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-   -   [GAMBIT] mesh skewness (http://www.cfd-online.com/Forums/ansys-meshing/98129-mesh-skewness.html)

Musa March 4, 2012 00:21

mesh skewness
 
I am running a 2D gas-solid fluidized bed reactor simulation in fluent. The grid was created in gambit. my simulation breaks down after some time with the message divergence detected in AMG solver. I have searched many forums and people recommend that i check the quality of the mesh. Having done so the min and max skewness of my mesh is 1.305729e-10. can somebody advice me if this is good enough! what is the criteria for mesh skewness

-mAx- March 5, 2012 02:38

Quote:

Originally Posted by Musa (Post 347500)
Having done so the min and max skewness of my mesh is 1.305729e-10.

:rolleyes:
do it once again: in Gambit go in examine mesh and click on "worst element". And check the value of the skewness.
http://my.fit.edu/itresources/manual...equiangle_skew

Musa March 7, 2012 07:27

Thank you max! I checked it and it is 0.1306 i.e in the range between 0 and 2.5 meaning it is excellent but I can not still understand why i am getting the reverse flow problem. I have reduced my under relaxation factors as well!

-mAx- March 7, 2012 09:52

reverse flow may occures at the start of computation, but should disappear (no link with skewness).
else you may extend your outlet domain, it is closed to an obstacle

a_run_91 June 7, 2012 08:21

Hi...
I am a beginner in ANSYS FLUENT 13.0, so please excuse me to answer this simple question
" how to check the skew ness and other parameters(other than sizing,inflation,statitics etc which are visible when mesh is highlighted) of the mesh?

Thank you in advance...

everdimension June 7, 2012 09:32

In Ansys Meshing after you generate mesh in the Details choose 'Statistics' (click the + icon to unfold it). There you can see number of elements and nodes. And in the 'Mesh Metric' you can choose different kinds of mesh properties including Skewness and Orthogonal Quality.

In FLUENT when the mesh is loaded you can click 'Check' in the General tab and 'Report Quality' to check the orthogonal quality and aspect ratio properties.



Sizing and inflation options are also visible in the 'Details of Mesh' when you simply click 'Mesh' in the Outline tree in Ansys Meshing. If you have any locally applied inflation, then it appears under 'Mesh' in the outline tree, and after clicking desired inflation there you will also see its properties in the 'Details'.

a_run_91 June 7, 2012 10:56

Quote:

Originally Posted by everdimension (Post 365262)
In Ansys Meshing after you generate mesh in the Details choose 'Statistics' (click the + icon to unfold it). There you can see number of elements and nodes. And in the 'Mesh Metric' you can choose different kinds of mesh properties including Skewness and Orthogonal Quality.

In FLUENT when the mesh is loaded you can click 'Check' in the General tab and 'Report Quality' to check the orthogonal quality and aspect ratio properties.



Sizing and inflation options are also visible in the 'Details of Mesh' when you simply click 'Mesh' in the Outline tree in Ansys Meshing. If you have any locally applied inflation, then it appears under 'Mesh' in the outline tree, and after clicking desired inflation there you will also see its properties in the 'Details'.

Thanks everdimension for your detailed reply.....it helped me a lot.... :)

a_run_91 July 21, 2012 14:03

Quote:

Originally Posted by -mAx- (Post 347630)
:rolleyes:
do it once again: in Gambit go in examine mesh and click on "worst element". And check the value of the skewness.
http://my.fit.edu/itresources/manual...equiangle_skew


How do we remove these worst element??(ANSYS V14):confused:
I find some highly skewed cells near some simple surfaces(maximum skewness :0.999999)

suggestions will be helpfull..:rolleyes:
.
Thanks in advance:)


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