Brard 



The ihxx. of the vortex Tq = (1/S) n AVr,, inside the small area Sda^ normal 

 to Cp is equal to dy^ and is constant between two rings c^.c^ of abscissae cr^, 

 a; + da; on e„ (see Fig. 2). 



The rings C^Cm) are the curves y^(m) = constant. Moreover, on S^, 

 Vr dcr^ = djo • When 0= 0, v= , that is when we have a motion parallel to the 

 ( z,x) -plane with no angular velocity, it is convenient for what follows to write 



Definition of S^ , 5 , Se 



T =:J-n AK 

 J *• 









Definition of the botmd vortex 1^ [^s: const, along Cq 

 and of the density \ {m) of doublets norzoal to the hull 

 when : 



1*) there is no wake* 



2*) the angular velocity is null. 



Figure 2 



824 



