CFX meshing aspect ratio problems

akash_morar · November 12, 2010, 11:35

Trying to mesh a wind tunnel in the CFX mesher and am getting warnings of aspect ratios greater than 50. What are acceptable aspect ratios for the mesh and how would i make it smaller.

Thanks

ghorrocks · November 13, 2010, 05:35

This is discussed in the CFX documentation, I think under obtaining convergence.

dada1204 · November 13, 2010, 09:49

the acceptable range of mesh aspect ratio is below 100.

ghorrocks · November 13, 2010, 23:41

The actual number depends on the flow you are simulating and where the element is in the flow. 100:1 is OK for single phase in the boundary layer adjacent to a wall where the flow is aligned with the element, but even 2:1 is not good enough for accurate surface tension models. I find sweeping statements like this useless.

Really you need to do a sensitivity study on it for your application. But if you describe the application we might be able to give you some tips based on our experience.

November 12, 2010, 11:35	CFX meshing aspect ratio problems	#1
akash_morar New Member Akash Join Date: Nov 2010 Location: Southampton Posts: 3 Rep Power: 17	Trying to mesh a wind tunnel in the CFX mesher and am getting warnings of aspect ratios greater than 50. What are acceptable aspect ratios for the mesh and how would i make it smaller. Thanks

November 13, 2010, 09:49	mesh aspect ratio	#3
dada1204 New Member Join Date: Oct 2010 Posts: 18 Rep Power: 17	the acceptable range of mesh aspect ratio is below 100.

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November 13, 2010, 05:35		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 18,016 Rep Power: 146	This is discussed in the CFX documentation, I think under obtaining convergence.

November 13, 2010, 23:41		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 18,016 Rep Power: 146	The actual number depends on the flow you are simulating and where the element is in the flow. 100:1 is OK for single phase in the boundary layer adjacent to a wall where the flow is aligned with the element, but even 2:1 is not good enough for accurate surface tension models. I find sweeping statements like this useless. Really you need to do a sensitivity study on it for your application. But if you describe the application we might be able to give you some tips based on our experience.