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wikstrom June 12, 2009 09:29

Extrudemesh
 
1 Attachment(s)
Hi,

I think there is a serious bug in extrudeMesh. Using the linearNormal model, all cells created become inside out. Extruding with negative thickness produces a valid mesh. (that ofcourse can be moved into the desired place with transformPoints, but this workaraound feels a bit awkward.)

Attacheed is a test case describing this. Run the included run.sh with argument negative and positive.

Cheers
Niklas

mattijs June 16, 2009 07:21

Hi Niklas,

the normal is indeed reversed. Agree it is probably not logical. I'd rather not change the behaviour in 1.5.x but will in future versions.

Thanks,

Mattijs

sbence December 6, 2009 07:59

extrudeMesh - hexa cells generated?
 
Dear Foamers,

I am trying to create a 2D mesh to be used in OpenFOAM with snappy. My method is the following:
  1. create a mesh in snappy, thickness should be large enough to have a few nice layers in the middle
  2. create a cellSet containing these nice layers in the middle
  3. create new mesh based on the cellSet with subsetMesh; the new mesh has almost planar patches on the sides
  4. autoPatch and select a face for extrusion
  5. extrudMesh using the right patch
My problem is that the generated mesh contains hexa cells and pyramids as well. So it is not a real extrusion, because the extrusion would result in hexas and wedges only.

Some explanatory screenshots:
Result with snappy:
http://picasaweb.google.com/lh/photo...eat=directlinkhttp://lh5.ggpht.com/_ATh6nWRxZGQ/Sx...800/step-1.png
cellSet from the middle:
http://lh4.ggpht.com/_ATh6nWRxZGQ/Sx...wWo/step-2.png
new mesh from cellSet:
http://lh6.ggpht.com/_ATh6nWRxZGQ/Sx...B4U/step-3.png
patch to extrude (why the triangles are not visualized in paraview?):
http://lh3.ggpht.com/_ATh6nWRxZGQ/Sx...GK8/step-4.png
result mesh with extrudeMesh:
http://lh4.ggpht.com/_ATh6nWRxZGQ/Sx...800/step-5.png
the same visualized in engrid. different colors > different cell types:
http://lh3.ggpht.com/_ATh6nWRxZGQ/Sx...0/engrid-0.png
pyramids visualized in engrid:
http://lh6.ggpht.com/_ATh6nWRxZGQ/Sx...0/engrid-3.png
tetras visualized in engrid:
http://lh4.ggpht.com/_ATh6nWRxZGQ/Sx...0/engrid-4.png

How can I avoid pyramids/tetras?

Thanks for any help!

Bence
http://www.cfd-online.com/home/bence/Desktop/step-1.png


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