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CFX Begineer October 16, 2002 12:08

How to generate structured mesh?
 
Hi All. Could anyone tell me if I could generate a structured mesh in CFX5 (rather than unstructured mesh)? If so, please kindly let me know how to do it.

Thanks for sharing your experience.

Astrid October 16, 2002 15:53

Re: How to generate structured mesh?
 
If you do not have CFX 4, you have to wait until CFX 5.6, which will be relaesed in the first quarter of 2003.

Astrid

Holidays October 17, 2002 01:38

Re: How to generate structured mesh?
 
You can already use in "mesh mode only" the Patran Volumeshing tool to achive some structure in your mesh in CFX-5.5 and CFX-5.5.1.

cujo October 17, 2002 02:31

Re: How to generate structured mesh?
 
You can use an imported mesh, for example from Ansys (FEM) or so. Choose "Import Mesh" when starting a new database and look at the possible import formats.

CFX Begineer October 17, 2002 03:48

Re: How to generate structured mesh?
 
Thanks for your valuable inputs. I guess the current version of CFX Build (5.5.1) will not be able to generate the structured mesh for my model, right? I mean without having to import from another software.

Michael Bo October 17, 2002 07:52

Re: How to generate structured mesh?
 
You can do it now as laid out by "holidays". You should choose to work in "mesh only mode" and export the structured mesh, which has to be imported into a new database. Consult with your manual.

CFX Begineer October 18, 2002 11:25

Re: How to generate structured mesh?
 
Thanks, guys. I will try the methods you have mentioned here.

One more question. Will the solution (steady or unsteady) be different (or better in term of accuracy) if we use the structured mesh instead of unstructured mesh?

I know that unstructured mesh maybe more efficient in term of computational time required.

Thanks for any comments here.

Astrid October 20, 2002 18:22

Re: How to generate structured mesh?
 
The link between accuracy and type of mesh is not very obvious, because there are a lot of parameters that interfere. In the help of CFX 5.5.1 you can find some information on tet- versus hex-meshes, compared on a memory and accuracy basis. There you may find what you need.

Astrid

CFX Begineer October 22, 2002 08:28

Thank you
 
Thanks for your advice, Astrid. I will look at it now.

lego October 24, 2002 14:07

Re: How to generate structured mesh?
 
Hi!

> I know that unstructured mesh maybe more efficient in term of computational time required.

I do not think so. The tetrahedral mesh nodes has only 4 neighbours in comparison with the 6 neigbours of hex mesh nodes, but the volume of a tetraeder is 1/seventh of a cubic with the same edge length. So the advantage of the tetrahedral unstructured mesh is felxibility in progression of meshing, so you can mesh easily as complex geometry as you need, or use mesh controls. But if you have a simple geometry with x y and z symmetry, and a uniform mesh is OK for you, I think structured hexahedral mesh is better.

LEGO

Attention! I am a beginner too!

Robin October 24, 2002 21:49

Re: How to generate structured mesh?
 
Actually, a hex element typically has 6 neighbors, although there may be more, or less, depending on the local structure. A tet element typically has many more connections, just how many is not fixed and will again depend on local topology.

The higher connectivity in a tet mesh results in greater memory usage, which typically results in longer computation time. However, the time saved in meshing the model may make up for this.

Robin


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