10' 



I0 ; 



10' 



I0 4 I0 5 10 I0 2 



DISTANCE (CHARGE RADII) 



10- 



^Oom^- 



OO 



CONST 



r"\J log R 



KIRKWOOD, BETHE 1942 

 LANDAU 1942 



MEYER-KOENIG 1944 



TIME 



Figure 3. Comparison of the asymptotic pressure decay relation with experiments. The curve which 

 represents the equation noted is adjusted to a good fit with experimental points near the 10° psi 

 pressure level. Experimental data are due to ARONS, reference 7. 



a rigorous treatment of the Shockwave phenomena produced by a detonating charge 

 has not been made. It would require the use of an electronic computer.* 



Long Distance Propagation 



Since the Shockwave pressure decreases when it propagates through the water, 

 one might assume that there will be a point where the amplitude has decreased so far 

 that the wave has lost its high-amplitude character and can be treated as a low ampli- 

 tude acoustic wave. Several workers in this field [6] have stated independently and 

 almost at the same time that a shockwave never becomes exactly an acoustic wave. 

 The asymptotic relation is noted on Fig. 3. A spherical acoustic wave decreases 

 inversely proportional with distance, but a weak shockwave decreases somewhat more 

 rapidly due to the factor ylog R in the denominator. 



If we compare this asymptotic law with experimental evidence, Fig. 3, we find 



Such a calculation has been recently reported by BRODE. 



329 



