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-   -   [ANSYS Meshing] Identical meshes in symmetric bodies in multibody part. (http://www.cfd-online.com/Forums/ansys-meshing/101688-identical-meshes-symmetric-bodies-multibody-part.html)

aarvay May 10, 2012 17:16

Identical meshes in symmetric bodies in multibody part.
 
Hopefully this is a simpler problem than I think. I am attempting to model a fuel cell with a slightly complex geometry using v13.0 of the workbench and I can't seem to get an identical mesh generated on identical geometries in a single part. The bodies are identical and sweepable and I don't understand why it will not generate the same mesh on each part, and I don't know what tool i can use to force that to happen.

http://dl.dropbox.com/u/70600276/iso1.PNG
This is a simplified version of the geometry. The parts that are meshed are geometrically identical. however the meshes that get generated by sweeping are slightly different.

http://dl.dropbox.com/u/70600276/a.PNG
looking down from directly above.

http://dl.dropbox.com/u/70600276/wire1.PNG
This is a wire frame of just the top body. I swept this body so the lines overlap perfectly and on this single piece, the faces on the top and bottom line up exactly. The problem is, they don't line up with the other body...

http://dl.dropbox.com/u/70600276/wire2.PNG
When i overlay the top mesh with the bottom mesh, you can see where they seem to diverge. These bodies don't connect directly to each other, but they are in the same part connected by other parts, so eventually each interface has to be conformal. There is a total symmetry along the z-axis so there is no reason why it can't maintain the same exact cross section (in the previous picture) through the entire geometry.

Is there a way i can force the mesh to use a particular face or something sweep the whole way through multiple bodies in a single part? it doesn't seem to be possible. Anyone have any suggestions on how to mesh this part?

Thanks.

Gweher May 11, 2012 07:02

Hi Adam,

By looking at your pictures you have a certain number of parts for your fuel cell. Did you form a new part with all of these parts (did you put them inside a “global” part) or left them as multiple parts?

I’m not 100% familiar with the mesh generation within Ansys Meshing, but maybe the meshing tool starts meshing the upper “layer” from the center and the lower “layer“ from another subpart( depending on the name of your parts for instance). If you don’t assign any mesh control on the edges or faces it doesn’t surprise me that the mesh may be slightly different on both layers. If you assign some controls you may work it out (right click on mesh >sizing and select the external/internal edges for instance).

If it doesn’t work out you can maybe send me your DM geometry (.agdm) and I can have a look ;)

aarvay May 11, 2012 11:15

Quote:

Originally Posted by Gweher (Post 360566)
Hi Adam,

By looking at your pictures you have a certain number of parts for your fuel cell. Did you form a new part with all of these parts (did you put them inside a “global” part) or left them as multiple parts?

I’m not 100% familiar with the mesh generation within Ansys Meshing, but maybe the meshing tool starts meshing the upper “layer” from the center and the lower “layer“ from another subpart( depending on the name of your parts for instance). If you don’t assign any mesh control on the edges or faces it doesn’t surprise me that the mesh may be slightly different on both layers. If you assign some controls you may work it out (right click on mesh >sizing and select the external/internal edges for instance).

If it doesn’t work out you can maybe send me your DM geometry (.agdm) and I can have a look ;)


Thanks for the tips. Every body is listed under the same part. I put everything as one huge part with many bodies because its not possible to have sub-parts. I hadn't considered the name of the parts or their order in the tree to be one of the factors that determines the mesh. I'll look into that, maybe making named parts or something.

I wanted to avoid using edge size controls because the picture I posted was only a part of my total geometry, and having to put edge size controls on all of the edges would get incredibly tedious. It may be the only way to do it, but I'm hoping there is an easier way.


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