { mean yes; prime2Mean yes; base time; } ); } probes { type probes; libs ("libsampling.so"); writeControl writeTime; timeStart 2; timeEnd 7; fields ( UMean UPrime2Mean U ); probeLocations ( (-0.06 0 0.01) (-0.06 0 0.04) (-0.06 0 0.08) (-0.06 0 0.12) (-0.06 0 0.14) (-0.06 0 0.16) (-0.06 0 0.17) (-0.06 0 0.19) (-0.06 0 0.22) (-0.06 0 0.28) (-0.04 0 0.17) (-0.04 0 0.19) (-0.04 0 0.22) (-0.04 0 0.28) (-0.02 0 0.17) (-0.02 0 0.19) (-0.02 0 0.22) (-0.02 0 0.28) (0 0 0.17) (0 0 0.19) (0 0 0.22) (0 0 0.28) (0.04 0 0.17) (0.04 0 0.19) (0.04 0 0.22) (0.04 0 0.28) (0.06 0 0.01) (0.06 0 0.04) (0.06 0 0.08) (0.06 0 0.12) (0.06 0 0.14) (0.06 0 0.16) (0.06 0 0.17) (0.06 0 0.19) (0.06 0 0.22) (0.06 0 0.28) (0.1 0 0.01) (0.1 0 0.04) (0.1 0 0.08) (0.1 0 0.12) (0.1 0 0.14) (0.1 0 0.16) (0.1 0 0.17) (0.1 0 0.19) (0.1 0 0.22) (0.1 0 0.28) (0.16 0 0.01) (0.16 0 0.04) (0.16 0 0.08) (0.16 0 0.12) (0.16 0 0.14) (0.16 0 0.16) (0.16 0 0.17) (0.16 0 0.19) (0.16 0 0.22) (0.16 0 0.28) (0.26 0 0.01) (0.26 0 0.04) (0.26 0 0.08) (0.26 0 0.12) (0.26 0 0.14) (0.26 0 0.16) (0.26 0 0.17) (0.26 0 0.19) (0.26 0 0.22) (0.26 0 0.28) (-0.06 0 0.01) (-0.06 -0.02 0.01) (-0.06 -0.04 0.01) (-0.06 -0.05 0.01) (-0.06 -0.07 0.01) (-0.06 -0.09 0.01) (-0.06 -0.12 0.01) (-0.06 -0.16 0.01) (-0.04 -0.05 0.01) (-0.04 -0.07 0.01) (-0.04 -0.09 0.01) (-0.04 -0.12 0.01) (-0.04 -0.16 0.01) (-0.02 -0.05 0.01) (-0.02 -0.07 0.01) (-0.02 -0.09 0.01) (-0.02 -0.12 0.01) (-0.02 -0.16 0.01) (0 -0.05 0.01) (0 -0.07 0.01) (0 -0.09 0.01) (0 -0.12 0.01) (0 -0.16 0.01) (0.04 -0.05 0.01) (0.04 -0.07 0.01) (0.04 -0.09 0.01) (0.04 -0.12 0.01) (0.04 -0.16 0.01) (0.06 0 0.01) (0.06 -0.02 0.01) (0.06 -0.04 0.01) (0.06 -0.05 0.01) (0.06 -0.07 0.01) (0.06 -0.09 0.01) (0.06 -0.12 0.01) (0.06 -0.16 0.01) (0.1 0 0.01) (0.1 -0.02 0.01) (0.1 -0.04 0.01) (0.1 -0.05 0.01) (0.1 -0.07 0.01) (0.1 -0.09 0.01) (0.1 -0.12 0.01) (0.1 -0.16 0.01) (0.16 0 0.01) (0.16 -0.02 0.01) (0.16 -0.04 0.01) (0.16 -0.05 0.01) (0.16 -0.07 0.01) (0.16 -0.09 0.01) (0.16 -0.12 0.01) (0.16 -0.16 0.01) (0.26 0 0.01) (0.26 -0.02 0.01) (0.26 -0.04 0.01) (0.26 -0.05 0.01) (0.26 -0.07 0.01) (0.26 -0.09 0.01) (0.26 -0.12 0.01) (0.26 -0.16 0.01) (-0.06 0 0.1) (-0.06 -0.02 0.1) (-0.06 -0.04 0.1) (-0.06 -0.05 0.1) (-0.06 -0.07 0.1) (-0.06 -0.09 0.1) (-0.06 -0.12 0.1) (-0.06 -0.16 0.1) (-0.04 -0.05 0.1) (-0.04 -0.07 0.1) (-0.04 -0.09 0.1) (-0.04 -0.12 0.1) (-0.04 -0.16 0.1) (-0.02 -0.05 0.1) (-0.02 -0.07 0.1) (-0.02 -0.09 0.1) (-0.02 -0.12 0.1) (-0.02 -0.16 0.1) (0 -0.05 0.1) (0 -0.07 0.1) (0 -0.09 0.1) (0 -0.12 0.1) (0 -0.16 0.1) (0.04 -0.05 0.1) (0.04 -0.07 0.1) (0.04 -0.09 0.1) (0.04 -0.12 0.1) (0.04 -0.16 0.1) (0.06 0 0.1) (0.06 -0.02 0.1) (0.06 -0.04 0.1) (0.06 -0.05 0.1) (0.06 -0.07 0.1) (0.06 -0.09 0.1) (0.06 -0.12 0.1) (0.06 -0.16 0.1) (0.1 0 0.1) (0.1 -0.02 0.1) (0.1 -0.04 0.1) (0.1 -0.05 0.1) (0.1 -0.07 0.1) (0.1 -0.09 0.1) (0.1 -0.12 0.1) (0.1 -0.16 0.1) (0.16 0 0.1) (0.16 -0.02 0.1) (0.16 -0.04 0.1) (0.16 -0.05 0.1) (0.16 -0.07 0.1) (0.16 -0.09 0.1) (0.16 -0.12 0.1) (0.16 -0.16 0.1) (0.26 0 0.1) (0.26 -0.02 0.1) (0.26 -0.04 0.1) (0.26 -0.05 0.1) (0.26 -0.07 0.1) (0.26 -0.09 0.1) (0.26 -0.12 0.1) (0.26 -0.16 0.1) ); } } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default CrankNicolson 0.9; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss linearUpwind grad(U); div(phi,p) Gauss linear; div((nuEff*dev2(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } wallDist { method meshWave; } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { p { solver GAMG; tolerance 1e-07; relTol 0.1; smoother GaussSeidel; } pFinal { $p; smoother DICGaussSeidel; tolerance 1e-6; relTol 0; }; "(U|B)" { solver smoothSolver; smoother GaussSeidel; tolerance 1e-05; relTol 0; } } PISO { nCorrectors 2; nNonOrthogonalCorrectors 0; } relaxationFactors { fields { p 0.3; } equations { U 0.7; ".*" 0.7; } } // ************************************************************************* // |
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Tags |
accuracy, hit rate, jia, les, rans |
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