Wierd mesh anomaly

Mesh generators, CAD programs, and other tools
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Gary R
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Joined: 12 Apr 2012, 07:23
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Location: Long Beach CA, USA

Wierd mesh anomaly

Post by Gary R »

I created a simple pipe for a diffusion test. The pipe is in two sections. It was created with FreeCAD and exported via a .brep file to gmsh.
PipeMesh.png
PipeMesh.png (45.29 KiB) Viewed 54 times
, The result, as shown, has a large notch in the mesh. Multiple attempts have failed to improve things. How can I fix this? The .brep file is attached.

Thanks in advance
Gary R.
Attachments
DiffusionTest-BodyRevolution.brep
(18.41 KiB) Downloaded 4 times
kevinarden
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Re: Wierd mesh anomaly

Post by kevinarden »

I imported the brep into gmsh and had the same notch occur
I opened the brep in ElmerGUI and it meshed OK
I imported the brep into salome and it meshed OK
I imported the brep into FREECAD and then exported it as a step file
I imported the step file into gmsh and gmsh meshed it without the notch.
Gary R
Posts: 132
Joined: 12 Apr 2012, 07:23
Antispam: Yes
Location: Long Beach CA, USA

Re: Wierd mesh anomaly

Post by Gary R »

Thanks Kevin
If anyone can shed light on why the notch happened it would be both appreciated and instructive.
I now have a problem with ElmerGUI (I don't think related) but will post that on the ElmerGUI forum.

Thanks again
Gary R.
kevinarden
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Re: Wierd mesh anomaly

Post by kevinarden »

If I start in gmsh with the original brep file and immediately mesh the notch happens. However, if I set the mesh to something finer. Tools, options, mesh, general size factor. Set it to 0.3 instead of 1.0, it meshes ok. It appears gmsh can't follow the surface definition with a coarse mesh size.
Gary R
Posts: 132
Joined: 12 Apr 2012, 07:23
Antispam: Yes
Location: Long Beach CA, USA

Re: Wierd mesh anomaly (solved)

Post by Gary R »

I found the problem. When I ran validation on the Freecad sketch I found 3 missing coincidences. When I fixed these, the problem went away. The moral to this story is run validation on your sketches before proceeding.
Gary R.
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