how to handle non-closed surfaces in STL
 

Hi Foamers

I will use a STL file with snappyHexMesh, though.
But I came to know that there were non-closed surfaces on STL file after using surfaceCheck.
I know there are some of utilities concerning STL like surfaceHookUp, etc.
Which one is the best way to fix the non-closed surfaces? otherwise, I will need to use a third party CAD software?
I hope I will be able to handle this matter without using third party programs like ANSA, Hypermesh, etc
Please let me know it if you have experiences like that.

Thank you.

Hello,

The holes/cracks shall not be a problem if they are smaller than the cell size you apply locally.
You can close holes in meshLab, which is a nice open-source tool for processing and editing of surface meshes.

Regards,

Franjo

Hi Dustin. I know it is a very old thread. But I really need help. I need to mesh a wedge shaped geometry. I have seven different patches for that. I am willing to use snappy hex mesh. I prepared 7 different stl files. But when I used cat command, the single stl file is not closed. What should I do now. Please help me.
[Moderator note: moved from http://www.cfd-online.com/Forums/ope...hexmesh-2.html]

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When I join my stl files of different boundary patches the joined surface is not closed but it should be. What should I do now. Please help me.
[Moderator note: moved from http://www.cfd-online.com/Forums/ope...surface-2.html]

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Hi Franjo
I have the same problem. I have prepared 7 different stl files for 7 boundary patches. But when I check to see if they together make a watertight body it says not all surface closed. In Meshlab I could not see any holes. Can you please help me how I can solve this problem?

Quick question @zannatul: What does this command give you?
Note: Replace "your_stl_file_name.stl" with your STL file name ;)

Hi Bruno
Thanks for your response. Earlier surface check command was showing that surface is not closed. Now I have solved the problem and its showing surface is closed, all surfaces are connected to two faces. :)

Hi zannatul!
I hv a problem juz like you..how did you do that...plz advice me....

Hi Thazin

At first I was exporting my CAD geometry in stl format and then I was dividing it into different patches. I had a very fine opening in my geometry and by exporting it in stl format I was not being able to find that hole. Then I exported it in step file format. After that when I selected my patches I could identify where is the problem in my geometry. So I Redraw my geometry and could export different patches directly from solidworks. Then I used cat commend and checked again. It was closed. I hope this could help you. Good luck!

Zannatul

Thanks!!
But I'm not like you cuz I'm using meshlab. And I can't redraw my geometry because it's changed DEM( digital elevation model) into stl format.

Hi Franjo,

you are right that if the cell size is bigger than the gap it should not be a problem BUT after the last few years I realized that you can get crazy meshing results if you have non-closed stl's. My collegue also used non closed STL's (complex casting stuff) and got crazy results and unexpected behavior all the time. After I fixed the STL with my tools (Blender + SALOME), meshing was so nice and the results.

I only can recommend to have a good triangulated (not CAD exported) STL. Anyway this is my personal opinion (:

For reparing you can use SALOME or BLENDER.

PS: If someone send me a case to check and I see that the surfaceCheck gives a not closed surface, I will not investigate further (:

Hi together

I think I have a similar problem with my STL's. I created my geometry with Autodesk Inventor and then imported it to Salome to subdevide some regions and export them as STL like in this video https://www.youtube.com/watch?v=ObsFQUiVi1U&t=180s .

Now the problem is that after I've used the cat tool in Linux on my subdivided regions and used surfaceCheck on it it says that the surface is not closed. But when I check the whole STL from Salome it says the surface is closed. So I guess the problem is somewhere in the cutting process with salome.

I've tried to fix it with meshlab but there I don't even see any holes. Is it possible that there went something wrong in the cat process? I would be very thankful if someone would be so kind and take a look at my STL.

Attachment 67661


Edit: found this post of you and will try it this way first

https://www.cfd-online.com/Forums/op...sh-salome.html

Edit 2: Well it works but only if I just use groups of faces. Not when I use operation tools like cut, fuse and so on. Isn't that possible?