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-   -   Non-conformal mesh (http://www.cfd-online.com/Forums/fluent/29386-non-conformal-mesh.html)

Christian February 20, 2002 05:43

Non-conformal mesh
 
Hi.

Is it possible to make a non-conformal mesh in Gambit (I have looked in the manual, but I have not found it yet). If yes, can I get some hints ?

Cheers Christian

Erwin February 21, 2002 15:29

Re: Non-conformal mesh
 
You can't do it all with Gambit as far as I know. Normally you create the two zones independently in Gambit, from which you generate two mesh files. Note: the nonconformal interface should have 'interface' as boundary type. Then they need to be read into TGrid and you can then write it out as one grid file. I believe it can also be done without TGrid: in your Fluent directory there should be a folder 'Utility' containing another one called 'TMerge2.1'. This should also allow you to create one grid from two.

Christian February 22, 2002 04:03

Re: Non-conformal mesh
 
Hi Erwin.

May I ask how to do that. If i have a simple 2D case: two boxes; one with quads=10 and one with quads=5. How should I proceed? The help in TGrid speaks of connecting layers with tets. I just want an interface between two different-sized quads.

Hope you can help.

Christian

Ale February 22, 2002 05:57

Re: Non-conformal mesh
 
Hi, you can try this way.

If you need to have two faces meshed with different element size, you can define two edges between the same vertices at the common boundary between the two faces. In this way the two faces will not have shared edges, and can be meshed separately. The two edges at the common boundary will be defined as 'interface'. When you go to Fluent, you will go to the menu Define-->grid interfaces and you will create an interface with the two edges. This will probably create some walls with no dimension, which apparently have no effect on computation (if anyone has more precise ideas about that, please tell me).

You should do this with all the 'interfaces' between different meshes in your grid.

I don't know if it is clear enough, but I hope this can help you. Feel free to ask if you need, and please tell me if you find this a correct way to make non-conformal meshes.

Bye, Ale

Erwin February 22, 2002 11:35

Re: Non-conformal mesh
 
You are right, this is a much simpler way to do this.

The dimensionless walls can be deleted if you want to(Surface --> Manage), they indeed have no effect.

The method I proposed is useful when you have different mesh files that first need to be merged. (I found that the actual command to be used is "tfilter tmerge2d" or "tfilter tmerge3d".)

This was a useful little exercise for me, I am going to use more nonconformal meshes in the future to minimize the use of tets.

Christian February 25, 2002 03:32

Re: Non-conformal mesh
 
Thanks. This tip is very usefull for me. I can minimize the use of tets and avoid long thin quads.

I think that this is the correct way, and the creation of unwanted faces seems to be because that the technique used is the same as used for moving/sliding meshes.

Cheers Christian


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