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famerfamer May 29, 2011 23:02

Mesh issues
 
2 Attachment(s)
Hi Guys,

I just meshes a bundle (full of pipes) but the skewness angle are around 95. Those bad cells are located on the walls outside the bundle as illustrated in the picture. The geometry is also shown in the picture.

What should I do? I've refined the whole bundle by decreasing the base size of the mesh a lot (four times, every time decreasing by a ratio of 1.3). The problem is still there.

Thanks for your help!

Famerfamer

alastormoody11 May 30, 2011 06:34

Instead of changing the base size which will lead to a large increase in the cell count, you can try putting the pipes creating problems in different boundaries by splitting them interactively and then set smaller custom surface sizes, so that those areas are captured by means of local refinement.

famerfamer May 31, 2011 15:31

Quote:

Originally Posted by alastormoody11 (Post 309755)
Instead of changing the base size which will lead to a large increase in the cell count, you can try putting the pipes creating problems in different boundaries by splitting them interactively and then set smaller custom surface sizes, so that those areas are captured by means of local refinement.

Thanks for your reply.

Is there any difference if I use volumetric control to only refine those walls where those bad cells are located? I mean to use a very thin block to cover those walls. But I'm not sure if only by refining walss the problem can be solved. How do you think?

Thanks,

Famerfamer

famerfamer May 31, 2011 17:02

Quote:

Originally Posted by alastormoody11 (Post 309755)
Instead of changing the base size which will lead to a large increase in the cell count, you can try putting the pipes creating problems in different boundaries by splitting them interactively and then set smaller custom surface sizes, so that those areas are captured by means of local refinement.

BTW, to creat boundaries, I need to split the whole boudary by patch which will kill my computer almost cuz there will be too much boundary generated then. Currently I had 67Million polyhedral cells for the mesh. So you can see it's not a small one. Thanks.

famerfamer May 31, 2011 17:53

Quote:

Originally Posted by alastormoody11 (Post 309755)
Instead of changing the base size which will lead to a large increase in the cell count, you can try putting the pipes creating problems in different boundaries by splitting them interactively and then set smaller custom surface sizes, so that those areas are captured by means of local refinement.

Can I use 'split boundary by patch' to define a boundary locally (like only the problematic areas? )instead of split the whole boundary of the geometry into pieces of patches?

Thanks for you help.

Famerfamer

famerfamer June 1, 2011 10:38

You're right... I try to refine those walls and there has already been 11Million surface meshes generated which is toooo large for a volume mesh...

Help... Does anyone have a good idea?

daveatstyacht June 8, 2011 21:41

You could try repairing the base surface either with the surface wrapper or manually (it's a pain, but sometimes and hour of geometry clean up can save you a week of meshing). A lot of times the a poor underlying geometry can make a mess of things (trailing edges on wings, stl files, etc). The manual repair feature is found by right clicking on the import tab of the "representations" directory. Hope this helps


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