26 



0, = r^ 



^-[lafc^im 



Also from Equation [10] 



Furthermore, 



- ]_ [2iH - 1) [H + 3) J \ r^ )j 



\ H (H + 1)^ ] I d cos a \ 

 [2 [H -!)(// + 3)J V r^ } 



h = H 



1 + 



r H^ (H + 1) ] 1 6 cos a \ 

 [(H-l) (W+ 3) J \ r I 



In the wake where r .. = 



2 



[87] 



[88] 



[89] 



TURBULENT WAKE 



The boundary layer leaving the tail of the body as the wake has a somewhat higher 

 pressure and larger momentum area fi^ than the wake far downstream. Since the momentum 

 area Q^ of the wake far downstream determines the drag of the body, a relation is required 

 between 12^ and the momentum area fl of the boundary layer at the tail. 



With no skin friction in the wake and with negligible effect from the normal-stress term 

 the momentum equation [61] reduces to 



iSL+ (A + 2) il ii^ = 

 dx U dx 



[90] 



Integrating by parts over the length of the wake from the tail to infinity downstream yields 



h 



fl 





[91] 



where the limiting value of h at infinity is unity 



3 U 



dh 



C "e U 



The evaluation of exp In -^ 



3r 



jl_ ^ / a-i V 



proceeds empirically. Experimental evidence 



suggests an empirical fit of a higher order parabola of form 



- 1 \9 



m^ 



[92] 



In -^ 



