[ANSYS Meshing] Problem with O-grid in drill pipe

bahadir · April 10, 2011, 09:55

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, 21:26

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, 08:13

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 Pipe.jpg

PSYMN · April 12, 2011, 09:51

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, 06:48

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, 09:43

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, 15:51

hello
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, 06:00

Thanks German I will try

germangsilva · May 6, 2011, 12:51

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

April 10, 2011, 09:55	Problem with O-grid in drill pipe	#1
bahadir New Member Bahadir Join Date: Apr 2011 Posts: 5 Rep Power: 15	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?

April 11, 2011, 21:26		#2
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Your question doesn't have enough info for me to help you. And remember, a pictures is worth a thousand words... __________________ ----------------------------------------- Please help guide development at ANSYS by filling in these surveys Public ANSYS ICEM CFD Users Survey This second one is more general (Gambit, TGrid and ANSYS Meshing users welcome)... CFD Online Users Survey

April 12, 2011, 08:13	Pipe	#3
bahadir New Member Bahadir Join Date: Apr 2011 Posts: 5 Rep Power: 15	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 Pipe.jpg

April 12, 2011, 09:51		#4
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	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. __________________ ----------------------------------------- Please help guide development at ANSYS by filling in these surveys Public ANSYS ICEM CFD Users Survey This second one is more general (Gambit, TGrid and ANSYS Meshing users welcome)... CFD Online Users Survey

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April 13, 2011, 06:48		#5
bahadir New Member Bahadir Join Date: Apr 2011 Posts: 5 Rep Power: 15	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.

April 13, 2011, 09:43		#6
BrolY Senior Member AB Join Date: Sep 2009 Location: France Posts: 323 Rep Power: 22	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

May 5, 2011, 06:00		#8
bahadir New Member Bahadir Join Date: Apr 2011 Posts: 5 Rep Power: 15	Thanks German I will try

May 6, 2011, 12:51		#9
germangsilva New Member Germán González Silva Join Date: Mar 2010 Location: Campinas-SP Posts: 20 Rep Power: 16	I recommend upload geometry files, blocks to try to help more.