Explosion-Generated Water Waves 



Again, It should be emphasized that the objective is to obtain 

 an input condition for wave generation rather than to solve the many- 

 associated problems of bubble dynamics, shock propagation, and 

 radioactive debris distribution. However, these problems cannot be 

 ignored, inasmuch as they affect the wave generation process. 

 Extensive work has been performed on bubble dynamics of both con- 

 ventional and nuclear explosives (Snay [ 1966]). The energy partition- 

 ing between radioactive potential energy, thermal energy to heated 

 and vaporized water, shock energy, and kinetic and potential bubble 

 energy has been investigated by a number of authors (see, for ex- 

 ample, DASIAC Special Report 104 - Secret). Detailed studies of 

 shock propagation and pressure fields have been performed by many 

 investigators. Some of these studies neglect the effect of gravity; 

 others make gross assumptions about the thermodynamic properties 

 of the bubble. But all of these effects should be included in an 

 effective model for analyzing the wave generation process, unless 

 it can be shown that they can be neglected because they do not affect 

 the wave characteristics. 



2, 2 The Incompressible Phase 



The input condition being defined by the compressible phase, 

 the subsequent cavity behavior may be treated as incompressible 

 flow. It is tentatively proposed to analyze the wave generation pro- 

 cess through a numerical solution to the time-dependent, viscous, 

 incompressible flow of a fluid with a free surface. Figure 3 is an 

 experimental exajuple of near-burst free surface history. The most 



CENTERLINE 



FRAME 10 10 15 15 25 25 



64 FRAMES /s«c 

 WATER DEPTH - 8 ft. 

 DEPTH OF BURST -6 in. 



Fig. 3 Cavitv shape versus time - shot 11 (Courtesy of URS) 



75 



