Sonochemical cavitation phenomena in small bubbles

A theoretical study has been made on collapsing cavities in liquids. When a chemical reaction is not occurring in the cavity, the departure from the Rayleigh collapse time increases with decreasing Weber number. When a chemical reaction is taking place within the cavity, the conversion first decreases and then increases with decreasing initial radius of the cavity owing to the interaction of collapse time and gas temperature within the cavity. For large cavities the viscous damping effects are almost negligible, while for small cavities the damping of the cavity motion is quite significant. When an exothermic reaction is taking place within the cavity, the velocity of the cavity wall and maximum radius achieved upon rebound increase with each successive rebound until chemical equilibrium is approached. The influence of an increase in the number of molecules formed during the reaction upon collapse is described in the text along with a discussion of how various parameter and dimensionless groups affect the collapse of the cavity.