Jets and Shock Waves from Cavitation 



Fig. D4 - Cavity during rebound 



20 cm below the free surface of the water, and the walls and bottom of the con- 

 tainer were at comparable distances away. The ambient pressure and the 

 vapour pressure of the water were respectively 82.5 and 14.5 mm Hg absolute. 

 Earlier frames from the film show that the cavity initially expanded to a radius 

 of 1.76 cm and then collapsed in the familiar manner, with enormous rapidity in 

 the final stages of contraction. Frame A was taken about 0.15 msec after the 

 instant when the collapse was arrested, and the others were taken later at suc- 

 cessive intervals of 0.125 msec (i.e., the framing rate was 8000 per second). 

 The mean radius of the cavity when recorded in frame D is estimated to have 

 been 0.55 cm. 



The feature to which attention is drawn is that whereas in frame A the 

 water surrounding the cavity appears transparent, in frame B it appears 

 speckled by a multitude of minute bubbles. These have grown to much greater 



159 



