detect separation and reattachment points in Fluent

ivanbuz · November 4, 2009, 18:22

I want to get the separation and reattachment points in time-averaged simulation results, and I am a little frustrated now.

I checked the text books and it says du/dy=0 or dp/dx=0. I searched the forums and there is not much information about how to detect them.

I try plotting "mean x-wall shear stress" in "unsteady wall statistics" of the airfoil, and it seems to me that the separation point is where shear stress=0 (from positive to negative), and the reattachment point is where shear stress=0 again (from negative to positive).

Can anyone show me the correct way to detect these points? Thanks in advance!!!

thanos · May 3, 2010, 22:36

Hi!

instead of plotting press ''write'' in your X-Y panel and save the file in a .xls format. This will create an excel file. Do it for the shear stress on x axis and then examine the points from your excel file. As you correctly assumed, laminar separation occurs when the shear stress change from positive to negative and reattachment when it changes from negative to positive.

Good luck!

m zahid · January 20, 2015, 15:10

hi , is it necessary to do the unsteady analysis for the reattachment length or can we measure this by steady analysis. ????

advance thanks

November 4, 2009, 18:22	detect separation and reattachment points in Fluent	#1
ivanbuz Member Ivan Join Date: May 2009 Posts: 85 Rep Power: 17	I want to get the separation and reattachment points in time-averaged simulation results, and I am a little frustrated now. I checked the text books and it says du/dy=0 or dp/dx=0. I searched the forums and there is not much information about how to detect them. I try plotting "mean x-wall shear stress" in "unsteady wall statistics" of the airfoil, and it seems to me that the separation point is where shear stress=0 (from positive to negative), and the reattachment point is where shear stress=0 again (from negative to positive). Can anyone show me the correct way to detect these points? Thanks in advance!!!

May 3, 2010, 22:36		#2
thanos Member thanos Join Date: Oct 2009 Posts: 30 Rep Power: 17	Hi! instead of plotting press ''write'' in your X-Y panel and save the file in a .xls format. This will create an excel file. Do it for the shear stress on x axis and then examine the points from your excel file. As you correctly assumed, laminar separation occurs when the shear stress change from positive to negative and reattachment when it changes from negative to positive. Good luck! AbdelFree02 likes this.

January 20, 2015, 15:10	hi reattachment length	#3
m zahid Member Qureshi M Z I Join Date: Sep 2013 Posts: 81 Rep Power: 13	hi , is it necessary to do the unsteady analysis for the reattachment length or can we measure this by steady analysis. ???? advance thanks