# Cd = Cs + Cf + Ci?

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 April 17, 2010, 13:56 Cd = Cs + Cf + Ci? #1 New Member   Join Date: Dec 2009 Posts: 25 Rep Power: 7 I'm confused, ive just been reading a technical SAE paper which states Cx = Cs + Ci + Cf where Cs = shape drag coefficent (Technical paper description, i assume it means pressure drag) Ci = induced drag coefficent Cf = skin friction coefficent I assume that Cx = Cd in the x direction Is this true? I think i have been told in the past that Cd = Cf+Cs (pressure and friction components). In Starccm+ you can split the recorded Cd coeficent into pressure and shear components, but there is no mention of induced drag.

 April 18, 2010, 00:05 #2 Member   L.Y LIN Join Date: Mar 2010 Posts: 47 Rep Power: 7 in my knowledge,cd=.and here Cx = Cs + Ci + Cf ,maybe we can explain it in this way:taking an example,a football is flying in the air with rotaion,and magnus effect is in this progress,it may be the Ci,and the Cs means the without rotation. above is just my guess.anybody can explain it .haha..

April 18, 2010, 07:09
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 Originally Posted by iilw1314 in my knowledge,cd=.and here Cx = Cs + Ci + Cf ,maybe we can explain it in this way:taking an example,a football is flying in the air with rotaion,and magnus effect is in this progress,it may be the Ci,and the Cs means the without rotation. above is just my guess.anybody can explain it .haha..
So basically are you saying that Cdx = Csx + Cfx with a zero degree angle of attack for a symetrical streamlined body (like NACA 0012).

I think that would make sense, im certain CFD software counts induced drag as a form of pressure drag (as esentially thats what it is).

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