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oepnfoam naca0012 I can not get the correct lift coefficient and drag coefficient |
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#1 |
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cheng
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Hello everyone, I am using SA model and simplefoam to solve the lift coefficient and drag coefficient of NACA0012. I adjusted many aspects, but I can't get the correct result. The lift coefficient obtained is 1.011, but the reference value is about 1.2. The drag coefficient is 0.037, and the reference value is around 0.012.
My nut is 1e-5 and nuTilda is 4e-5. If them are too small, case will crash. Re=6e+6, nu=1e-6, rho=1000, U=6, I can't get the correct result. Does anyone know where my settings are going wrong? FoamFile { version 2.0; format ascii; class dictionary; location "system"; object controlDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // application simpleFoam; startFrom startTime; startTime 0; stopAt endTime; endTime 0.24; deltaT 0.0001; writeControl timeStep; writeInterval 100; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression off; timeFormat general; timePrecision 6; runTimeModifiable true; functions { forceCoeffs { type forceCoeffs; functionObjectLibs ("libforces.so"); patches (FOIL); log true; rho rhoInf; rhoInf 1000; CofR (0 0 0); liftDir (-0.17365 0.984808 0); dragDir (0.984808 0.17365 0); pitchAxis (0 0 1); magUInf 6; lRef 1; Aref 0.3048; //This is the thickness of the grid in the Z direction. writeControl adjustableRunTime; writeInterval 0.1; } |
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#2 |
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cheng
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FoamFile
{ version 2.0; format ascii; class volScalarField; object nuTilda; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -1 0 0 0 0]; internalField uniform 4e-5; boundaryField { INLET { type freestream; freestreamValue uniform 4e-5; } OUTLET { type freestream; freestreamValue uniform 4e-5; } FOIL { type fixedValue; value uniform 0; } frontAndBackPlanes { type empty; } } FoamFile { version 2.0; format ascii; class volScalarField; object nut; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -1 0 0 0 0]; internalField uniform 1e-5; boundaryField { INLET { type freestream; freestreamValue uniform 1e-5; } OUTLET { type freestream; freestreamValue uniform 1e-5; } FOIL { type nutUSpaldingWallFunction; value uniform 0; } frontAndBackPlanes { type empty; } FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (5.9088465 1.041889 0); boundaryField { INLET { type freestreamVelocity; freestreamValue $internalField; } OUTLET { type freestreamVelocity; freestreamValue $internalField; } FOIL { type noSlip; } frontAndBackPlanes { type empty; } } FoamFile { version 2.0; format ascii; class volScalarField; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { INLET { type freestreamPressure; freestreamValue $internalField; } OUTLET { type freestreamPressure; freestreamValue $internalField; } FOIL { type zeroGradient; } frontAndBackPlanes { type empty; } } FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss linearUpwind grad(U); div(phi,nuTilda) bounded Gauss linearUpwind grad(nuTilda); div((nuEff*dev2(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } wallDist { method meshWave; } FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { p { solver GAMG; tolerance 1e-06; relTol 0.1; smoother GaussSeidel; } U { solver smoothSolver; smoother GaussSeidel; nSweeps 2; tolerance 1e-08; relTol 0.1; } nuTilda { solver smoothSolver; smoother GaussSeidel; nSweeps 2; tolerance 1e-08; relTol 0.1; } } SIMPLE { nNonOrthogonalCorrectors 0; residualControl { p 1e-5; U 1e-5; nuTilda 1e-5; } } relaxationFactors { fields { p 0.3; } equations { U 0.7; nuTilda 0.7; } } |
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#3 |
Senior Member
Herpes Free Engineer
Join Date: Sep 2019
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Hi,
Would the following link help? https://www.cfd-online.com/Forums/op...tml#post800233 This issue seems to need a revisit. Please let us know your feedback. Thanks a lot.
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#4 | |
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cheng
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#5 | |
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cheng
Join Date: Apr 2021
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If you want I can sent to you my project Looking forward to your reply! Create time Create mesh for time = 0 Time = 0 Mesh stats points: 298000 internal points: 0 faces: 594212 internal faces: 296212 cells: 148404 faces per cell: 6 boundary patches: 3 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 148404 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology airfoil 596 1192 ok (non-closed singly connected) freestream 596 1192 ok (non-closed singly connected) leftAndRight 296808 298000 ok (non-closed singly connected) Checking faceZone topology for multiply connected surfaces... No faceZones found. Checking basic cellZone addressing... No cellZones found. Checking geometry... Overall domain bounding box (-249.487 -249.992 -0.5) (250.425 249.992 0.5) Mesh has 2 geometric (non-empty/wedge) directions (1 1 0) Mesh has 2 solution (non-empty) directions (1 1 0) All edges aligned with or perpendicular to non-empty directions. Boundary openness (4.68794e-19 -7.21221e-20 3.01413e-19) OK. Max cell openness = 1.74033e-15 OK. Max aspect ratio = 72.8739 OK. Minimum face area = 1.86956e-09. Maximum face area = 73.9388. Face area magnitudes OK. Min volume = 1.86956e-09. Max volume = 73.9388. Total volume = 196252. Cell volumes OK. Mesh non-orthogonality Max: 21.9774 average: 5.92132 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.23925 OK. Coupled point location match (average 0) OK. Mesh OK. End |
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Tags |
drag coeffient, lift coefficient, naca0012, openfoam |
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