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-   -   [GAMBIT] HELP!I have a problem when starting the unsteady iteration (http://www.cfd-online.com/Forums/ansys-meshing/71904-help-i-have-problem-when-starting-unsteady-iteration.html)

usst139 January 19, 2010 09:53

HELP!I have a problem when starting the unsteady iteration
 
I have a problem when starting the unsteady iteration in Fluent,and it said——"warning:non-positive volumes exist.
Error:divergence detected in AMG solver :pressure correction
Error object:()

I guess something wrong with my original grid in Gambit?
hELP ME!THANK YOU!

-mAx- January 20, 2010 02:50

2d or 3d?
if you are working in 2d axi-symetric solver, check out that your domain is in +(xy) plane
if 3d, go back to gambit and examine mesh (icone bottom righ). Choose volume and set the min to 1 and the max to 0.
It will show you negative volume cells

usst139 January 21, 2010 02:30

thank you,-mAx-:)
My condition is in 3D,and i checked the mesh when importing the mesh from Gambit to Fluent,and didn't find negative volume then.
I agree with you that there is sth improper in my mesh,but I've no idea how to improve it,now I 'm trying to use the Boundary Layer or Sizefunction to make a better mesh^
And in your reply,I don't understand the sentence your said that"mesh (icone bottom righ). Choose volume and set the min to 1 and the max to 0. It will show you negative volume cells",would you please explain it more simply?
Thank you again:)

-mAx- January 21, 2010 05:04

http://www.ent.ohiou.edu/~juwt/HTMLS.../tg01.htm#1447
choose Volume type (instead of skewness), then set to lower level to -1 and the upper to 0
Then update

...
After importing your mesh in fluent, do a Checkmesh and pay attention to warning regarding negative volume


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