10 



THE CALCULATION OF THE CAVITATION DRAG 



If the drag of the cavitating body is D, then 



Equation [17] may also be written 



After linearization, Equation [17a] becomes 



D=-2pU,\[^[u(t,y,)-u(t,y,)]^ 



df^^ [17b] 



But 



u(t,yf,) = u^^Q{t,y^) + u,_Q(t,y^), 



where Ug_^(t,yg) is the x component of that part of the disturbance velocity on the body 

 which is induced by the body source distribution, and u^_M,y ) is the x component of that 

 part of the disturbance velocity on the body which is induced by the cavity source distribution, 

 thus: 



Z) = -2p[/,J [u,_,{t,yo) + u,_^(t,yo)-u(f,y,)]^dt [17c] 



/-O dy 



It is easily shown that J ^o-o^^'^o' 37~ 

 so finally, remembering that u\t,y^) ^ 



The integral on the right hand side of Equation [17d] is easily determined from Equa- 

 tions [6] and [11], using Equations [31] and [34] of Appendix 1, Part A: 



