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-   -   grid checked failed warning (http://www.cfd-online.com/Forums/fluent/50683-grid-checked-failed-warning.html)

zubair February 25, 2009 15:47

grid checked failed warning
 
Hi every one i am doing my final year project and i have made grids on a cylinderacle body in gridgen. when i open the case file in fluent and check the grids warning appeares that grid checked failed . i have no non positive volume. i chesked that please help me as soon as possible i will be very thankfull to you.

Ralf Schmidt February 25, 2009 16:11

Re: grid checked failed warning
 
Hi!

do you have a 2D axissymmetrical volume?

If yes, it could be, that some grid points are just slightly below the x-axis (something like 10^-8) - that couses non positive volumes.

You might correct that by translating the grid that little amount in +y direction.

Best whises Ralf

zubair February 26, 2009 06:48

Re: grid checked failed warning
 
Thanks Ralf . i will check that


John Chawner February 28, 2009 12:37

Re: grid checked failed warning
 
Hi zubair,

Ralf's suggestion is a good one. If you're doing half the body with a symmetry plane there might be cells that are actually on the other side of the plane by mistake. In fact, there's a script on our Glyph Script Exchange specifically designed to check for and repair that scenario.

The other thing you might want to check is whether your grid is left-handed. The cells could all be perfectly fine from a geometric standpoint, but if the computational axes are left handed, the Jacobians might appear negative. You can easily verify this in Gridgen by using the Examine function on your blocks and look at the Jacobian.

If your mesh has a singular axis (aka a pole) where brick elements get compressed into a wedge, some versions of Fluent complain about these degenerate hexes. You should call our Technical Support Team at 800-4PTWISE or email them at support@pointwise.com.

Best regards.

zubair March 1, 2009 03:53

Re: grid checked failed warning *NM*
 

zubair March 1, 2009 03:55

Re: grid checked failed warning
 
thanks john



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