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[ICEM] Hexa-Meshing of sharp edge

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Old   August 6, 2014, 18:02
Default Hexa-Meshing of sharp edge
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Robert Bischof
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Hello together,

for my thesis i have to work with icem cfd and cfx.
Therefore i'm a beginner in using both programms.

I've finished the blocking in icem (after a while) and refined the mesh at various points.
But cfx stops the simulation after 4 iteration (Error: "... c_fpx_handler: floating point exception: overflow" --> i thing it is a numerical problem, caused by the mesh quality)

I investigated the problem and found a region, which have poor elements.

I found the possibility to construct y-blocks, but still there are elements with small angles (13 - 20). Therefor I have found no solution.
Is there another possibility to mesh this region or to refine the mesh? I have to use hexa-elements and i'm not allowed to change the geometry.

There are screenshots of the region and the mesh in the attachment.

For your help, i would be very greatful. Thanks a lot!
Attached Images
File Type: png y-blocks.PNG (7.9 KB, 32 views)
File Type: png y-blocks2.PNG (10.8 KB, 28 views)
File Type: jpg mesh_right_side.jpg (37.3 KB, 30 views)
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Old   August 8, 2014, 08:00
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Sebastian Engel
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Hi Robert, is there are reason you need to mesh this small region with additional blocks? Is it possible to associate the face of the block on top to the cylinder surface? This block would be abit distorted, but generates better cells.

associate.jpg

Last edited by bluebase; August 9, 2014 at 10:58.
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Old   August 8, 2014, 16:48
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Robert Bischof
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Thanks for your answer.
Unfortunately, I can't access my ICEM Modell this evening.
The blocking must be chosen based on the geometry. At Monday I will show some Screenshots for better understanding.

Has anyone else some suggestions ?
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Old   August 19, 2014, 05:38
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Robert Bischof
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For better understanding, I have added some screenshots of my inlet.
On the second picture the visibility of the front surface (of the box) is turned of, so you can the inside the pipe.
There is a rectangular box, which is leading on the pipe. Because of that, there is that region, which belongs to my first post.

Like I said, I'm not allowed to change the geometry. Has anybody an idea for my problem ?

Greetings
Attached Images
File Type: png inlet_pipe1.png (8.3 KB, 9 views)
File Type: png inlet_pipe2.png (11.2 KB, 8 views)
File Type: png inlet_pipe_mesh.png (61.4 KB, 13 views)
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Old   August 19, 2014, 15:25
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Sijal Ahmed Memon (turboenginner@gmail.com)
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Quote:
Originally Posted by biro View Post

I found the possibility to construct y-blocks, but still there are elements with small angles (13 - 20).
you can use tri mesh in that region and merge it with the rest of the mesh.

But 13 deg is not a bad angle at all... you can try it in CFX...
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Old   August 19, 2014, 16:56
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Today I have tried to start a job without the pipe and the bad regions (I deleted the section and started it in CFX) and the job is running. When I will start the job with the pipe and the bad regions, CFX stops with the error i wrote in the first post. So I think, that I have to change the blocking there!?

I don't know how to merge the mesh with tri elements, can someone explain?
I'm sorry for that question, but thats new for me! Thank you!
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Old   August 19, 2014, 17:09
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Sijal Ahmed Memon (turboenginner@gmail.com)
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There is tutorial on mesh merge in icem cfd help...
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Old   August 19, 2014, 17:17
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Ok, thank you. I will look for it tomorrow
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