THE SEQUENCE OF EVENTS 



11 



motion which does not scale in the same way as the effects of internal 

 forces and boundaries, the principle of similarity for shock waves de- 

 scribed in section 1.3 does not hold for bubble motion in the general 

 One can derive scaling factors which express the theoretical 



case. 



equations in an approximate form and account for the major features of 



1770 LB /IN' 



80 LB/IN^ — 



I 

 SEC 



TIME 



0.69 sec 



Fig. 1.5 Pressure 60 feet from a 300 pound TNT charge fired 50 feet below 



the surface. 



bubble motion. The scaling laws and feasible numerical calculations 

 of bubble effects are, however, only approximate, and experimental 

 results are often not in very good agreement with tractable theoretical 

 calculations. 



1.6. Surface and Other Effects 



The preceding sections have outUned the more important properties 

 of underwater explosions as they would appear to sufficiently rugged 

 observers below the surface equipped with a sense for pressure measure- 



80 lb/in2 



MSEC 



MSEC 50 



MSEC 50 



(a) 25 FEET 



(b) 50 FEET 



(c) 80 FEET 



Fig. 1.6 Bubble pulse pressures 60 feet from 300 pound TNT charges fired 

 at 3 depths in 100 feet of water. 



