Hot Spot Conditions during Multi-Bubble Cavitation

Abstract

Together with the chemical effects of ultrasound, light is often emitted [1–5]. Such sonoluminescence provides an extremely useful spectroscopic probe of the conditions created during cavitation bubble collapse. Acoustic cavitation is the origin of both sonochemistry and sonoluminescence. The collapse of bubbles caused by cavitation produces intense local heating and high pressures, with very short lifetimes. As we will demonstrate in this chapter, in clouds of cavitating bubbles, these hot spots have equivalent temperatures of roughly 5000 K, pressures of about 1000 atmospheres, and heating and cooling rates above 1010 K/s. In single bubble cavitation, conditions may be even more extreme [6–7]. Thus, cavitation can create extraordinary physical and chemical conditions in otherwise cold liquids.