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self intersecting geometry error

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Old   October 16, 2012, 14:29
Default self intersecting geometry error
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adam
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I get this error after I assign parts to regions and I try to create a volume mesh. I have a solid object in a duct that is an assembly, and then the duct itself. I fill holes at the ends, and then extract the volume to get the air region. Then I send everything to regions. The interfaces are created as you would expect, but then when I mesh STAR says that the solid object is a self-intersecting geometry. I double checked the actual solid model and it does not have intersecting faces, so how could this be? I thought it was because I'm sending duplicate parts to regions but all I'm doing is extracting the volume, nothing more.

Here is a link to the sim file if anyone has the courage and patience to play around with it and tell me what I'm doing wrong:

http://www.sendspace.com/file/wr00au
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Old   October 17, 2012, 01:38
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siamak rahimi ardkapan
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I think you need to work on your parts one more step before assigning them to a region.
You need to use Boolian functions. Please search in Help to find the solution.
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Old   November 3, 2012, 18:53
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Srikar Sai
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Hey,

Assuming the problem still persists, one suggestion I could give is to look specifically for "Pierced faces" in your geometry before volume meshing it. There should be none of them actually.

If you do not find any pierced faces with your initial surface, you can just try to remesh the initial surface ( if using surface remesher) and then run a mesh diagnostics on the remeshed surface (Representation- Remeshed surface - (right click) Repair surface).

In my experience I have found that some details of the starting surface are not captured if I give a size which is to coarse for the remesher. Thereby resulting in intersecting faces on some areas of the surface.

Also its an advice to always use the remesher before volume meshing any surface in CCM+.
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Old   November 21, 2012, 00:10
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Anoop Kumar
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Hey hi ,

I am new to this forum, sry dont know how to message in this site,

let focus on problem , plz dont use volume meshing & surface meshing combined. First surface mesh (keep automatic surface repair off) then go for volume mesh .

in surface mesh give custom surface size to the boundary which are intersecting with ducts wall. Also cut the feature edge properly, then after surface mesh check mesh quality, if there are some priced face fix them manually , then go for volume mesh
i hope this will work.

regards
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Old   November 22, 2012, 18:57
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ank909, you can easily perform both steps at the same time. The precondition is that you've defined your surface right. If you haven't done this, it doesn't help to split it in two steps and "fix pierced faces manually".

Unfortunately I didn't find the time yet to have a look on the model, but I'm pretty sure that it can either be solved by a simple merge/imprint or the model built is just wrong and should be done right.
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