The Role of Impurities in Cavitation‐Threshold Determination

We have extended the theoretical work of Harvey et al. [J. Cellular Comp. Physiol. 24, 1–22 (1944)] and Strasberg [J. Acoust. Soc. Amer. 31, 163–176 (1959)] in order to consider the conditions that must exist in a liquid for a vapor cavity to be nucleated from an imperfectly wetted solid impurity (mote) in the liquid. It is found that, for sufficiently small and readily wetted motes, the tensile stress required for nucleation increases with increasing surface tension and decreasing mote size but is almost independent of the gas content and history of the liquid. On the other hand, for sufficiently large and imperfectly wetted motes, the gas content of the liquid and its history are crucial, whereas the mote size and the liquid‐vapor surface tension play no role in determining the conditions for nucleation. The qualitative predictions of this theory of moted‐induced nucleation bring some semblance of order to a wide variety of observations of statically induced cavitation and low‐frequency acoustic cavitation reported in the literature.