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[ICEM] Help~how to mesh a fluid domain when I have to subtract volumes in ICEM

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Old   October 8, 2018, 06:26
Smile Help~how to mesh a fluid domain when I have to subtract volumes in ICEM
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Ivy
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Greetings!
I'd like to simulate the airflow in the boundary layer of atmosphere and there are some cubes which stand for buildings in my fluid domain.(like this)

I used to use gambit to mesh my model by using “subtract volumes” and then split it to mesh. However, it seems that ICEM doesn't have such function.
In order to complete the mission and solve the problem, I search on Youtube and found this helpful vedio(https://www.youtube.com/watch?v=VTac...MnOy0Pz-9QCAPS).
The blogger creates a block and splits it to many small blocks and then deletes the small block of the cube.
However, this vedio only has one cube, so I can block and delete it easily, what if I had many cubes in fluid domain? Is it right to split to many blocks and delete the cube-blocks one by one, or there are other ways?
Deeply greatful for your help!

Last edited by stardust; October 8, 2018 at 07:35.
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Old   October 8, 2018, 08:29
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Gert-Jan
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Depends on what type of mesh you want to create. If hexa, then use the method you described. If you want a tetrahedral mesh, then just create a material point in the air, and turn on the mesher (robust,octree). ICEM will find out it there are isolated volumes, and will delete these automatically and only the mesh in the air will remain.

Last edited by Gert-Jan; October 8, 2018 at 12:34.
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Old   October 9, 2018, 05:28
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Hi Ivy,


ICEM's kernel is based on surfaces only. Assume that ICEM isn't able to recognize volumes, unless you have a watertight geometry with a material point inside.
For hexa meshes the material point isn't even needed.



Creating a blocking for the shown geometry (your's) is fairly easy. I suggest you to just repeat the splitting and deleting as shown in the video. You should notice, that you'll "reuse" a split for the blocks in the same direction which saves some work.
If this is insane for you, you could also write a script to automize the generation. However, i wouldn't suggest this for a beginner in ICEM. It's a different language than for Gambit. And probably takes more time than doing it manually. Nevertheless, a good starting point for a script would be to record the manuall blocking! Then you could modify it, if you need to do this more often. Going further down this road would require an introduction to TCL (a interpreted language). Then you'll probably learn how to modify your recorded script to make it useable for large amounts of cubes.
To some extend i can help on the scripting part here (proffesional advisory on request).



Even for a mesh proffesional in gambit, i strongly suggest you to do the tutorials of ICEM. They might be boring, but ICEM is considerable different to Gambit.




Best regards,
Sebastian
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Old   October 9, 2018, 10:36
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Quote:
Originally Posted by Gert-Jan View Post
Depends on what type of mesh you want to create. If hexa, then use the method you described. If you want a tetrahedral mesh, then just create a material point in the air, and turn on the mesher (robust,octree). ICEM will find out it there are isolated volumes, and will delete these automatically and only the mesh in the air will remain.
Got it, thank you ^_^
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Old   October 9, 2018, 10:41
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Quote:
Originally Posted by bluebase View Post
Hi Ivy,


ICEM's kernel is based on surfaces only. Assume that ICEM isn't able to recognize volumes, unless you have a watertight geometry with a material point inside.
For hexa meshes the material point isn't even needed.



Creating a blocking for the shown geometry (your's) is fairly easy. I suggest you to just repeat the splitting and deleting as shown in the video. You should notice, that you'll "reuse" a split for the blocks in the same direction which saves some work.
If this is insane for you, you could also write a script to automize the generation. However, i wouldn't suggest this for a beginner in ICEM. It's a different language than for Gambit. And probably takes more time than doing it manually. Nevertheless, a good starting point for a script would be to record the manuall blocking! Then you could modify it, if you need to do this more often. Going further down this road would require an introduction to TCL (a interpreted language). Then you'll probably learn how to modify your recorded script to make it useable for large amounts of cubes.
To some extend i can help on the scripting part here (proffesional advisory on request).



Even for a mesh proffesional in gambit, i strongly suggest you to do the tutorials of ICEM. They might be boring, but ICEM is considerable different to Gambit.




Best regards,
Sebastian
Yes there are lots of differents between ICEM and Gambit. I'll try that and thanks for your valuable advice!
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