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-   -   Help with Mesh motion preview (http://www.cfd-online.com/Forums/fluent/50337-help-mesh-motion-preview.html)

Mustafa Ayad January 20, 2009 16:37

Help with Mesh motion preview
 
Hi all i have this error when i do Mesh motion preview of the angular velosity of gears in ger pump any one can help me.

Done.

Updating mesh to time 1.00000e-04 (step = 00001)... This is Clockwise Gear

CG_Omega for clock_wise: 0, 0, -210

CG Position for clock_wise: 7.06373e-306, 1.77272e-295, -2.68156e+154

CG Orientation for clock_wise: 7.06373e-306, 1.77272e-295, -2.68156e+154

This is Anti Clockwise Gear

CG_Omega for antic1ock_wise:0, 0, 210

CG Position for antic1ock_wise:7.06373e-306, 1.77272e-295, -2.68156e+154

CG Orientation for antic10ck_wise:7.06373e-306, 1.77272e-295, -2.68156e+154

WARNING: non-positive volumes exist.

Dynamic Mesh Statistics: Minimum Volume =-1.56742e-004 Maximum Volume =6.50694e-004 Warning: negative cell volume detected! Error: Update dynamic mesh failed. Negative cell volume detected. Error Object: ()

zongtwi January 20, 2009 21:33

Re: Help with Mesh motion preview
 
Does this only occur when you want to preview your mesh motion? What about when you run the simulation, does the same error occurs?

Obviously, I don't really know how your case is, but non-positive volume usually exists because your moving domain is connected to the stationary domain. You need to explicitly disconnect the different zones inside GAMBIT.

Hope that helps.


Uday January 20, 2009 23:40

Re: Help with Mesh motion preview
 
Hi

If your are getting an error for negative volumes the mesh some where might be collapsing i.e. forming degenrated cells.

1)The C.G. defination might be wrong you can check the motion of your gears with zone motion prior to mesh motion preview which will give you the exact motion set by your definations.

2)And if all the above things are rght try to reduce the time step.

3)Let me knw r u running the case in 64 bit machine

Uday

regards


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