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[snappyHexMesh] snappyHexMesh layers at the corner missing

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Old   February 11, 2014, 08:37
Default snappyHexMesh layers at the corner missing
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Yuehan
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Hi Foamers,,

I am using sHM to generate mesh, but usually at the corners the layers are missing. Could anybody tell me how to solve this problem?
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Old   February 11, 2014, 10:41
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When layers are inserted into the mesh, the mesh quality is probably poor and the layers are collapsed. You could
  • make your overall base mesh smaller or bump your refinement level in the corners up a bit
  • Use distance refinement from that surface to refine cells prior to the layer insertion to make small cells so that the mesh quality is not poor enough to cause layer collapse
  • or you could adjust the featureAngle entry in the addlayerControls section to be something like 180. See this presentation for more details, specifically slide44

You may want to start with the last one first....but be careful changing too many things at once to get a desired result. Good Luck!
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Old   February 11, 2014, 15:17
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Quote:
Originally Posted by chegdan View Post
When layers are inserted into the mesh, the mesh quality is probably poor and the layers are collapsed. You could
  • make your overall base mesh smaller or bump your refinement level in the corners up a bit
  • Use distance refinement from that surface to refine cells prior to the layer insertion to make small cells so that the mesh quality is not poor enough to cause layer collapse
  • or you could adjust the featureAngle entry in the addlayerControls section to be something like 180. See this presentation for more details, specifically slide44

You may want to start with the last one first....but be careful changing too many things at once to get a desired result. Good Luck!
Thank you very much.

I have also found that the layers insertion in sHM is very unstable. When I have nSurfaceLayers = 10 then it seems everything is OK, but if I use 15 layers, no layer is inserted. I am totally confused.

Could you provide some hints?
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Old   February 12, 2014, 11:32
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My only hint is that you should slowly add more layers rather than jumping to 150 percent more than where previously successful. You can also try to create a very uniform group of cells where you want to insert layers and this may improve it. Usually, shrinking your base mesh solves many problems with snappyHexMesh. There are many adjustments you can make to the quality measurements but that can make things worse if you aren't careful.
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