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bahadir April 10, 2011 08:55

Problem with O-grid in drill pipe
Hi guys,

I'm new in the forum and leraning CFD recently for my graduation project, so any advice would be very much appreciated.

I created a drill pipe for the fluid path to be stimulated by using O-grid. However when I have a look at angles of grids from quality controls they are not so good. May be I am doing wrong with O grid ? Do some one help me?

PSYMN April 11, 2011 20:26

Your question doesn't have enough info for me to help you.

And remember, a pictures is worth a thousand words...

bahadir April 12, 2011 07:13

1 Attachment(s)
Helo Simon.
First of all thank you for trying to help me. My aim to make better the angle distribution in the quality control the range og my angles is 45-88 degrees. Here I attached my pichture i Hope it will help you Attachment 7226

PSYMN April 12, 2011 08:51

Your angles look fine. Most solvers are happy if you can get it above 9 or 18 degrees. What is your worst angle? What is your worst aspect ratio?

However, you distributions could use some work.

Your radial edges need more nodes and they should be bunched toward the walls to better capture the boundary profile.

Alternatively, you could rescale your ogrid (rather than add more nodes). But you would still want to bunch toward the wall (growth rate of 1.2 or 1.5 away from the wall is common)

Ideally you would have a smooth transition across your model.

You could try running the Orthogonal hexahedral smoother if you wanted.

bahadir April 13, 2011 05:48

First of all thank you very much for helping
My smallest angle is 45 deg. so based on your reply it seems that OK.
I will try to change as you said , hope will work.:)

BrolY April 13, 2011 08:43

For your information, with the solver I'm using, if the smallest angle is superior to 18, it's good.
So with 45, you are more than good ;)

germangsilva May 4, 2011 14:51

1 Attachment(s)
another way to improve the quality and appearance of the mesh is to reduce the size of Ogrid.

Blocking> Edit Block> Modify Ogrid

in Modify Ogrid> Method = Rescale Ogrid + Edge (is the radial O-grid selected edge) + Offset = 0.7

bahadir May 5, 2011 05:00

Thanks German I will try :)

germangsilva May 6, 2011 11:51

I recommend upload geometry files, blocks to try to help more.

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