404 
of state of water and the entronvy increments at the shock front demanded 
by the Hugoniot conditions show that up to pressures of 50,000 atmospheres 
the dissipated enthalpy Lov(p. sas amounts to only a few percent 
oe 
of thetotal enthalpy GW). We are therefore justified in approximating 
Ww by P 
= ayaa ee 
Ww = pS, ) (3.8) 
and in neglecting the dissipative term in Eqs. 3.7. With this simplifica- 
tion Eqs. 3.7 become 
an a ae 
Mont ct Dt 
(3.9) 
a4 _uxtru) = -7N. 
In this approximation the entropy transport equation becomes irrelevant. 
The initial conditions correspond to irrotational flow, and Eqs. 3.9 then 
demand that WX ue remain zero for all times. Moreover, for purely 
radial flow which we shall have to consider, Vx Wis zero under any con- 
ditions. We may therefore introduce a velocity potential My 3 
ee SS WHS (3.10) 
we 
Introduction of 3.10 into Eq. 3.9 yields 
ae: 1 Dw 
Wat te. 
BN. 
DY te) 
(3.11) 
Elimination of & between Eqs. 3.11 gives the wave equation 
18 
