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Recommended way of generating mesh from cad

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Old   May 9, 2008, 13:54
Default Hi Bernhard, fine, shouldn'
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Mattijs Janssens
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Hi Bernhard,

fine, shouldn't break anything (I hope)
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Old   May 10, 2008, 04:39
Default I have tried the updated autoR
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Terry Barnaby
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I have tried the updated autoRefineMesh, and it looks much better now. I have got a test case working, thanks. I am having a few problems with a more complex geometry where the solver crashes (car-2.stl, there is a warning? in checkMesh of "multiply connected surface (shared edge)"). I will play a bit more with this.
For info my current test case that works is at:
ftp://portal.beam.ltd.uk/pub/vwtTest2.tar.gz

Note that this could be completely wrong (but it does give nice pictures (in the test case archive) !) ...
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Old   May 13, 2008, 03:55
Default Hi Terry, I succeeded in me
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Mark Couwenberg
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Hi Terry,

I succeeded in meshing your case and later on also my case. Want went wrong: I had to add directory before the stl-file in cellSetDict/autoRefineMeshDict. So instead of:
file "car.stl"
I had to fill in:
file ".vwtTest2/car.stl"
Very simple, if you know... The error with respect to octreedatatrisurface etc (see above) was caused by this omission.
However, now I meshed my case but I am not satisfied. The blockMesh is simply modified by removing the bricks around the surface. Simply refining the mesh around the surface until you get sufficient accuracy is not very efficient (at least not for my cases). It should be possible to cut the cells following the contours of the surface, without even refining. Next challenge. Anyone any ideas?

Regarding your questions: I have no ideas about your checkMesh warnings. However I have some experience with other (free) mesher tools. I am working on a complete installation of caelinux. This comes with a complete linux installation, openfoam, paraview and some modellers/meshers. Salome is a program which is able to import cad geometries, or to make your own geometry from scratch. It also incorporates a mesher module using netgen/tetgen. Quiet ok, though on some of my (perfectly checked and cleaned) geometries it did not succeed.
Even simpler is using gmsh. Free, fast and simple. Simplicity comes at the price of restricted possiblities but for simple cases it is more than ok and I am quiet sure that your windtunnel/car model is perfectly meshed by this tool, with tets though.

Brgds,

Mark
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Old   May 13, 2008, 06:52
Default I have managed to get my mesh
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Terry Barnaby
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I have managed to get my mesh better, simply by making autoRefineMesh refine the blocks more.
My current test case is at:
ftp://portal.beam.ltd.uk/pub/vwtTest4.tar.gz

I will have a look at gmsh. Originally it looked to me that gmsh would not be able to generate meshes around objects such as I would need for a VWT.

Are tet meshes Ok to use for this purpose ?
I read somewhere that hex meshes were better for the solvers ?


Cheers

Terry
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Old   March 19, 2009, 21:31
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Ahmed
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Quote:
Originally Posted by christian67 View Post
Hi everybody,
maybe somebody might be interested:

There is a 3D CAD software called GraphiteOne 3D CAD which is free for non-commercial use.

With this CAD you can export stl and step files (e.g. for netgen).
It's also possible to export 3D dxf files (e.g. to make wireframes for dxf3geo ==> gmsh).

They seem to use the OpenCascade libraries, but there are pre-compiled binaries for some distributions, that can be installed by normal human beeings.

www.graphiteone-cad.com

Good luck,

Christian
This is what you would read on their web portal

GraphiteOne can be downloaded on this web page for evaluation purposes to test GraphiteOne for 30 days. After the evaluation period terminates. you can licence GraphiteOne for unlimited usage. For more information about licencing GraphiteOne, please refer to licencing GraphiteOne.


why do you post incorrect information
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