Integration over portion of a surface

jtipton2 · July 15, 2010, 12:01

I would like to know if there is an easy way to calculate a function on a portion of a surface in CFX Post. For example, what would be the easiest way to integrate the wall shear stress in the fully developed region of a duct flow? So far, the only work around I can see is to run the simulation, observe the flow development length, modify the geometry to split the duct into two regions, and then rerun the simulation.

ghorrocks · July 15, 2010, 19:05

Use a contour line to define your fully developed region on the surface, make a user surface defined by the contour, do the integration on the user surface.

jtipton2 · July 16, 2010, 09:08

Thank you for the reply!

I let my axial dimension be the contour plot variable, made several user surfaces for each level of the contour in the fully developed region, and then combined them in a surface group. I'm assuming that's the easiest method.

ghorrocks · July 18, 2010, 06:18

If it works then it is all good.

mullenc525 · February 4, 2011, 17:43

Is there way to apply this method to volumes?

ghorrocks · February 5, 2011, 04:53

Apply what method?

If you mean calculate functions on sub-volumes, then yes. Define a volume as a sub-region of the full domain and calculate the CEL expression on the defined volume.

July 15, 2010, 12:01	Integration over portion of a surface	#1
jtipton2 New Member Joseph Tipton Join Date: Jun 2010 Posts: 27 Rep Power: 15	I would like to know if there is an easy way to calculate a function on a portion of a surface in CFX Post. For example, what would be the easiest way to integrate the wall shear stress in the fully developed region of a duct flow? So far, the only work around I can see is to run the simulation, observe the flow development length, modify the geometry to split the duct into two regions, and then rerun the simulation.

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July 15, 2010, 19:05		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	Use a contour line to define your fully developed region on the surface, make a user surface defined by the contour, do the integration on the user surface.

July 16, 2010, 09:08		#3
jtipton2 New Member Joseph Tipton Join Date: Jun 2010 Posts: 27 Rep Power: 15	Thank you for the reply! I let my axial dimension be the contour plot variable, made several user surfaces for each level of the contour in the fully developed region, and then combined them in a surface group. I'm assuming that's the easiest method.

July 18, 2010, 06:18		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	If it works then it is all good.

February 4, 2011, 17:43		#5
mullenc525 New Member Join Date: Dec 2010 Posts: 26 Rep Power: 15	Is there way to apply this method to volumes?

February 5, 2011, 04:53		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,692 Rep Power: 143	Apply what method? If you mean calculate functions on sub-volumes, then yes. Define a volume as a sub-region of the full domain and calculate the CEL expression on the defined volume.