Brard 
where 
Fa Gaies (7.7). 
1 
m_ being the mass of E, and r(C) the vector orthogonal to the axis 
A of the helicoidal motion of the body with its origin on A and its 
end at the center C of the domain Dj. Fo is thus the centrifugal 
force exerted on the set E of fluid points, i.e. the centrifugal force 
acting on the fluid mass ''displaced"' by the body. 
Case as 
This case differs from case a, in that V (0) and (or) Q E 
may depend on time. 
a 
Q 
724).” “does ao lodges aopky te ean ey Unetae 
ay ger apply At 
eS 
dQ 
y E 
curl Ye = eer Se : (7-8), 
and - VE cannot be identified with +—Vpq . The equilibrium of the 
set E of fluid points therefore requires that the expressions for the 
absolute force per unit mass be different inside Dg and inside Dj. 
iF = V denotes the expression of that force inside D, , its 
expression inside Dj is F + F‘, and we must have 
ee Woe (UG: es ty i NE oes 
p d ae ; dt E ene 
ty ag av. ay 
I ! =2 = il ' = i I 
curl F'(M »t) ae curl— (M »t) curl +> (M »t) 
inside D, (7. 9), 
i 
Since 
V'(M',t) - V.(M', t) = - V © (M',t), 
h —> 
Sacre Fe gee ee Vw (M',t_) 
ot oO : 7 8 
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