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Old   April 26, 2004, 12:48
Default negative vol
  #1
roy
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Hi, After importing the mesh file into fluent when I check the grid it always gives me negative vol and grid check failed. I tried many elements in gambit to change the mesh file like quadralater/tetrahedral/triangular. But it always gives -ve vol. I would really appreciate your help.

thanks
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Old   April 26, 2004, 17:39
Default Re: negative vol
  #2
xfshi
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do mesh again
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Old   April 27, 2004, 05:09
Default Re: negative vol
  #3
zxaar
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i would like to share that happened a week ago, i am not sure how much this will be help to you.

we created a simple two D mesh (A STRUCTURED one), and did some analysis on it. well since the results were not matching well with the experimental values, we dicided to refine the mesh. at some point of time, it happened that after importing fluent gave us 'neg-volume' error.

the reason for that might be: after a perticular level of refinement, the mesh becomes so small that spatially difference in vertices do not go well with error tolerances of fluent (i am assuming vol is calculated by Gauss theorum ... sum( Xi * Ax) over all the surfaces of vol) . so after just coarsen a little bit the neg-vol error disappeared.

check if this is the case with your mesh.
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Old   April 27, 2004, 10:38
Default Re: negative vol
  #4
Bob
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It's funny. I recently had a mesh done in Gambit that produced negative volumes. I spent hours trying to resolve the issue. So I decided to go ahead and import into Fluent. When I did that and checked the mesh Fluent reported no negative volumes. I have no idea why that happened.
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