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Old   August 2, 2004, 04:56
Default non-positive volume
  #1
Wenbin Song
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Hi there,

I am using fluent to model a 2D airfoil flow, the mesh was generated using Gambit with a boundary layer.

I am getting a warning message when using grid check in fluent:

WARNING: non-positive volumes exist.

minimum volume(m3): -3.565426e-12 maximum volume(m3): 1.663969e-01 total volume (m3): 3.139505+02

Face area statistics: minimum face area (m2): 8.642673e-07 maximum face area (m2): 6.597350e-01

Why am I getting non-positive volume while the minimum face area is greater than zero?

Could anybody give me a clue?

Thanks Wenbin
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Old   August 2, 2004, 18:13
Default Re: non-positive volume
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Ryan Zarnitz
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Sometimes this happens with gambit. The solution is to use the examine mesh tool in gambit to identify the problem areas and re-mesh them. The most common situation for me when this comes up is when there is a very narrow space between two volumes. Sometimes you can fix it using an alternate meshing algorithm, and sometimes you have to find a different way to subdivide the domain.
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Old   August 9, 2004, 12:18
Default Re: non-positive volume
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sijal
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this is usually happen when two mesh lines are intersecting each other

check themesh quality and see the areas which are narrow and mesh quality is bad , u will oberseve the above said thing

regards
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