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-   -   [GAMBIT] Forcing a new mesh to conform to a previously generated mesh (http://www.cfd-online.com/Forums/ansys-meshing/104055-forcing-new-mesh-conform-previously-generated-mesh.html)

pmdelgado2 July 2, 2012 12:27

Forcing a new mesh to conform to a previously generated mesh
 
1 Attachment(s)
The problem that I am really working on is much more complicated, but I find it is easier to explain it with a simpler instance.

http://www.math.utep.edu/faculty/pmd.../mergemesh.png

Suppose I imported a mesh from a file into GAMBIT (vertical rectangle). I need to attach a new geometry at the top of the original geometry (horizontal rectangle) and mesh it such that the new mesh coincides with the first mesh at their interface. In other words, I want the second mesh to recognize the existence of the nodes in vertical mesh where they intersect, so that the new mesh will use these nodes.

Obviously for this simple case, I know that I could unite the two faces together. However in my actual problem, the imported (meshed) geometry is TOO complicated to both unite and remesh. Also, in this picture, there are only three nodes that connect the two geometries. In my actual problem, there are many of them, and it is extremely cumbersome to select them one by one or even in groups.

How can I force my new geometry's mesh to conform to the imported mesh using Gambit?

-mAx- July 3, 2012 00:40

The two topologies have to match together, in other words you need to connect them.
In your simple case, you need to split the horizontal rectangle with the 2 upper vertices from vertical rectangle.
Then connect the 2 superposed edges (upper edge from vertical rectangle)
Once it is done, the 2 rectangles are connected and you can mesh your horizontal rectangle.
The 2 meshes will match each other.
I am also handling complicated geometries, and I "glue" old mesh with new one.
But I don't import mesh. I open old dbs, then delete what I don't need, I import new topology (step), finally I do the procedure I explained...
No problem

Far July 3, 2012 00:52

You can also use non conformal interface in fluent to connect. That would be easy method for complex cases.

pmdelgado2 July 3, 2012 11:10

@Far: Can you describe how to create a non-conformal interface?

diamondx July 3, 2012 11:18

let's suppose you want to merge two bodies, of curse they need to share a same surface. you will load the first mesh in fluent. then you click on mesh - zone - append case file and select the second body.
You will then click on "mesh interface", give a name to you interface and select the surfaces above and click on apply.

pmdelgado2 August 22, 2012 16:24

How?
 
Sorry for the long delay in my reply. I saw in your previous message that I will need to "connect" two superimposed edges. Could you elaborate on this? How do accomplish this on gambit?

Quote:

Originally Posted by -mAx- (Post 369423)
The two topologies have to match together, in other words you need to connect them.
In your simple case, you need to split the horizontal rectangle with the 2 upper vertices from vertical rectangle.
Then connect the 2 superposed edges (upper edge from vertical rectangle)
Once it is done, the 2 rectangles are connected and you can mesh your horizontal rectangle.
The 2 meshes will match each other.
I am also handling complicated geometries, and I "glue" old mesh with new one.
But I don't import mesh. I open old dbs, then delete what I don't need, I import new topology (step), finally I do the procedure I explained...
No problem


-mAx- August 27, 2012 03:23

did you fix your problem?

pmdelgado2 August 27, 2012 09:21

Not yet...
 
I tried, but I'm not quite sure what you mean by "connecting the two superimposed edges". How do I do this on gambit? (i'm using version 2.4.6)

Quote:

Originally Posted by -mAx- (Post 378815)
did you fix your problem?


-mAx- August 27, 2012 09:28

let say you have 2 cubes with one "common" face
to be sure that the 2 volumes are connected, you can try to move (not copy) one volume. If it is failed, then both volumes are connected (and gambit will explain in the error, that your entity is connected to another one)
If it is successfull then you can imagine that you have 2 superposed surfaces (common faces), and you will be able to connect them with the connect-face tool

pmdelgado2 August 27, 2012 10:02

It makes sense, but...
 
The concept makes sense, but the implementation is what I'm struggling with. Where do I find the command to 'connect' two faces together? Other than the union operation, I'm not sure how else to connect them?

Quote:

Originally Posted by -mAx- (Post 378898)
let say you have 2 cubes with one "common" face
to be sure that the 2 volumes are connected, you can try to move (not copy) one volume. If it is failed, then both volumes are connected (and gambit will explain in the error, that your entity is connected to another one)
If it is successfull then you can imagine that you have 2 superposed surfaces (common faces), and you will be able to connect them with the connect-face tool


-mAx- August 27, 2012 10:05

http://aerojet.engr.ucdavis.edu/gamb...connect_discon

pmdelgado2 August 27, 2012 14:33

Error
 
Thanks for your help. I looked at the tutorial and found the connection button that I was looking for. I also tried it on a 2D geometry (connecting edges together) with the mesh/geometry shown in the image I posted earlier. I selected edge 1 (top of the vertical rectangle) and edge 7 (the bottom of the horizontal rectangle) and applied the following command on gambit:

edge connect "edge.1" "edge.7" virtual

I then received the following error:

ERROR: The connected vertices include vertex.7 which has a short edge edge.7 attached to it (edge of length close to connect tolerance). In order to avoid degenerate edge construction include vertex vertex.8 (the other end vertex at the edge) in the connect. (Enable connect with degenerate edge removal.)

Am I approaching this correctly?
Let me know your thoughts.
Thanks,
Paul

-mAx- August 28, 2012 00:53

edges have to be exactly the same: in your case, you need to split the bottom edge (horizontal rectangle) with respect of top edge (vertical rectangle)
This operation will split the top edge in 3 segments (edges). The middle one will be exactly the same as top edge (but will not belong to verticle rectangle).
Then you will have 2 superposed edges, which you can connect


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