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[ICEM] Mesh patches

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Old   August 16, 2014, 06:47
Default Mesh patches
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Govindaraju
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hai
please check the attached geometry when i import mesh geometry created in ICEM CFD to CFX for analysis, I found some patches. How do I rectify it. wHEN i RUN THE SIMULATION i FACE THIS PROBLEM
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Old   August 21, 2014, 09:00
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Dear All

Please find the mesh file . I could not create quality mesh . The cfx solver comes with error. There are bad elements present. I am very new to this software. if you people guide me I can finish my work earlier


https://www.dropbox.com/s/gipygarswd...arify.zip?dl=0


Thank you
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Old   August 22, 2014, 03:08
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Dear all

Any guidance to complete the mesh

Thank you
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Old   August 22, 2014, 07:37
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Sebastian Engel
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Hello kmgraju,

inside the pipe ends you created an ogrid to get better element qualities. That's good practice.
But the ogrid doesn't follow into the Y-Block-Section. You should create the Y-Block before generating the ogrid in the whole volume.

The way you have done it (probalby alle pipe ends seperately) is not a good way as you noticed. You need to find a way to generate the ogrid in "one run". Play around with the selections! I would start by selecting all blocks and the faces of the inlet and outlet boundaries.
It might be possible to start with seperate ogrid, but it's more complex, one has to select the right faces

After you created your ogrids, you moved or even merged vertices to positions where neighboring blocks were degenerated to triangular blocks or blocks without any volume. Numerically they are still there! And these blocks are the main source of your problems.

Try to avoid by all means fitting a hexa block into a triangular shape (cases with wedge elements needed are rare). Numerically the contained elements stay hexas, even if the graphic output looks different. Simply spoken, no solver will give you a meaningfull result with degenerated elements or negative volume elements.

Another tip, use the quality checks! A simple rule, the determinant of the premesh must be all positive. Check for Elements with negative determinant and determinant close to 0.
Check out the help and tutorials for the features "Index Control", "Scan planes". They help a lot to find flaws in a blocking.

I hope you get some new ideas to improve your mesh =)

With regards,
Sebastian
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Old   August 22, 2014, 08:29
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Quote:
Originally Posted by bluebase View Post
Hello kmgraju,

inside the pipe ends you created an ogrid to get better element qualities. That's good practice.
But the ogrid doesn't follow into the Y-Block-Section. You should create the Y-Block before generating the ogrid in the whole volume.

The way you have done it (probalby alle pipe ends seperately) is not a good way as you noticed. You need to find a way to generate the ogrid in "one run". Play around with the selections! I would start by selecting all blocks and the faces of the inlet and outlet boundaries.
It might be possible to start with seperate ogrid, but it's more complex, one has to select the right faces

After you created your ogrids, you moved or even merged vertices to positions where neighboring blocks were degenerated to triangular blocks or blocks without any volume. Numerically they are still there! And these blocks are the main source of your problems.

Try to avoid by all means fitting a hexa block into a triangular shape (cases with wedge elements needed are rare). Numerically the contained elements stay hexas, even if the graphic output looks different. Simply spoken, no solver will give you a meaningfull result with degenerated elements or negative volume elements.

Another tip, use the quality checks! A simple rule, the determinant of the premesh must be all positive. Check for Elements with negative determinant and determinant close to 0.
Check out the help and tutorials for the features "Index Control", "Scan planes". They help a lot to find flaws in a blocking.

I hope you get some new ideas to improve your mesh =)

With regards,
Sebastian
Dear Sebastian

Thank you for your guidance . I will try but I am very new to this software. I am learning myself without any other people help. Only help I can get from this forum
Thank you
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