Skewness of cells

apurv · March 1, 2012, 22:47

Hi All,

I have highly skewed cell in my geometry. On simulation in Fluent, I have to reduce the momentum urel down to 0.01 for a converged simulation with 1e-3 residual for continuity. I wanted to inquire if the velocity field in this case be considered accurate. I dont have any other results to validate.
Also, would decreasing the residual to 1e-4 help get better predictions.

Is there any way to know in Fluent or Workbench which cells are skewed?

Thanks for you time and I would really appreciate your help in this regard.

Apurv

scipy · March 3, 2012, 04:18

If you created your mesh in ANSYS Meshing you can use a metric there and just click on the bar in the metric graph to show your skewed cell. Other way would probably be to import your mesh into ICEM CFD, build a mesh topology, check the quality of all elements and do the same.. click on the histogram and it will show you the skewed elements.

You could also try to convert only the highly skewed cells into polyhedra inside Fluent, this would probably be the fastest solution to your problem. Inside Fluent you'd go to Mesh -> Polyhedra -> Convert skewed cells.. there you can set the goal skewness and let Fluent convert everything above that skewness (or below, there seems to be a difference when doing a Skewness metric in ANSYS Meshing, ICEM CFD and Fluent).

March 1, 2012, 22:47	Skewness of cells	#1
apurv New Member Apurv Join Date: May 2011 Posts: 10 Rep Power: 14	Hi All, I have highly skewed cell in my geometry. On simulation in Fluent, I have to reduce the momentum urel down to 0.01 for a converged simulation with 1e-3 residual for continuity. I wanted to inquire if the velocity field in this case be considered accurate. I dont have any other results to validate. Also, would decreasing the residual to 1e-4 help get better predictions. Is there any way to know in Fluent or Workbench which cells are skewed? Thanks for you time and I would really appreciate your help in this regard. Apurv

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March 3, 2012, 04:18		#2
scipy Senior Member Alex Pasic Join Date: Aug 2011 Location: Croatia Posts: 199 Rep Power: 15	If you created your mesh in ANSYS Meshing you can use a metric there and just click on the bar in the metric graph to show your skewed cell. Other way would probably be to import your mesh into ICEM CFD, build a mesh topology, check the quality of all elements and do the same.. click on the histogram and it will show you the skewed elements. You could also try to convert only the highly skewed cells into polyhedra inside Fluent, this would probably be the fastest solution to your problem. Inside Fluent you'd go to Mesh -> Polyhedra -> Convert skewed cells.. there you can set the goal skewness and let Fluent convert everything above that skewness (or below, there seems to be a difference when doing a Skewness metric in ANSYS Meshing, ICEM CFD and Fluent).