CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Mesh Generation & Pre-Processing Software > Pointwise & Gridgen

Gridgen Problem

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 25, 2009, 22:34
Exclamation Gridgen Problem
  #1
New Member
 
anony
Join Date: Nov 2009
Posts: 5
Rep Power: 16
bro6789 is on a distinguished road
Hi everyone,

I've created an unstructured grid using Gridgen and tried running it in Fluent. However, Fluent gave me an error saying that there were non-positive volumes when I ran the grid check. Somehow the max. volume recorded during the grid check was also negative. I tried reordering the domain in Fluent but that didn't solve the problem. Any suggestions?

Thanks in advance
bro6789 is offline   Reply With Quote

Old   November 28, 2009, 11:25
Default
  #2
Senior Member
 
John Chawner
Join Date: Mar 2009
Location: Fort Worth, Texas, USA
Posts: 275
Rep Power: 18
jchawner is on a distinguished road
Hello bro,

The first thing I'd do is get back into Gridgen and verify using the Examine command that all the volumes are positive. (I assume your mesh is all tets and 3D.)

The most telling clue is that Fluent thinks the max. volume is negative. This indicates an issue of handedness (for a structured hex grid) or a directional issue if your grid is 2D and perhaps not in the correct orientation for Fluent which has its own rules that that sort of thing.

Another thing to check is whether the cells are sufficiently small that loss of precision during data transfer could mess up the grid. Gridgen is double precision but sometimes numbers get truncated when they're written to a file.

Failing all of the above, contact our Tech Support Team at support@pointwise.com and they can dig deeper into the matter.

Best Regards
__________________
John Chawner / jrc@pointwise.com / www.pointwise.com
Blog: http://blog.pointwise.com/
on Twitter: @jchawner
jchawner is offline   Reply With Quote

Old   September 22, 2013, 06:18
Post
  #3
New Member
 
Black Ghost
Join Date: Sep 2013
Location: Xi'an
Posts: 2
Rep Power: 0
Black is on a distinguished road
Quote:
Originally Posted by bro6789 View Post
Hi everyone,

I've created an unstructured grid using Gridgen and tried running it in Fluent. However, Fluent gave me an error saying that there were non-positive volumes when I ran the grid check. Somehow the max. volume recorded during the grid check was also negative. I tried reordering the domain in Fluent but that didn't solve the problem. Any suggestions?

Thanks in advance
hi, bro6789,

You can try the command 'mesh/repair-improve/repair' in Fluent command line. May help to you.
Black is offline   Reply With Quote

Reply

Tags
fluent, gridgen, non-positive volumes


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
Gridgen export problem with memory allocation? july Pointwise & Gridgen 5 July 21, 2008 20:29
Problem in Tutorial problem of fluent Phanindra FLUENT 5 April 17, 2007 09:57
CFX & Gridgen user. Please help Jane CFX 1 March 15, 2004 00:17
problem with using colocated code Jack Main CFD Forum 0 December 15, 2002 00:15
Is this problem well posed? Thomas P. Abraham Main CFD Forum 5 September 8, 1999 14:52


All times are GMT -4. The time now is 18:43.