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C Grid for U bend Pipe

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Old   November 13, 2009, 05:48
Default C Grid for U bend Pipe
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Need help to block a C-grid around the U bend of a pipe. Seems simple and straightforward, but i tried everything and doesn't seem to work.

Thanks
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Old   November 15, 2009, 16:30
Default Top Down...
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Look at the shape of the upipe and you can see that it is a Cblock with the central block deleted... That is a key to using ICEM CFD Hexa, use the OGRID tool to capture your overall blocking topology.

I will attach an image to illustrate the two main ways to capture this geometry... The first one, top down like a sculptor, is the best way with the ICEM CFD tools.

Try the Sphere Cube workshop to drive this principle home.

After you have done this first step to use Ogrid to capture the general topology, you will need OGrid again at the end to capture the boundary layer...
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Old   November 15, 2009, 16:31
Default Slide
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Oops, forgot to attach my slide.
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Old   November 16, 2009, 01:19
Default Thanks Simon
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Thanks a lot. The top down approach looks lovely. WIll try it.
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Old   November 29, 2010, 07:29
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hello Simon
I too have stuck in the same problem. I saw your reply but could not make out how to capitalize that "top-down topology creation". When i delete the central block, i get an L shape (without using O- grid method.)
Can you please elaborate (involved steps), how we can get 2nd & 3rd block from the 1st block & then mapping order.
Is there some pre-requisite(e.g. no. of curves along the bend..etc), that should be full-filled in the geometry for topology to work properly.
I have been trying to find out proper topology for an U bend pipe for last 4-5 days, but without success. Now it seems like..I am at the right door..!!!
Please help me ..i am in dire need.
Thanks in advance..
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Old   November 29, 2010, 14:23
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If anyone else has..some important piece of information..then plz share..!!
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Old   November 30, 2010, 01:13
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Pradeep, you need an O-grid first, and then 'delete' the central block. You will then have a U to capture your geometry. Post some pics of your blocking so we could help you better.
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Old   November 30, 2010, 01:39
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I have seen your geometry, & i m doing exactly the same problem as you have done i.e. generation of structured hexa mesh in an U bend tube. I was trying the top down topology as stated above, but couldn't succeed.
You please just list me the involved steps on the basis of your own blocking including...
1. splitting to O grid block from the initial block,
2. deleting some of the blocks & then,
3. association of block edges to curves of the geometry.... for the same blocking & geometry as you have posted above here.

Please correct my procedure if above seems to be wrong.
If possible please attach some images.
Thanks a ton for your response..i was really feeling helpless.

----------------------
regards
Pradeep
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Old   November 30, 2010, 01:45
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Post some pics of your blocking ... I followed the top-down approach exactly and it worked.
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Old   November 30, 2010, 02:00
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Old   November 30, 2010, 02:31
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this is the picture
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Old   November 30, 2010, 02:49
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this is the picture...of two kind of blocks ..that i think i can use..
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File Type: jpg BLOCKING.JPG (53.9 KB, 24 views)
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Old   November 30, 2010, 06:51
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I could not under stand..whether first delete the central block and then split in to O-grid block ..or first split the original block in to O-grid block & then delete the central block.
Also after splitting in to O-grid block association between edges and curves under Associate tab becomes very confusing.
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Old   November 30, 2010, 06:54
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First create O-grid then delete the central block
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Old   November 30, 2010, 07:00
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but after creating O-grid, the association between edges and curves under Associate tab becomes very confusing as there are many blocks and many edges now.
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Old   November 30, 2010, 07:16
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The main problem is of association (between block edges & geometry curves )or you may call it mapping, unless which one can not proceed further for generating mesh.
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Old   November 30, 2010, 07:54
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hello pradeep

can you post the image of the c topology which you made before association. since for this geometry there will be only 3 blocks after deleting one.
i will try to make a ppt and send you later seeing your topology.

Thank you
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Old   November 30, 2010, 12:51
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Hello jeevan..i have already posted two pics showing the same..!!

thnx forur response
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Old   November 30, 2010, 13:51
Default Not an Ogrid at all...
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pradeeppandeygbpec, your images show an HGRID split, not an OGRID at all.

You should start over...

1) Re initialize blocks to get one single block.

2) Ogrid, select the block, select the three faces as shown in my illustration.

3) Apply. You will now have a CGrid with 4 blocks. The three outer blocks are your Pipe, the inner block is not needed. Your index control should have 4 indices, i, j, k, and O3.

4) Delete the inner block.

5) Associate the remaining blocks to the pipe.

...
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Old   November 30, 2010, 13:52
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Alternatively, you can just take that single initial block and fit it to the pipe... (project the edges at one end to the curve and the inlet of the pipe, and then project the opposite edges to the curves at the outlet of the pipe. Then add splits for control points so you can steer the block along the pipe.
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