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-   -   [ICEM] Cleaning Rippled Surfaces in ICEM (http://www.cfd-online.com/Forums/ansys-meshing/110315-cleaning-rippled-surfaces-icem.html)

scribby182 December 7, 2012 18:08

Cleaning Rippled Surfaces in ICEM
 
All,

Thank you for any help you can give.

I have geometry from a parasolid file. I imported it through Workbench and then exported to an ICEM project. Most of the geometry looks good, but when I zoom in on a few of the surface intersections I see facets in the surface (see attached image). Surfaces are being displayed fully (not simple), so I don't think that is it. I can try to rebuild the surfaces from the surrounding curves and that sometimes helps, but sometimes ICEM is unable to rebuild the surfaces at all.

http://postimage.org/image/skslhsybj/

Any suggestions on how to correct these issues (or opinions on whether or not they're going to make a big difference in the mesh)? I'm an intermediate ICEM user and have a pretty good feel for the program, but I don't think I'm using the geometry repairing tools to their fullest. My experience, however, is that whenever you THINK there is a problem with the geometry, if you don't correct it immediately it ends up causing big headaches later.

Thanks again for all your help. Sorry, but I will not be able to post the geometry, blocking, etc. for this as it is a sensitive part.

Scribby182

energy382 December 10, 2012 13:30

have you set up facet quality to value 10 in desgin modeler before you export the geometry?

what i would do:
1. import parasolid to DM
2. set up facet quality to 10
3. export as .agdb-file
4. import in icem as workbenchreader file

that should normally work

have you tried to import parasolid directly to icem?

scribby182 December 10, 2012 16:58

energy, thanks for your response. Along with this surface problem, I'm having a few others that prevent me from trying what you ask...

For some reason, DM itself wont generate my parasolid files. If I make a mesh module in workbench and then just right click and import geometry on the main workbench page, I can import my parasolid. Opening mesh then shows the correct geometry (where I usually then export for ICEM). If I double click on DM, however, and then try to generate the geometry in DM I get the error "All bodies could not be imported because they contain corrupt data structures". I haven't figured the cause of this yet (its especially strange since the geometry is still available in mesh...). Because I can't get the goemetry in DM, I can't try to facet quality fix.

I have also tried importing parasolid directly to ICEM, but when I use that method the parasolid surfaces extend past the curves that were used to cut them (so imagine you had a rectangular surface and cut it in ProE or something to make your parasolid... if I import straight into ICEM then I see the full rectangle (before cut) PLUS the cut in the surface).

If anyone has other suggestions (or fixes to the extra problems) I'd appreciate it. Thanks,

Scribby182

scribby182 December 11, 2012 17:34

In playing with the model and some settings, I found I could improve (but not completely fix) the visuals I was getting by decreasing the triangulation tolerance. If I drop it by 1-2 orders of magnitude it significantly reduces the ripples, but a few still remain.

I have a few follow-up questions about this hopefully someone can answer. I'm just not quite sure how the triangulation tolerance (and similar settings) affect meshing results.

1) If I was to fully mesh this part (including the remaining ripples), would the mesh itself be rippled like the geometry or would the mesh be ok?
2) If I used something like "project to Bsplines", would that correct the problem for the mesh (it doesn't make the geometry surface look any different)?
3) The downside to reducing the triangulation tolerance is the slower panning/rotating/zooming. Is there any reason I shouldn't leave the triangulation tolerance high (ie ~0.01) while I'm manipulating the geometry, but when I get to really detailed meshing (getting everything looking perfect) I then turn the triangulation tolerance down (~0.0001)?

Thanks again for the help,

Scribby182


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