Johnson and Hsieh 



It should be noted that p is now the pressure at point P(x,y) in the flow field, and 

 Rq is the initial bubble size at p^, which is the free stream pressure. Using 

 Eq. (2), the size of bubble can be calculated for the following physically possible 

 cases: 



I. Cp + cr^ > . 



(a) When Q^ > ^ p\ 



K' = Ro; 



H'^ 



where 



(b) When Q^ < — P\ 



27 



M^O 



8/W 



27 



(3a) 



R' = R. 2i/— cos 



(3b) 



where 



6 = y cos-' 



II. Cp + a^ < 0. When Q^ < ^P^ , 



R - Ro 2^- cos -3- 



where 



(3c) 



6' = cos- ' 



It is interesting to note that Q^ = 4p3 27 in Case II corresponds to the criti- 

 cal point for the instability of the gas nuclei; that is, cavitation inception occurs. 

 This critical point is given by 



166 



