Brard 
Furthermore, as the pressure does not depend on the axes, we have, 
by the momentum theorem 
Se Hy (OE) = Hy, [pg (ME) = wy Om) ] AE - m0 
This quantity is null because of (4.4) and ¢« =+0. 
Consequently 
p, (M_) = p, (M,). (4. 6) 
Hence the pressure is continuous through the free vortex sheet. 
For the sake of simplicity, let us suppose that we deal with 
only one moving body. 
We also assume that we deal with one vortex sheet only. The 
vorticity generated by the body is thus concentrated inside that vortex 
sheet. 
The absolute velocity V in the domain D' really occupied 
by the fluid can be divided into three components: 
- the velocity V4 induced by the vortex distribution 
(Dis 1 2.0 ett (>, 4T ) which permits the fluid located 
between) ; and Sis to be at rest with respect to the hull; 
> 
- the velocity V, of some incident flow, 
- the velocity Ve due to the free vortex sheet shed by the 
body. 
According to Section III, we have 
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