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[ICEM] Dealing with detached curves

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Old   August 12, 2013, 09:23
Default Dealing with detached curves
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Matthew Rich
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Hi all


I am having difficulty getting lines attached to surfaces. I went through and was patching up surfaces not paying attention to the curves whatsoever. My initial mesh had some holes and I was reading that was attributed to not having clean curves. So now I am going back through part by part trying to fix them up. If I use the diagnostic tool, I get the figure below. Very little red or blue and I am not sure how to fix? I tried extracting curves from surfaces but that gives me all greens and making surfaces from green lines doesn't help either.

Any advice? Pulling my hair out here thanks in advance.
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Old   August 12, 2013, 13:10
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So I went through the material on the FAQs... still stuck

I am flying blind so I went to the simplest component in my model, which are two rectangular prisms. I posted another screen shot. Curve extraction produces green. I used the diagnostic tool and it flipped most of the lines red. I am trying to have these last 2 green lines change to red but no luck. When I run the diagnostic they get deleted. Any ideas? Do I have to have all my curves red to mesh in ICEM? Am I better off meshing in WB or something?
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Old   August 12, 2013, 19:46
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Ghazlani M. Ali
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did you play with the tolerance ?
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Old   August 13, 2013, 08:47
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I did not really helping. Do I have to get rid of all the yellow lines to get a good mesh?
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Old   August 13, 2013, 08:52
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yea, the first thing I would do is check the Geometry => Repair Geometry => Build Diagnostic topology tolerance. Make it smaller than your mesh size or the small side of your prism, but larger than the gaps...

Basically, green just means that your curve is further than that tolerance from any surface edge... Increase the tolerance and your problems may go away...

Build topology is a tricky thing and can easily ruin your model though, so be careful. If your tolerance is too large, it will remove surfaces it sees as duplicate because they are too close together, etc...

If I get a bad model that seems to have a lot of problems with the curves being off the edges of the surfaces, I often just delete all the curves and run build topology from scratch.

If you are using patch independent methods (octree tetra), turn on the options to filter curves and points. If you are planning to use a patch conforming method, make sure those options are unchecked.
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Old   August 13, 2013, 08:54
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Oh yea, if you are using OCTREE tetra, you do not need to clean up all the topology before meshing. Patch independent tetra will still walk over many problems... But a clean model is easier and will avoid meshing issues like sliver elements or leakage.

Similarly, if you are using ICEM CFD Hexa, you pick which curves your blocking is associated with, so again, cleanup is not strictly required, but it can make things easier.
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