Acoustic cavitation bubbles bubble nuclei

Generation Spontaneous generation of gas bubbles within a homogeneous liquid is theoreticaUy impossible (Bikerman, Foams Theoiy and Industrial Applications, Reinhold, New York, 1953, p. 10). The appearance of a bubble requires a gas nucleus as avoid in the liquid. The nucleus may be in the form of a small bubble or of a solid carrying adsorbed gas, examples of the latter being dust particles, boiling chips, and a solid wall. A void can result from cavitation, mechan-ic ly or acoustically induced. Blander and Katz [AlChE J., 21, 833 (1975)] have thoroughly reviewed bubble nucleation in liquids. 

As we will see later, the Rayleigh-Plesset description closely matches the actual radial behavior of a bubble as long as the non-radial deformations are small (or of short duration). Since the behavior of a bubble depends on the applied acoustic pressure, Apfel estimated the threshold associated to transient cavitation. A part of this threshold is, of course, common to the Blake threshold (explosive growth of a cavitation nucleus. Fig. 14). 

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