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How do you think CFX-Build?

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Old   June 9, 2003, 18:25
Default How do you think CFX-Build?
  #1
David
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CFX-Build almost kill me the desire to be an engineer. I tried to build a drill hole with stell case in it. The hole is 1000m long and the diameter is 9''. In order to save computer resource, I tried to build a cylinder then cut it into quaters. But I got error message when I try to mesh it. Anybody know better mthod to build a model.

Thanks!
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Old   June 9, 2003, 18:32
Default Re: How do you think CFX-Build?
  #2
Glenn Horrocks
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Hi David,

What error message did you get?

Glenn
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Old   June 9, 2003, 18:35
Default Re: How do you think CFX-Build?
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David
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Hi, Glenn,

Thank you for your prompt response. The error message is as follows: Error: ------

Problem: Topology error detected in CAD model.

CAD edge referenced 4 times by faces. Result: Model invalid for meshing. Cause: Invalid model. Action: Please refer to the user documentation

"Using CFX-Build, Section 5 Meshing" for

topological limitations, and modify the

model accordingly.

Solid 3.3.3


Thanks
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Old   June 10, 2003, 03:50
Default Re: How do you think CFX-Build?
  #4
gg
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You have big diference in dimensions (1000m to 9"). Try to use hexa cells in some other mesh package or in CFX-Build if it is possible.

REgards, gg
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Old   June 10, 2003, 18:23
Default Re: How do you think CFX-Build?
  #5
Glenn Horrocks
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Hi David,

As gg said, your hole is very long and thin so the default tetrahedral mesh will not be very good. You should create a hexahedral mesh of the geometry - if you are using CFX 5.6 you can switch that on by changing the meshing mode. It is covered by the documentation.

If you are still on CFX 5.5.1, it is a lot tricker but still possible to make a hexahedral mesh. There have been postings about doing this on this forum previously.

Glenn
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Old   June 11, 2003, 11:29
Default Re: How do you think CFX-Build?
  #6
Carola
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Hi David!, you have to separate the case in diferents sections (1000m is too large!), at the same time you need to locate de hole in a ring which belong to the tube. I had the same trouble !.

Take Care

Carola
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Old   June 11, 2003, 21:10
Default Re: How do you think CFX-Build?
  #7
David
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I really appreciate your help.

I tried to use Patran (in CFX 5.6) to descretize the geometry. Finally I got four domains in the problem. This time errors comed up in Solver. It says:

</n> ERROR #004100018 has occurred in subroutine INMES. | Fatal overflow in linear solver.

</n> I know the aspect ratio for the element is 0.05/10=0.005. Can anybody tell me whether large aspect ratio cause overflow?

Thanks!

David
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Old   June 12, 2003, 12:38
Default Re: How do you think CFX-Build?
  #8
Robin
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Not likely, as this is not that large an aspect ratio. Check your boundary conditions and verify that the mesh is in the right units (check dimensions in Post).

Robin
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Old   June 13, 2003, 16:32
Default Re: How do you think CFX-Build?
  #9
David
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Hi,Carola,

Thank you! Did you mean that I can divide the whole geometry along the center of the drill hole into several sections, for example, every 100 m/section.

Regards!

David
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