Direct observation and theoretical study of cavitation bubbles in liquid mercury.

The direct observation of cavitation bubbles emerging in liquid mercury under the action of mechanical impacts and theoretical investigations on the experimental results have been made. Through a glass wall, the image of cavitation bubbles appearing near or in contact with the wall was captured by high-speed cameras. Discrepancies found between the bubbles' growth rates determined experimentally and given by a single-bubble theory have been discussed using a theoretical model of Rayleigh-Plesset type that takes into account bubble-bubble and bubble-wall interactions. A theoretical equation for the asymptotic growth rate in a multibubble case has been given and time dependence of the growth rate under a constant negative pressure has been clarified.