Insights into numerical simulation of controlled ultrasonic waveforms driving single cavitation bubble activity

Abstract

A computational study treating cavitation phenomenon within a single bubble undergoing various controlled ultrasonic waveforms is presented in this paper. Numerical simulations using sinusoidal, square, triangular and sawtooth waves crossing an aqueous media, saturated with oxygen, are conducted upon various operational conditions of frequency and amplitude. Bubble radius, temperature and pressure were estimated over time for 64 combined cases. The obtained results show that at relatively low acoustic pressure, i.e. 1.5 and 2 atm, the square wave is proved to generate the highest temperature and pressure inside the bubble, while triangular and sawtooth ones remain the less interesting waveforms for sonochemical application within the same operational conditions. At higher amplitudes above 2.5 atm, this trend is changed, especially at low frequencies, i.e. 200 and 300 kHz, where square wave showed some limitations in attaining the optimal values of the strong collapse within one acoustic cycle.