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-   -   assemble the mesh (http://www.cfd-online.com/Forums/ansys-meshing/72049-assemble-mesh.html)

feixiangniao January 23, 2010 21:32

assemble the mesh
 
Hi,everyone.:)

when i use the Icem_cfd, i can assemble the mesh. Or i can open the other mesh in my project, i can choose the merger option. So i can mesh the complex geometry by use of the merger option.

But how to merger the part-mesh and what is the rule ? i think the rule is the global coordinate system .
And how can i make sure of the sufficient precision in the interface when i assemble the mesh so that i can obtain a good result in the cfx-post ?

PSYMN March 15, 2010 21:34

Merge or Concatonate?
 
Yes, the merge assumes that the location will be based on the global coordinate system.

However, you can move the mesh around if you need to (find the transform option). You can translate, scale, rotate, mirror, etc. Selecting the mesh is easier if everything is nicely broken up into parts.

However, the "Merge" option when you load a mesh (as opposed to replace), is really just merging the files. It doesn't merge anything at a node for node level. If you want to do that, you need to go into "Edit Mesh => Merge => Merge Meshes. You would then select an interface part and the merging would happen. It is a very robust merge tool, but their are certain rules which I have gone thru several times on CFD-Online. You can find an older post.

As for tolerance, that depends. If you want to actively merge the mesh node for node, then that probably has a tolerance around 1/5th the element size... but it is really based on the element part names and is pretty robust if the perimeter is well projected. I find the easiest way is to start from the same geometry file and break it up... Then everything is using the same coordinate system and the interface surfaces are in exactly the same location on both sides... I never have tolerance problems when I start from a single model.

If you are not intending to actually merge the nodes, then the tolerance is really a solver concern...

If the nodes already line up and you just want to merge them automatically, you can do a "Merge with a tolerance"...

feixiangniao March 20, 2010 03:39

Quote:

Originally Posted by PSYMN (Post 250158)
Yes, the merge assumes that the location will be based on the global coordinate system.

However, you can move the mesh around if you need to (find the transform option). You can translate, scale, rotate, mirror, etc. Selecting the mesh is easier if everything is nicely broken up into parts.

However, the "Merge" option when you load a mesh (as opposed to replace), is really just merging the files. It doesn't merge anything at a node for node level. If you want to do that, you need to go into "Edit Mesh => Merge => Merge Meshes. You would then select an interface part and the merging would happen. It is a very robust merge tool, but their are certain rules which I have gone thru several times on CFD-Online. You can find an older post.

As for tolerance, that depends. If you want to actively merge the mesh node for node, then that probably has a tolerance around 1/5th the element size... but it is really based on the element part names and is pretty robust if the perimeter is well projected. I find the easiest way is to start from the same geometry file and break it up... Then everything is using the same coordinate system and the interface surfaces are in exactly the same location on both sides... I never have tolerance problems when I start from a single model.

If you are not intending to actually merge the nodes, then the tolerance is really a solver concern...

If the nodes already line up and you just want to merge them automatically, you can do a "Merge with a tolerance"...


:)Thank you very much ! i will study it !


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