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-   -   a hole in my structure after meshing a nozzle (http://www.cfd-online.com/Forums/cfx/21647-hole-my-structure-after-meshing-nozzle.html)

Ho September 27, 2005 05:53

a hole in my structure after meshing a nozzle
 
1. For 2D geometrical divergence nozzle, firstly draw 4 points, (0,0,0), (0,2,0), (5,3,0) (5,-1,0). then use " curve command" to get 4 curves. Finally, use " surface command from 2 to 4 curves" to get a simple 2D divergence nozzle.

2. for meshing, set "global element factor=1" ,global element seed size ( 0.1 or 0.5). 3. use " mesh Tet" and default setting. The result shows that it has a hole in my strture.

Could someone help me?

Myron September 27, 2005 08:41

Re: a hole in my structure after meshing a nozzle
 
Tet (tetrahedral) elements are 3-D elements, thus will not work on 2-D geometry. You'll need to mesh with Triangles in 2-D. Try Mesh > Mesh Shell > Patch Independent (v5.1 nomenclature). You want to use the patch-independent surface mesher. It basically runs the Octree Tet mesher, but only saves the surface triangles.

Ho September 27, 2005 10:05

Re: a hole in my structure after meshing a nozzle
 
Ths for your suggestion. I use ICEM CFD 4 to make the structure and meshing. Unfortunately, I cannot find the" 2D-triangular mesher", but the" set mesh surface size". Ths.

Myron September 27, 2005 13:22

Re: a hole in my structure after meshing a nozzle
 
Try Meshing > Surface Mesh > Patch Independent Mesh

Ho September 28, 2005 03:20

Re: a hole in my structure after meshing a nozzle
 
Hallo.

Thanks for your suggestion. however, I am not sure if my version is different from yours. I use ICEM CFD 4.0. I choose Mesh>> Set surface mesh size>> to set element size, width, height, ratio,.... But I didn't find "any command" to mesh my structure. So I try to use " mesh Tet", which you talked to me is for 3D. It seems unreasonable to use this, but I cannot find other command for meshing my structure. Another question is I see no "Patch Independent Mesh". But there is another command, repair mesh>> fix hole when I am requested to repair the structure.

Myron September 28, 2005 10:38

Re: a hole in my structure after meshing a nozzle
 
The oldest version I have is 4.3. In 4.0 - apparently there is no strictly surface meshing. You'll have to go to a newer version. Or build a 3-D structure, mesh that, then throw away what you don't need.

Around 4.1 or 4.2 - there was a button in the Tetra mesher to "Save all Triangles" - which would do what you want - but still that's newer than your version.

The current version is 10.0.

Ho September 30, 2005 04:42

Re: a hole in my structure after meshing a nozzle
 
Hallo,

I draw a 3D hollow divergence nozzle with ICEM 4.2. Then I use Tet Mesh to mesh my structure. It is lucky that this time it does not show a hole in my structure. However, when I tried to write the file to CFX 5, an error messag, " running ICEM CFD/ CAE Interface vers. 4.2.6 "and extra arg: **.msh ,happened. what did that mean? Is the file after meshing file. msh or file.uns? and when I tried to import mesh from ICEM in CFX pre., it showed that the format is not compatible with CFX. What is wrong? Thank you .

Myron October 3, 2005 08:33

Re: a hole in my structure after meshing a nozzle
 
Maybe you should contact your ICEM CFD support.


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