forceCoeffs lRef and Aref ??

giammy92 · March 18, 2016, 08:16

Hi guys, what is the value to put in lRref and Aref when i define forceCoeffs? From OF' s libraries I've see that lRef is referred to lenght scale for moment but I don't understand on what I have to base. And for Aref

?
P.S. I have an airfoil with a chord of 0.5459 m

giammy92 · March 18, 2016, 09:18

and other question...the direction of drag is the opposite of flux, right? If this is true, for the tutorial airfoil2D because I have an angle of attack of 8° positive and then the y component of U is positive, the dragdir for me is (-cos8 -sin8 0). Is it right?

mqsim · March 23, 2016, 05:40

http://www.cfd-online.com/Forums/ope...lref-aref.html

Have you seen this thread?

shishirgautam · July 9, 2024, 13:20

Quote:

Originally Posted by giammy92

and other question...the direction of drag is the opposite of flux, right? If this is true, for the tutorial airfoil2D because I have an angle of attack of 8° positive and then the y component of U is positive, the dragdir for me is (-cos8 -sin8 0). Is it right?

Refer to the following illustration for direction vectors.

Best,
Shishir G.

March 18, 2016, 08:16	forceCoeffs lRef and Aref ??	#1
giammy92 Senior Member Join Date: Mar 2016 Posts: 133 Rep Power: 10	Hi guys, what is the value to put in lRref and Aref when i define forceCoeffs? From OF' s libraries I've see that lRef is referred to lenght scale for moment but I don't understand on what I have to base. And for Aref ? P.S. I have an airfoil with a chord of 0.5459 m Last edited by giammy92; March 18, 2016 at 09:53.

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March 18, 2016, 09:18		#2
giammy92 Senior Member Join Date: Mar 2016 Posts: 133 Rep Power: 10	and other question...the direction of drag is the opposite of flux, right? If this is true, for the tutorial airfoil2D because I have an angle of attack of 8° positive and then the y component of U is positive, the dragdir for me is (-cos8 -sin8 0). Is it right?

March 23, 2016, 05:40		#3
mqsim New Member Join Date: Feb 2016 Posts: 28 Rep Power: 10	http://www.cfd-online.com/Forums/ope...lref-aref.html Have you seen this thread?