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Meshing a pipe with a hole

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Old   May 17, 2011, 11:43
Default Meshing a pipe with a hole
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KJ Lee
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So I exported a surface CAD of a pipe with a hole. I exported it as a parasolid and it seems to work perfectly fine. I am new to ICEM so I am getting sort of confused on this.

I can create a pretty good hex mesh using O-grid blocking strategy, but my concern is making a separate mesh for the hole in the pipe. I am going to export this to fluent, and I need to specify the boundary layers (the hole) and the inlet, outlet of the pipe.

My question might be kind of confusing but any help would be appreciated.
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Old   May 18, 2011, 02:40
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You need to put the Blocks inside the hole in a saperet part, then you will have saperete mesh fro Hole and Pipe.
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Old   May 18, 2011, 11:53
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Do you mean you have a pipe (a cylinder), with a circular patch on the curved side of it that is your inlet? You just need to associate the face with the circle... To do this, make sure you split it out (so you have edges to work with) and then associate the appropriate edges to the perimeter of the hole. The face is automatically associated to the PART of the hole (hopefully a PART you named INLET).

You may also want to add an Ogrid for this hole. Select the block immediatly inside the model (or two or three blocks in that direction if you want). Also select the face of the INLET so the Ogrid will pass out that way. Apply.

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Old   May 18, 2011, 16:44
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Hi thanks for the help!
I tried your suggestion but I am pretty convinced I am doing something wrong.
I created the first block to associate with the tiny inlet, then merged with a second block that is associated with the bigger inlet and the outlet. I also added an o grid for the tiny inlet and the outlet. The result is in the picture below.. I dont quite understand why it's so irregular...

thanks!
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Old   May 18, 2011, 17:01
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It looks like you have two separate blockings (maybe I am just misunderstanding the image)... It looks like you have one for the pipe and one for the hole (The edges for the pipe don't seem to connect with the hole, but rather overlap).

You should have one blocking and then split that blocking to capture the hole...
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Old   May 18, 2011, 17:08
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I tried using only block and splitting it. I created the ogrid for the tiny inlet first, then for the big inlet to the outlet. The resulting mesh seems very irregular to me.
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Old   May 19, 2011, 00:08
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Quote:
Originally Posted by leekj92 View Post
Hi thanks for the help!
I tried your suggestion but I am pretty convinced I am doing something wrong.
I created the first block to associate with the tiny inlet, then merged with a second block that is associated with the bigger inlet and the outlet. I also added an o grid for the tiny inlet and the outlet. The result is in the picture below.. I dont quite understand why it's so irregular...

thanks!
Hi Lee,

Firstly this approach of creating different blocks and then merging them is not appropriate. Build a block , split it accordingly and make necessary associations. Regarding the O- grid thing , try making a single O-grid at a stretch rather than going for separate O-grids. You can select all the blocks at once and then select the faces at the smaller inlet, bigger inlet and the outlet. The O - grid can then run through as desired.

In case you still have problems like some negative quality elements it may be because of the misalignment of some internal O - grid vertices. So then you may want to align them properly and you can even play around with the O - grid offset
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Old   May 19, 2011, 09:31
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Right, you should create the Ogrid for the cylinder all at once... But then you can add a second ogrid to capture the inlet boundary as I described earlier.

Try some tutorials to get going faster.

This you tube vid may also help...

http://www.youtube.com/ansysinc#p/u/9/9h97FvWJPcY

Simon
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Old   May 19, 2011, 13:34
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thanks for the help!
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