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-   -   Structured mesh in ICEM for rectangular channel (http://www.cfd-online.com/Forums/ansys-meshing/73340-structured-mesh-icem-rectangular-channel.html)

Josh March 4, 2010 23:50

Structured mesh in ICEM for rectangular channel
 
Hi -

We are trying to create a structured mesh in a 2D channel of dimensions 8 x 0.2.

Although we have tried the basic geometry creation and meshing tutorials found here (http://www.kxcad.net/ansys/ANSYS_ICE...rial/index.htm), but without success.

If anyone could help us create a very simple 50x10 mesh, or point us to a good source for basic geometry creation / meshing tutorials, we would be eternally grateful.

Josh March 9, 2010 18:30

Maybe I should be more specific.

After trying the tutorials, we want to know if blocking is necessary, or if a mesh can simply be created without resorting to blocking.

I have created some structured hexahedral mesh elements in the > Edit Mesh tab. Here is a picture of two of the elements on the bottom of the rectangular prism, and one on the top:
http://picasaweb.google.com/lh/photo...eat=directlink

There should be 10 mesh elements along the height (y), 1 element along the width (x), and 50 along the length (z).

I cannot seem to find help for even a task this simple. I have been working on unstructured meshes in the CFX built-in meshing utility since last summer, but I am relatively new to the ICEM mesher and am struggling with simple tasks.

Please don't think I haven't tried solving this without researching extensively. Any help would be greatly appreciated.

rikio March 10, 2010 02:51

1 Attachment(s)
I am not sure I get your idea or not.
If you want to mesh the domain without blocking, Surface Mesh would be the right choice for you.
1. Create the geometry of 8 x 0.2. There will be one surface, four curves and four points.
2. Set the global mesh size to a proper value, such as 0.2 in your case. Mesh/Global Mesh Setup
3. Set the number of nodes of two long curves to 51, and 11 for the two short. Mesh/Curve Mesh Setup
4. Mesh the surface by checking the option of Overwrite Surface Perset/Default Mesh Type in the Mesh/Compute Mesh tab. Mesh will be obtained after you click on the compute button.

The attachement is the mesh I got. For your reference.

Josh March 10, 2010 21:10

Thanks for the help.

Say I have a 3D geometry, a 0.8 x 0.1 x 0.1 duct, and want the same mesh, but extruded with the third dimension being only one element deep. I want to run the simulation in CFX, so a 3D duct is required.

When I try the above steps with surface meshing, I obtain the following mesh:
http://picasaweb.google.com/lh/photo...eat=directlink

I then tried changing the surface mesh type to "all quad" and obtained a nicer mesh (side and front views):
http://picasaweb.google.com/lh/photo...eat=directlink
http://picasaweb.google.com/lh/photo...eat=directlink

This is the right structure - a 50 x 10 x 1 mesh. However, upon closer inspection, we see that the mesh is only on the surface, not within the volume:
http://picasaweb.google.com/lh/photo...eat=directlink

This makes sense, since we were only doing a surface mesh. I need to somehow extrude this same surface mesh as a volume mesh (one element deep). I've tried several methods - extruding, for example - but to no avail.

Help would be greatly appreciated.

On a side note, please don't think I'm being lazy and avoiding the tutorials. I'm having issues with the ANSYS customer portal (where I normally get the CFX tutorials), this assignment is due Friday, and nobody in my department knows how to use ICEM!

rikio March 11, 2010 21:25

Sorry, I can't open your links.
But maybe you don't check on the volume option in the mesh tree. Only shell mesh was displayed on default.

Josh March 12, 2010 15:53

That's strange about the links. It's public domain.

Well, after talking to an ANSYS employee, it seems that the way we went about creating the structured mesh (creating a surface mesh and extruding it one element deep) can cause problems in Pre, which it did. We couldn't view any of the parts we had created and, hence, we couldn't create boundary conditions.

Seems the only proper way to do this is with blocking, which I've studied in the online tutorials (2D pipe and 3D pipe), but always seem to encounter problems, particularly when trying to move the vertexes of the block onto the geometry.


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