CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Pointwise & Gridgen (http://www.cfd-online.com/Forums/pointwise/)
-   -   Gridgen Problem (http://www.cfd-online.com/Forums/pointwise/70491-gridgen-problem.html)

bro6789 November 25, 2009 23:34

Gridgen Problem
 
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

jchawner November 28, 2009 12:25

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

Black September 22, 2013 06:18

Quote:

Originally Posted by bro6789 (Post 237746)
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.


All times are GMT -4. The time now is 17:42.