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[snappyHexMesh] problems with sHM: it doesn't snap!

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Old   September 17, 2013, 05:35
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Claudio
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Dear Foamers,

I'm here again with the same problem.
Unfortunately, I tried to apply your suggestions, Artur's in particular, but what I'm continuing to obtain is the same: a good castellated mesh, but nothing about the snap fase!

I modified the mesh control parameters; I checked the STL file. The final checkMesh gives me no errors nor warnings! So, I don't understand where the problem can be.

I share again my case:
https://www.dropbox.com/sh/h47fw08v6owiaz7/Rmd0_zHRJK

Now I'm using OF 2.2.1 (but nothing changed in the result)

How can you see in the SHM log file, line 1915, the message "Did not succesfully snap mesh. Giving up." appears.

Any suggestion whould be well accepted
Thank you in advance for your help!

Best regards,
Claudio
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Old   November 8, 2013, 12:41
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did you solve the problem, claudio?

I have kind of the same problem (sHM doesn't snap -.-).

I also have many doubts about my stl. I made it in rhino 4, and sHM manages to mesh it (badly), so I would think there are not "problems of closure".
I believe there could be problems with some of the surfaces I created in rhino.
what do you mean with "check if your stl is ok"?
how can I do that?

thanks to all ^^
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Old   November 11, 2013, 05:03
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phil
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Quote:
Originally Posted by KYPCK444 View Post
did you solve the problem, claudio?

I have kind of the same problem (sHM doesn't snap -.-).

I also have many doubts about my stl. I made it in rhino 4, and sHM manages to mesh it (badly), so I would think there are not "problems of closure".
I believe there could be problems with some of the surfaces I created in rhino.
what do you mean with "check if your stl is ok"?
how can I do that?

thanks to all ^^
Welcome,
you can check your mesh with the command "surfaceCheck partname.stl".
This will give you back some information about your .stl file. Especially about a closed surface, nearly exact points, not multiple connected surfaces.

You can use this information to work improve your .stl. In my case (Export stl from CAD) this meant to increase the stl tolerance ratio. After some exports i had a closed surface.

For editing closed vertex etc. (dont know the names of all these errors) you can use the filter options within meshlab (filters -> clean repair).

Hope this will give you some hints where you have to gather new information^^
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Old   November 11, 2013, 06:28
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thank you very much, gelbebanane U.U
I'm going to work on that
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Old   March 18, 2014, 04:51
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Chen Yu
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Did you solve the problem? I have similar problem posting http://www.cfd-online.com/Forums/ope...tml#post480610.

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Originally Posted by KYPCK444 View Post
thank you very much, gelbebanane U.U
I'm going to work on that
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Old   July 10, 2020, 09:06
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Open your stl file in an editor (if it is ASCI format), and on the first line in there, make sure the name of the stl file and the term in front of "solid" are identical.



Quote:
Originally Posted by Claudio87 View Post
Dear Foamers,

I'm writing because I'm having many troubles with snappyHexMesh: it doesn't snap!
I know this is "common": looking around in the forum, I found many others who have had similar problems, but none of the suggested solutions seems working in my case!

My best results are:
- one in which, starting from a very coarse background mesh, it does the snap stage, but the final mesh is useless for the simulation;
- another that would be good for the simulation (I think) but it doesn't snap, so all the surface is done by steps!

The strange thing in the second case is that in the log file of sHM I don't find the typical sentence "did not succesfully snap mesh. Giving up", and in the checkMesh I have no errors!

I tried many different combinations with the Dicts (blockMeshDict and snappyHexMeshDict):
- increasing or decreasing the intial number,
- increasing or decreasing the number of levels in sHMDict, directly for the refinementSurface or in the feature obteined with the command surfaceFeatureExtract,
- increasing the parameters in the subDict "snapControls".

Often it doesn't snap, saying "did not succesfully snap mesh. Giving up"; sometimes it doesn't say anithing, but it similarly doesn't snap!

I have no ideas now about what I can do, and about what is wrong!

I attach these two cases I obtained, with some images.
I hope someone could help me!


Best regards,
Claudio
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