CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > ANSYS Meshing & Geometry

[ICEM] O-grid Blocking

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 29, 2017, 01:46
Default O-grid Blocking
  #1
Member
 
beyonder
Join Date: May 2015
Posts: 67
Rep Power: 9
beyonder1 is on a distinguished road
Hi,
I have trouble understanding the difference between these two type of blocking.
Consider a case of a concentric cylinder.

After Initializing block, I create O-grid,
1. Using only Block.
2. Using block and two faces.

Why there is extra block created in case of (1) at inlet/outlet. Also, the meshing is different at inlet/outlet compared to just inside. What is the purpose of this type of meshing?
Attached Images
File Type: png Capture.PNG (36.6 KB, 116 views)
beyonder1 is offline   Reply With Quote

Old   May 29, 2017, 07:42
Default
  #2
New Member
 
D. N. Venturi
Join Date: Jan 2013
Location: Brazil
Posts: 25
Rep Power: 11
venturi is on a distinguished road
There is something wrong with your mesh, in both cases. I always use the second method, select the block and the inlet and outlet faces. What you should get is closer to the image attached.

Maybe is an association problem.

I am pretty sure the ICEM tutorial has an example for this.


venturi is offline   Reply With Quote

Old   May 29, 2017, 07:44
Default
  #3
New Member
 
D. N. Venturi
Join Date: Jan 2013
Location: Brazil
Posts: 25
Rep Power: 11
venturi is on a distinguished road
venturi is offline   Reply With Quote

Old   May 29, 2017, 09:28
Default
  #4
Member
 
beyonder
Join Date: May 2015
Posts: 67
Rep Power: 9
beyonder1 is on a distinguished road
Yes, I am also getting the same thing you have uploaded when I use the second method. But the question I have is:
- What is wrong with the First Method if there is something?
- If you haven't tried First method earlier, can you check if you are getting something different on faces.
- What is the purpose of selecting inlet/oulet faces in second method? I know I am getting results with it but theoretically speaking why should we do this?
beyonder1 is offline   Reply With Quote

Old   May 29, 2017, 09:42
Default
  #5
New Member
 
D. N. Venturi
Join Date: Jan 2013
Location: Brazil
Posts: 25
Rep Power: 11
venturi is on a distinguished road
You have to select the faces so that ICEM knows in which direction it should perform the o'grid.

For instance, try selecting two opposing wall faces, you'll see that the constructed o'grid will be different.

This is useful when you have a more complex geometry. Another example is when you have two connecting pipes, sometimes you can even define only one face for the o'grid. This way the o'grid will stop when it find another block.
venturi is offline   Reply With Quote

Old   May 30, 2017, 02:37
Default
  #6
Member
 
Jan Surwiło
Join Date: Feb 2017
Posts: 31
Rep Power: 7
johny0688 is on a distinguished road
When you use only block without pointing faces the o-grid is created around hole block as a "shell" form, so the mesh from case 1 is good. When pointing face you told on which faces the o-grid will be projecting. Try to create ogrid by block and only one face e.g. inlet. Cut your geometry by plane along pipe and you will see how it works.
johny0688 is offline   Reply With Quote

Old   May 30, 2017, 03:11
Default
  #7
Member
 
beyonder
Join Date: May 2015
Posts: 67
Rep Power: 9
beyonder1 is on a distinguished road
Quote:
Originally Posted by johny0688 View Post
When you use only block without pointing faces the o-grid is created around hole block as a "shell" form, so the mesh from case 1 is good.
I still don't understand why case 1(using only block as 'shell') is good. It doesn't create o-grid on face and mesh will be skewed there. I want to know in which type of geometry one should prefer 'block only case' over 'block with face case.'
beyonder1 is offline   Reply With Quote

Old   May 30, 2017, 03:35
Default
  #8
Member
 
Jan Surwiło
Join Date: Feb 2017
Posts: 31
Rep Power: 7
johny0688 is on a distinguished road
Quote:
Originally Posted by shubham2941 View Post
I still don't understand why case 1(using only block as 'shell') is good. It doesn't create o-grid on face and mesh will be skewed there.
Ok, we have misunderstanding When I said 'is good' I mean that when you do not point faces, only block, the mesh should look exactly like in your picture. I mean it is not ICEM error. Of course the mesh from case 1 is not good.


Quote:
I want to know in which type of geometry one should prefer 'block only case' over 'block with face case.
It is rather due to the flow, not geometry. The o-grid is usually attached to the wall to calculate boundary layer. You should analyse your case and decided where o-grid should be attached and where not.
johny0688 is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[Other] Some questions about unstructured grid. Yanci OpenFOAM Meshing & Mesh Conversion 1 November 28, 2014 10:47
[ICEM] Y blocking and O grid kmgraju ANSYS Meshing & Geometry 2 August 15, 2014 06:02
Grid Adaptation Suresh FLUENT 0 October 15, 2003 13:18
GRID TO GRID INTERPOLATION in FLUENT calogero FLUENT 3 June 4, 2003 08:32
Numerical methods for discontinuous grid interfaces? Hansong Hang Main CFD Forum 12 September 16, 1998 22:26


All times are GMT -4. The time now is 07:28.