# forceCoeffs lRef and Aref ??

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 March 18, 2016, 07:16 forceCoeffs lRef and Aref ?? #1 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 08:53.

 March 18, 2016, 08:18 #2 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, 04:40 #3 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?

July 9, 2024, 12:20
#4
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Shishir Gautam
Join Date: Dec 2020
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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.
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