128 



THEORY OF THE SHOCK WAVE 



which was found to reduce the changes in G for a fixed value of 

 {t — r/{c -\- (t)), was obtained by taking G = r"12 with a equal to about 

 0.4 rather than 0.5. 



The peak pressure is computed by procedures equivalent to those of 

 Kirkwood and Bethe but differing in detail because of the changed sym- 



c 



O 



300 



REDUCED DISTANCE R/a^ 



Fig. 4.3 Calculated peak pressure at the side of a cylindrical TNT charge. 

 The dashed lines are for spherical charges and the dotted lines indicate transi- 

 tion to the dashed lines for charges of finite length. 



metry. The pressure decays much more slowly with distance, owing to 

 the fact that the energy of a given weight of explosive is concentrated 

 in a cylindrical slice rather than a spherical shell. The initial rate of 

 decay decreases as the shock front advances, and the rate of decrease 

 remains pronounced at larger distances from the charge than in the 

 spherical case. The decay of pressure at points behind the shock front 

 strictly should be computed separately for each point, but this compli- 



