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[snappyHexMesh] snappyHexMesh addLayers questions |
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May 21, 2021, 16:24 |
snappyHexMesh addLayers questions
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#1 |
New Member
Lukas Kutej
Join Date: Jan 2016
Location: Darmstadt
Posts: 20
Rep Power: 10 |
Hello, I am trying to mesh a channel by snappyHexMesh for LES without wall function.
To capture small eddies near to the wall, which is crucial to prevent the velocity overshoot in velocity profile (caused by superstreaks) I am refining the mesh in near wall region in all three directions. That's the idea... But when I go with delta_x+, delta_y+ and delta_z+ to 1, then I go crazy with total # of cells... 1.) So I am happy with corser cells but I WANT TO SPLIT the first cell layer in normal direction... How can I do this? To remain whole mesh and just split the first layer? My idea was, to define boundary layer of two layers of total hight same als the first cell layer. But I have this feeling that snappy shift some cell layers over the boundary layer when I create them. You can see that behaviour on my pictures. (oh...on the picture there is the boundary layer made by two layers with expansionRation 2 - this was my best solution to keep the cell hight in first two layers) 2.) How can I prevent to colapse the boundary layer in the corner please? I set featureAngle 180 but I am not happy :-) |
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May 21, 2021, 17:48 |
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#2 |
New Member
Lukas Kutej
Join Date: Jan 2016
Location: Darmstadt
Posts: 20
Rep Power: 10 |
...could I have a additional question: is it possible to generate a boundary layer higher than one cell layer please? Let's say two times higher with 6 layers?
So higher than this one on the picture... |
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May 24, 2021, 17:52 |
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#3 |
New Member
Lukas Kutej
Join Date: Jan 2016
Location: Darmstadt
Posts: 20
Rep Power: 10 |
I made some progress...
the key is to switch from medial-axis algorithm (default) to meshShrinker: // maxThicknessToMedialRatio 0.3; //medial-axis // minMedialAxisAngle 90; //medial-axis meshShrinker displacementMotionSolver; solver displacementLaplacian; displacementLaplacianCoeffs { diffusivity quadratic inverseDistance (wall1 wall2 etc); } additional: - in fvSolution: solvers { cellDisplacement { solver GAMG; smoother GaussSeidel; tolerance 1e-7; relTol 0.01; } } - in fvSchemes: gradSchemes { default Gauss linear; } laplacianSchemes { laplacian(diffusivity,cellDisplacement) Gauss linear corrected; } But could someone help me please how can I prevent collapsing of the boundary layer in the corner? I would really appreciate that... :-) |
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May 24, 2021, 17:54 |
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#4 |
New Member
Lukas Kutej
Join Date: Jan 2016
Location: Darmstadt
Posts: 20
Rep Power: 10 |
see picture...
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