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Understanding feature edge refinement and snapping

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Old   May 31, 2012, 07:11
Lightbulb Understanding feature edge refinement and snapping
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Florian
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Hello,

I'm in the process of meshing a 1:4 vehicle aerodynamics wind tunnel with snappyHexMesh. Input files are a bunch of STLs, OF is 2.1.0, solver will be simpleFoam.

The complete snapyHexMeshDict is available at http://pastebin.com/a71XxWHF Any comments welcome!

Using SHM I still have some trouble understanding the feature edge refinement and snapping.

In my snappyHexMeshDict I have resolveFeatureAngle 140. I understand that this creates an edge mesh (same like surfaceFeatureExtract -includedAngle 140).

  1. refinementSurfaces
  2. {
  3. GEOM_windTunnel.stl
  4. { level (5 6); }
  5. }
This edge mesh is used for refinement (to level 6) when cells are intersected by the edge. Is this correct?

Now there is the parameter nFeatureSnapIter 10 which tries to align faces to the features. Does it use the features that are caught by resolveFeatureAngle or does it need to have an edge mesh file given in the features () dict?

I tried it with and without nFeatureSnapIter 10. Both meshes were visually almost identical but the mesh with nFeatureSnapIter enabled was much worse when it came to checkMesh quality measures. Number of cells was around 27M.

Thanks for help & any comments!

Florian
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Old   May 31, 2012, 13:08
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You need to run surfaceFeatureExtract first the use the emesh files generated to mesh the edges.

Have a look at this discussion here:
http://www.cfd-online.com/Forums/ope...ture-edge.html
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