CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

Create coarser mesh for post-processing

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

Like Tree1Likes
  • 1 Post By gschaider

Reply
 
LinkBack Thread Tools Display Modes
Old   March 2, 2012, 18:52
Default Create coarser mesh for post-processing
  #1
Member
 
Florian
Join Date: Nov 2009
Posts: 59
Rep Power: 7
Horus is on a distinguished road
Hello!

My current mesh has about 23 M cells. It's fine for solving but somewhat too large for post-processing. Is there any possibility to coarsen an existing OpenFOAM mesh including results?

Thanks!
Horus is offline   Reply With Quote

Old   March 2, 2012, 19:51
Default
  #2
Super Moderator
 
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 8,301
Blog Entries: 34
Rep Power: 84
wyldckat is just really nicewyldckat is just really nicewyldckat is just really nicewyldckat is just really nice
Greetings Florian,

mapFields perhaps? http://www.openfoam.org/docs/user/ca...5-280002.1.6.3

Although I'm not sure that it can work from a high-res mesh to a coarse mesh, since it's usually done the other way around.

Best regards,
Bruno
wyldckat is offline   Reply With Quote

Old   March 3, 2012, 10:36
Default
  #3
Assistant Moderator
 
Bernhard Gschaider
Join Date: Mar 2009
Posts: 3,915
Rep Power: 40
gschaider will become famous soon enoughgschaider will become famous soon enough
Quote:
Originally Posted by wyldckat View Post
Greetings Florian,

mapFields perhaps? http://www.openfoam.org/docs/user/ca...5-280002.1.6.3

Although I'm not sure that it can work from a high-res mesh to a coarse mesh, since it's usually done the other way around.

Best regards,
Bruno
I think that shouldn't be the problem. What he is asking for is an autoUnrefineMesh-utility. To my knowledge there is no such thing. What I'd do is: write the patches as STL (one of the surface-utilities should do that). Then use snappyHexMesh to generate you a coarse mesh (doesn't have to be high quality too)
turbfoam likes this.
gschaider is online now   Reply With Quote

Old   March 5, 2012, 05:19
Default
  #4
Member
 
Florian
Join Date: Nov 2009
Posts: 59
Rep Power: 7
Horus is on a distinguished road
I think mapFields would be so way to go. I've created a coarser mesh by setting the base size in my mesher (Spider) to a higher value. Curiously the mesher then avoided creating some patches it should have and consistent mapFields failed.

Ok, I'll be investigating that issue whith the mesher, thanks so far!

(if anyone knows about that behavior with Spider I appreciate a reply of course)
Horus is offline   Reply With Quote

Old   March 5, 2012, 09:03
Default
  #5
Member
 
Andre Z
Join Date: Dec 2009
Posts: 32
Rep Power: 7
LVDH is on a distinguished road
Hi,
I frequently do this.

Here is my approach:

1. I copy the case and call it _CM at the end.
2. I modify the blockMeshDict so it encloses a smaller volume. I do not need the farfield for visualizations.
3. I modify the snappyhexMeshDict. Here I keep a high refinement on the surfaces. I lower all other refinement levels by 2 (eg from 7 to 5). I only keep one cell between levels and a switch off the surface layers. This gets me from about 70e6 to about 8e6 cells.
4. I map the fields from the original case to the _CM case.
Done!
LVDH is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Number of cells in mesh don't match with size of cellLevel colinB OpenFOAM Native Meshers: snappyHexMesh and Others 11 January 13, 2015 12:47
Converting Starccm+ mesh Ladnam OpenFOAM 0 September 14, 2011 06:30
Help ! Create surface for sliding mesh. YH Tan FLUENT 0 October 5, 2008 04:21
Gambit problems Althea FLUENT 21 February 6, 2001 08:05
unstructured vs. structured grids Frank Muldoon Main CFD Forum 1 January 5, 1999 11:09


All times are GMT -4. The time now is 13:21.