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[ICEM] Merge meshes with internal wall

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Old   February 20, 2013, 04:14
Default Merge meshes with internal wall
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I have 2 projects : tube and cube (.tin .blk .uns .prj attached).

The inlet is located at the down part of the tube, and the outlet at the top part of the cube. The top of the tube is open into the cube. And the walls of the tube which are inside the cube (almost half of the tube) are internal wall.

My goal is to merge those 2 meshes, and at the end, to have only 1 volume (fluid). I opened ONLY the cube_only.uns and tube_only.uns files, and I merged the nodes the wall of the tube which is inside the cube with the correspondant part, and deleted one of the interface. Next, I tried to specify the remaining tube wall (which is inside the cube) as an internal wall. But this option is gray tint.

How am I sure that this interface will be considered as an internal wall by my solver ? (let's take as an example FLUENT) Was it the right way to do it ?
I tried to specify one of the interface as an internal wall when I created the blocking, but after I imported the .uns file, the option was gray tint.
Attached Files
File Type: zip CUBE_ONLY.zip (36.8 KB, 22 views)
File Type: zip TUBE_ONLY.zip (29.7 KB, 9 views)

Last edited by BrolY; February 20, 2013 at 04:40.
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Old   February 20, 2013, 05:31
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You can merge blocking as well.


You want to keep the interface (2 and 3) ?
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Old   February 20, 2013, 05:38
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What do you mean by 2 and 3 ?

Attached the merge I've done as I explained in the previous post. I merged nodes (Edit Mesh -> Merge Nodes) of INTERF_WALL and INTERF_WALL_01, and then delete INTER_WALL_01.

I don't know if Fluent (or another solver) would consider INTERF_WALL as a separation between the fluid from the tube and the cube because I can't specified INTERF_WALL as internal wall.
Attached Files
File Type: zip MERGE.zip (38.8 KB, 7 views)
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Old   February 20, 2013, 05:58
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You want the internal wall as interior or wall? Int wall is really used to define the wall.

You are merging two hexa meshes? Which I dont think is good idea. Better idea would be to merge blocking and you have the full control over everything.

If you want to get the int wall option, do this!!!

1. Load mesh

2. Edit > Mesh >>> Facets

3. Define int-wall in part mesh setup
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Old   February 20, 2013, 06:06
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Please find enclosed fluent file. Do you want mesh like this?
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File Type: zip MERGE.zip (38.8 KB, 11 views)
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Old   February 20, 2013, 06:16
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I just want the solver to understand that this wall is a wall, not shells which should not be here (2D thickness). So the fluid can't go throught this wall.
I've done that only with Tetra and I know that the option "int wall" tells the mesher (basically) "it's a wall, dont delete those shells". After I can specify those shells as a wall when I export my project.
My problem is I'm facing a mesh created by a merging of 2 hexa meshes and 2 interfaces at the end. So I don't know if merging the nodes, and deleting one of the interface would led to what I'm looking for. If I merge nodes, would it connect the volume mesh from the 2 sides of the interface and at the end, the solver would consider the shells between the volume as a wall ? Or would it consider the shells as an error and just delete them ?

That is just a simple example, but my geometry is more complicated.
Merging blocking is a good idea, but I have something like 8 blocking.
I've noticed that at some point, it's really "heavy" to ICEM to handle it (crash, slow-down ..).

So merging unstructured meshes appeared to be the best solution.
And I want to keep Hexa, not to go with facets ... because facets means to convert your mesh to tetra, am I right ?
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Old   February 20, 2013, 06:21
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Quote:
Originally Posted by BrolY View Post
So merging unstructured meshes appeared to be the best solution.
And I want to keep Hexa, not to go with facets ... because facets means to convert your mesh to tetra, am I right ?
Here mesh > Facets is used to extract the geometry from underlying mesh. and once you have geometry you can specify wall as int wall in part mesh. May be in background triangulation is used to make the surfaces but it does not mean that you are converting your hexa mesh into tetra.

I find this thread interesting.
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Old   February 20, 2013, 06:31
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Ok, so ICEM needs the geometry to create internal wall ? It means that when you export your mesh with internal wall, you always need to have the geometry file in your project, and not only the mesh ?

I'm still wondering if it would works. If the process merge nodes + delete one of the interface would not have created problems.

Thanks for your help
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Old   February 20, 2013, 09:11
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Did you check the fluent file I just uploaded?
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Old   February 20, 2013, 09:23
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There are only .prj and .uns file.

That looks like to the projet I've uploaded in my 2nd post. How did you proceed at the end ?
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Old   February 20, 2013, 09:37
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Oh wrong file .
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File Type: zip fluent.zip (62.0 KB, 6 views)
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Old   February 20, 2013, 11:10
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@broly, i understand what you want.
I once was wondering if this was doable, but never had the chance to test it out.
Now that i did,i am missing something because it cant be so easy...
When i opened your merged project where you have merged the two meshes. You left only the inter_wall. You want that to be a wall in the output menu, i specified inter_Wall as wall. it worked and it created a shadow in fluent. isn't it what you want ??
I guess no...
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Old   February 20, 2013, 11:15
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i'm not really familiar with Fluent, so what does "shadow" mean ?
Is it a 2D wall surronded by fluid (but keeping them from being connected) ? If yes, that's what's I'm looking for !
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Old   February 20, 2013, 11:16
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For internal wall (inside fluid) you have two sides. one is wall and second its shadow (other side)
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Old   February 20, 2013, 11:21
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So that's good I think. For each part of the fluid, it's a wall.

Also, it means that I don't need to define the INTERF_WALL as an internal wall.
The "internall wall" option is only for the mesher. Am I right ?
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Old   February 20, 2013, 11:22
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yes it is a 2d wall surrounded by a fluid. i guess fluent makes a shadow of that wall because you have elements in both side of the wall. where you usually have only one side...
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Old   February 20, 2013, 11:32
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I feel like you are planning to do multiple separated blocks, and merge them... isn't easier to do one blocking ?
for a perfect merge, the node should be in the exact location... did you create a sub-topo for this one ?
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Old   February 20, 2013, 11:33
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Thank you guys !
I guess we all have learned something today
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Old   February 20, 2013, 11:39
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Quote:
Originally Posted by BrolY View Post
So that's good I think. For each part of the fluid, it's a wall.

Also, it means that I don't need to define the INTERF_WALL as an internal wall.
The "internall wall" option is only for the mesher. Am I right ?
You have to explicitly tell ICEM to treat extended surface as wall, otherwise it will not recognise it and think it is by error and removes the shell elements.

For tetra mesh, you define it in part mesh setup, whereas in Hexa it is defined by making the face to surface association explicitly
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Old   February 20, 2013, 11:41
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Quote:
Originally Posted by diamondx View Post
I feel like you are planning to do multiple separated blocks, and merge them... isn't easier to do one blocking ?
for a perfect merge, the node should be in the exact location... did you create a sub-topo for this one ?
Sub topo is much better idea than merge
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