# problems k-epsilon for 3-D Fully turbulent Square-Pipe flow

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 February 16, 2017, 10:18 problems k-epsilon for 3-D Fully turbulent Square-Pipe flow #1 New Member   Jorgen van Koppen Join Date: Feb 2017 Location: Stuttgart, Germany Posts: 1 Rep Power: 0 Dear Openfoamers, I have some problems with the solutions i get from my kepsilon model (also tried the other versions, RNG and realizable). The problem is that while according to the high Reynolds number ( v = 44 m/s, nu = 1.5e-4) the flow in the pipe should develop to a Turbulent flow it goes to a laminar profile (see pictures). The Y+ is around 30-50 so that shouldnt be a problem I have already tried changing solver settings and boundary condition values but that would not give a better solution. Same for making the mesh finer. I hope any of you might be able to help me with finding the problem since i'm stuck and haven't been able to find anything online so far. Picture shows flow close to the end of the square pipe. The settings i have are the flowing and are based on tutorials and research: The pipe dimensions for the square pipe are: y = 0.1016 meter z = 0.1524 meter x = 5.12 meter Making it a square pipe with Inlet, 4 walls and an Outlet So the blockMesh looks like this: Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.1 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object blockMeshDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // convertToMeters 0.01; vertices ( // General form (just the inlet) (-512.70 1.27 0) // 0 ( 0 1.27 0) // 1 ( 0 11.43 0) // 2 (-512.70 11.43 0) // 3 (-512.70 1.27 15.24) // 4 ( 0 1.27 15.24) // 5 ( 0 11.43 15.24) // 6 (-512.70 11.43 15.24) // 7 ); blocks ( // normal blocks without yplus extra //block 1 hex (0 1 2 3 4 5 6 7) (200 35 50) simpleGrading (0.1 ((0.5 0.5 5) (0.5 0.5 0.2)) ((0.5 0.5 5) (0.5 0.5 0.2)) ) ); edges ( ); boundary ( inlet { type patch; faces ( (0 3 7 4) ); } outlet { type patch; faces ( (1 2 6 5) ); } upperWall { type wall; faces ( (3 2 6 7) ); } lowerWall { type wall; faces ( (0 1 5 4) ); } sideWallleft { type wall; faces ( (0 1 2 3) ); } sideWallright { type wall; faces ( (4 5 6 7) ); } ); mergePatchPairs ( ); // ************************************************************************* //``` Epsilon: inlet: fixed value 168, outlet: zeroGradient walls: epsilonWallFunction: uniform 168 K inlet: turbulentIntensityKineticEnergyInlet: intensity 0.032 value 3.05 outlet: zeroGradient walls: kqRWallFunction: uniform 3.05 U inlet: timeVaryingMappedFixedValue with a Turbulent profile as input, average 44 (m/s) outlet: zeroGradient walls: noSlip p inlet: zeroGradient outlet: fixedvalue uniform 0 walls: zeroGradient nut inlet: calculated uniform 0 outlet: calculated uniform 0 walls: nutkWallFunction uniform 0 and for the solver and solution settings: Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.1 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object controlDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // application simpleFoam; startFrom startTime; startTime 0; stopAt endTime; endTime 2000; deltaT 1; writeControl timeStep; writeInterval 50; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression off; timeFormat general; timePrecision 6; runTimeModifiable true; functions { #includeFunc streamlines } // ************************************************************************* //``` Code: ```/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 4.1 | | \\ / 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-12; relTol 0.001; smoother GaussSeidel; minIter 3; maxIter 100; nPreSweeps 1; nPostSweeps 3; nFinestSweeps 3; scaleCorrection true; directSolverCoarsestLevel false; cacheAgglomeration on; nCellsInCoarsestLevel 500; agglomerator faceAreaPair; mergeLevels 1; } U { solver PBiCG; preconditioner DILU; tolerance 1e-09; relTol 0.1; } k { solver PBiCG; preconditioner DILU; tolerance 1e-09; relTol 0.1; } epsilon { solver PBiCG; preconditioner DILU; tolerance 1e-09; relTol 0.1; } R { solver PBiCG; preconditioner DILU; tolerance 1e-09; relTol 0.1; } nuTilda { solver PBiCG; preconditioner DILU; tolerance 1e-09; relTol 0.1; } omega { solver PBiCG; preconditioner DILU; tolerance 1e-09; relTol 0.1; } } // "(U|k|epsilon|omega|f|v2)" // { // solver smoothSolver; // smoother symGaussSeidel; // tolerance 1e-06; // relTol 0; // nSweep 1; // maxIter 100; // } SIMPLE { nNonOrthogonalCorrectors 0; } // consistent yes; // residualControl // { // p 1e-5; // U 1e-5; // "(k|epsilon|omega|f|v2)" 1e-12; // } //} relaxationFactors { p 0.3; U 0.7; k 0.7; epsilon 0.7; R 0.7; nuTilda 0.7; } //relaxationFactors //{ // equations // { // U 0.95; // 0.9 is more stable but 0.95 more convergent // ".*" 0.95; // 0.9 is more stable but 0.95 more convergent // } //} // ************************************************************************* //``` Thank you very much in advance! And if you need more info let me know. Greetings, Jorgen