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Old   January 9, 2011, 09:08
Default Mesh orientation and negative volumes
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Nick
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Hi All,

I'm simulating a 3d airfoil in cfx using icem mesher. I have a problem in cfx solver, I either get negative volumes or floating point overflow errors. It's very frustrating as I've changed things around many times to no avail.
Could mesh orientation cause these errors? I mean if you have some right-handed and some left-handed elements would the solution fail?
Also how can I get rid of negative volume elements? Many thanks.
Nick
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Old   January 9, 2011, 20:42
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Glenn Horrocks
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If you do too much smoothing with ICEM you can get negative volume elements. Be very careful with your smoothing.
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Old   January 10, 2011, 02:49
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Thanks for the answer. I suppose I need to change my blocking scheme. Another error I get is with regard to symmetry boundaries. Although my planes are clearly defined. In ANSYS solver the solution is aborted with the following message:

The symmetry boundary condition requires that the boundary patch |
| mesh faces form a plane or axis. However, face set 4 in the |
| symmetry boundary patch| is not in a strict plane, which means that at least one of its |
| faces is not parallel to the others

I don't know what's going on. I've checked my boundary planes many times. Any ideas? Many thanks.
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Old   January 10, 2011, 17:34
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The error means you have elements of that face off the plane, so keep checking to find them.
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