The values of V Q and B* can only be determined experimentally. It 

 is evident now why it is not necessary to determine the exact value of C L . 

 As long as C L is constant its effect will be reflected in the value of B*. 

 We may recall now that u is a periodic function of time which as the ex- 

 periments indicated can be approximated by the right hand side of equation 

 (3-24). Consequently f is a periodic function too which means that a more 

 appropriate form of equation (4-13) would be 



2 

 ,TT/2poo z_ 



„~ 2 



P =rr 



V2- 



dz duot 



(4-13a) 



* ^o 



The geometric representation of the probability p as expressed by 

 equation (4-13a) is shown in the sketch below. 



m ' 



It is evident from the form of equation (4-13a) that the turbulent field 

 was assumed constant during the entire cycle of the oscillatory mean flow. 



15 



