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Problem with boundary layer - noSlip condition not being respected - OpenFOAM |
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July 11, 2019, 16:38 |
Problem with boundary layer - noSlip condition not being respected - OpenFOAM
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New Member
Vitor Heitor Cardoso
Join Date: Jan 2019
Location: Rio de Janeiro
Posts: 10
Rep Power: 7 |
Dear community,
I've been running a few validation tests comparing numerical methods (FVM, FEM, FDM) for flow through parallel plates. I have the the following setups, which are also attached: - Flow: Laminar, developed, incompressible; - Flow through parallel plates -> Length = 1 mm, Height = 0,250 mm, thickness = 20 micrometers) - Fluid: Water (rho = 1000kg/m³, mu = 0,001 Pa.s -> nu = 1e-6 m²/s) - Pressure-Driven Flow: Inlet Pressure: 1 Pa ( 0,001 Pa/rho) When I run the simulation, I have very promissing results in a global analysis. However, when I analyze the behavior of the flow next to the walls, I realize the "noSlip" condition is not being respected. Does anyone knows what could be resulting this behavior? I was studying about y+ and stuff but I have low understanding about it so far, but I thought y+ stuff were influential only on turbulent flow (I might be terribly wrong). (I'm sorry for the attachments on the text, but I couldnt upload the files) Thanks in advance. Best Regards, Vitor #-------------------------- Attached Files---------------------------------------------# p Dictionary object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { Inlet { type fixedValue; value uniform 0.001; } Outlet { type fixedValue; value uniform 0; } TopWall { type zeroGradient; } BottomWall { type zeroGradient; } FrontAndBack { type zeroGradient; } } -------------------------------------------------------------------------------------------------------- U dictionary object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { Inlet { type pressureInletVelocity; value uniform (0 0 0); } Outlet { type zeroGradient; } TopWall { type noSlip; } BottomWall { type noSlip; } FrontAndBack { type noSlip; } } --------------------------------------------------------------------------------------------------------------- fvSchemes object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; grad(p) Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss linearUpwind grad(U); div(phi,k) bounded Gauss limitedLinear 1; div(phi,epsilon) bounded Gauss limitedLinear 1; div(phi,omega) bounded Gauss limitedLinear 1; div(phi,v2) bounded Gauss limitedLinear 1; div((nuEff*dev2(T(grad(U))))) Gauss linear; div(nonlinearStress) Gauss linear; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; } wallDist { method meshWave; } ---------------------------------------------------------------------------- fvSolution solvers { p { solver PCG; preconditioner DIC; tolerance 1e-07; relTol 0.1; //smoother GaussSeidel; } "(U|k|epsilon|omega|f|v2)" { solver smoothSolver; smoother symGaussSeidel; tolerance 1e-07; relTol 0.1; } } SIMPLE { nNonOrthogonalCorrectors 0; consistent yes; residualControl { p 1e-5; Ux 1e-5; Uy 1e-5; "(k|epsilon|omega|f|v2)" 1e-3; } } relaxationFactors { equations { U 0.9; // 0.9 is more stable but 0.95 more convergent ".*" 0.9; // 0.9 is more stable but 0.95 more convergent } } ------------------------------------------------------------------------------------------------------------------------------------- checkMesh Results: Checking geometry... Overall domain bounding box (0 0 0) (0.001 0.00025 2e-05) Mesh has 3 geometric (non-empty/wedge) directions (1 1 1) Mesh has 3 solution (non-empty) directions (1 1 1) Boundary openness (1.59928e-17 2.1878e-17 -1.73529e-18) OK. Max cell openness = 2.2343e-16 OK. Max aspect ratio = 2.95283 OK. Minimum face area = 1.07169e-12. Maximum face area = 6.31543e-12. Face area magnitudes OK. Min volume = 1.78608e-18. Max volume = 7.55579e-18. Total volume = 5e-12. Cell volumes OK. Mesh non-orthogonality Max: 39.3315 average: 9.2241 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.465947 OK. Coupled point location match (average 0) OK. Mesh OK. End |
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boundary layer flow, noslip |
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