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Improving a mesh with OF utilities

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Old   September 24, 2009, 05:54
Default Improving a mesh with OF utilities
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Matthew Philpott
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I'm having a problem. I imported a mesh from netgen and then did a checkMesh. I get a few sets of bad faces (zeroAreaFaces, non-orthofaces, etc). To get rid of them can I just use something like:
setSet
faceSet zeroFaces delete

or must I use:

setSet
faceSet zeroFaces invert
subsetMesh

or do I have to turn the face set into a cell set (faceToCell?) and then use one of the steps above, but with cellSet? Does cellSet and FaceSet have to work in conjunction with their dictionaries?

None of these utilities have very useful help files, except perhaps setSet. Am I correct to get the help file of a utility to type the util followed by -help, e.g.
cellSet -help
when i do this all i get is a one line usage guide with the parameter possiblities ie. [-batch] [-help] etc.

So many questions! I'm confused. It seems simple enough, but I'm not getting any results. Could I improve my meshing techniques to reduce these zeroArea/nonortho/etc problems happening in the future?
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Old   October 8, 2009, 14:44
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Have you been able to delete the bad cells ? I'm kind of having the similar problem. I think one could create the cellSet from faceToCell , but i'm not sure how to operate delete operation on the whole mesh written in dir 3/

If you have already worked out the solution. Plz post !
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Old   October 12, 2009, 04:50
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haven't figured it out just yet. I managed to delete some nonOrthoCells, but then they didn't have to be converted like faces do. These nonOrthoCells were actually attaced to the zero area faces, so they got deleted too. My model is still ve non orthagonal though, so I'm trying to improve it.
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Old   October 12, 2009, 19:57
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How did you manage to delete the nonOrthogonal Cells?


Quote:
Originally Posted by bigred View Post
haven't figured it out just yet. I managed to delete some nonOrthoCells, but then they didn't have to be converted like faces do. These nonOrthoCells were actually attaced to the zero area faces, so they got deleted too. My model is still ve non orthagonal though, so I'm trying to improve it.
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Old   October 13, 2009, 03:12
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ok, I'm at work at the moment and all my OF stuff is on my home laptop, but if I remember correctly, it was something like:

setSet
cellSet nonOrthoCells delete (you'll have to check the syntax on that and replace nonOrthoCells with the name of the set found in constant/polymesh/sets)
You should now have made a new set called nonOrthoCells (which is filled with everyhting except the ones you deleted) and a new set called nonOrthoCellsOld (or something like that) There is a way to do the delete and save the non deleted cells to another set like goodCells or something, but I'm not sure of the syntax, try typing help once you're in the setSet command.
Then exit setSet by typing quit.
Then type subsetMesh nonOrthoCells (in your case file)
and it'll make a new mesh with all the cells that weren't deleted.
Then do a checkMesh to find out if it's better. Also, don't forget to back up your mesh somewhere. Oh, and it might write the new set to the first time step folder (like 0.1, for example) to prevent overwriting other files, so you might have to copy and paste that into your polymesh folder.

This may also help http://www.cfd-online.com/Forums/ope...checkmesh.html

The documentation is really vague on these commands, I did a google to no avail and I tried to read through the C file, but I'm not a programmer, so it didn't make a whole lot of sense
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Old   October 13, 2009, 13:28
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thats very helpful , I will try .... thanks
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