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RodriguezFatz October 29, 2012 09:45

Aligning Edges?
1 Attachment(s)
Dear All,

I work a lot with pipeflows and have a perseverative problem.
My blocking generally looks more or less like the attached picture.
Attachment 16453
In the curved regions, I need to insert these additional splits (blue arrow). Otherwise I get negative volumes, cripples cells etc.
Now, when I "spline split" the edges to get them closer to the actual pipe in the bends (orange arrow), I can not align these points to the surface. All I do is "by hand", which is not really precise to my taste (especially in 3d).
Is there any better way to align edges to a pipe? Also the inner edges of the O-grid cause the same trouble.

Thanks in advance.

energy382 October 29, 2012 10:21

No need to split edges. Just extrude faces along curve and insert two or three additional splits.

If you use these split edge function, you've to adjust the interior edges by "link edge".

usually, icem projects edges to nearest surface (if not associated in another way). if you use this split edge function (linear or spline), the mesh will follow exactely this shape instead of projecting to nearest surface. It's always better to associate edges to geometry (or any other association), as this split edge function is a more "tricky" thing, for example to improve cell angles in a very complex topology

RodriguezFatz October 29, 2012 10:27

Hi! Thank you for your reply.
What do you mean by:

Originally Posted by energy382 (Post 389097)
Just extrude faces along curve


energy382 October 29, 2012 10:42

blocking/create block/extrude faces/along curve

Just select faces from your o-block and extrude them along your curved line (repesenting the curved part of your pipe surface).

If you provide .tin-file, I can clarify my thoughts

diamondx October 29, 2012 12:56

i have dealt recently with curved tubes, if you go with extrude along curve, do it step by step, otherwise you will get negative volumes cells. remove all associations for the curves, then associate only the one that they seem difficult for icem to associate, (don't know if was clear).
Suddenly i have an idea i wanna try, please if you can share the tin...

Far October 29, 2012 13:05

Hits from Ansys official presentation :

RodriguezFatz October 30, 2012 06:04

1 Attachment(s)

Originally Posted by energy382 (Post 389104)
blocking/create block/extrude faces/along curve

Just select faces from your o-block and extrude them along your curved line (repesenting the curved part of your pipe surface).

If you provide .tin-file, I can clarify my thoughts

I create the geometry file using DesignModeler and use the "Workbench Readers" to import the geometry to ICEM. Right now the only curves are inlet and outlet "circles" and a few intermediate circles. I never used the "extrude faces" command, but is it correct that I need to create a curve (maybe in DM) along the pipe and than use it as the "Extrude Curve" ? What is the best location for that curve, in the middle of the pipe or somewhere at the wall?

It works. Thank you very much!
Attachment 16499

RodriguezFatz October 30, 2012 08:27

1 Attachment(s)
Next Problem: When I continue the extrusion, (starting with the picture above) I get the error message "Extrusion of faces failed".
Any ideas?
Attachment 16500

Far October 30, 2012 09:41

Wow. It is failing at point of inflation ;)

Far October 30, 2012 10:01

1 Attachment(s)
done. Needs following steps

1. Use extrude along curve first until it fails.

2. If needed merge some curves and avoid this process when curve is changing its direction (needs confirmation from Simon)

3. If along curve extrusion fails then use fixed distance for very small distance and then continue using the extrude along curve. This block can deleted and vertices can be merged to maintain the connectivity.

4. Number of layers 5 to 10

5. O-grid should be created in last.

This is working for me on your geometry. See this image :

diamondx October 30, 2012 12:34

icem handles the extrusion better in the unstructured level... tried it yesterday on a 90 curved tube and it worked

RodriguezFatz October 30, 2012 14:31

Thank you Far, you are the best!
Just for the future: How can I create a geometry, that can be swept without this workaround? I mean, this pipe seems to be pretty simple, what's the problem here?

Far October 30, 2012 14:39

Problem is that blocks are straight with rectangle shape and ur task is to get of shape of the underlying geometry. ICEM has automatic capability to project the faces to the nearest surface but that should be within some limits.

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