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Horus May 31, 2012 06:11

Understanding feature edge refinement and snapping

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 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!


lovecraft22 May 31, 2012 12:08

You need to run surfaceFeatureExtract first the use the emesh files generated to mesh the edges.

Have a look at this discussion here:

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