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-   -   [ICEM] Error in Hybrid Mesh (http://www.cfd-online.com/Forums/ansys-meshing/71383-error-hybrid-mesh.html)

ali987 December 29, 2009 07:04

Error in Hybrid Mesh
 
Hi everyone,

We I merge Hex and tetrahedral regions following errors occurs:

I am trying to include edge 95 98 but vertex 95 isn't even in the region 1
error including edge 95 98
could not include quad
.
.
.
I am trying to include edge 4 7 but vertex 7 isn't even in the region 1
I am trying to include edge 6 5 but vertex 5 isn't even in the region 1
unable to include quad 2 (4 7 6 5)


but when I check the mesh(just by looking at it), it seems all elements are correct. what's that error??? It's very important for me to have a "pure" hex mesh which connect to the pure Tetrahedral meshes with pyramidal element. I mean I don't want to have, for example, tetrahedral elements in hex region.

Regards,

PSYMN January 1, 2010 15:22

The rules...
 
Tet Hexa merge is actually very robust in ICEM CFD. Try the tutorial for practice, but basically, the interface region can be any shape or curved or even be multiple separate interfaces. However, there are two rules for Hex-Tet merge that must be followed. I will try to make these clear, even if the error messages are not...

1) The entire surface of the interface parts must be used to merge. So if you are merging a Cylinder (circle) to a Cube (square), make sure the overlap (circle on both sides) are the interfaces and do not use the square side which is not completely shared by the cylinder.
2) The perimeter of the interface must be followed by both the Hexa and Tetra mesh… Line elements must be formed around the perimeter (or you get this error message). The tetra side is easy with the Octree tetra mesher, it just means you must have perimeter curves and the Octree mesh will naturally fit to the curves and create these line elements. If you imported the tetra mesh, you may need to extract these line elements or even fit it to the perimeter of the interface. It is usually easier for users to forget to generate these critical line elements on the Hexa side. ICEM CFD Hexa blocking is naturally patch-independent. If you want to explicitly extract a surface patch with line elements at the perimeter, you must associate the edges with the curves at the perimeter of the interface. Even if that edge and curve already appear “aligned”, make sure you associate them or you won’t get line elements and you will get this cryptic error message…

itsme_kit March 20, 2014 13:46

1 Attachment(s)
Quote:

Originally Posted by PSYMN (Post 241240)
Tet Hexa merge is actually very robust in ICEM CFD. Try the tutorial for practice, but basically, the interface region can be any shape or curved or even be multiple separate interfaces. However, there are two rules for Hex-Tet merge that must be followed. I will try to make these clear, even if the error messages are not...

1) The entire surface of the interface parts must be used to merge. So if you are merging a Cylinder (circle) to a Cube (square), make sure the overlap (circle on both sides) are the interfaces and do not use the square side which is not completely shared by the cylinder.
2) The perimeter of the interface must be followed by both the Hexa and Tetra mesh… Line elements must be formed around the perimeter (or you get this error message). The tetra side is easy with the Octree tetra mesher, it just means you must have perimeter curves and the Octree mesh will naturally fit to the curves and create these line elements. If you imported the tetra mesh, you may need to extract these line elements or even fit it to the perimeter of the interface. It is usually easier for users to forget to generate these critical line elements on the Hexa side. ICEM CFD Hexa blocking is naturally patch-independent. If you want to explicitly extract a surface patch with line elements at the perimeter, you must associate the edges with the curves at the perimeter of the interface. Even if that edge and curve already appear “aligned”, make sure you associate them or you won’t get line elements and you will get this cryptic error message…

Hi PSYMN

I got the same problem now

I attach a pic to show the interface I built

The mesh includes Hex, tetra and prism (where located at the bottom for boundary layers)

How can I solve this problem?

Really appreciate your help

Thanks in advance


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