| Summary: | Ultrasonic pretreatment has been widely used for biomass processing and sludge degradation. However, most of the researches made previously are confined to the acoustic cavitation irradiated by single transducer. When two transducers are introduced, interference of acoustic wave would transpire. Up to date, the effect of ultrasonic interference on cavitation is remained unknown. Therefore, the paper aims to develop a solver for preliminary investigation of the effect of superposition of acoustic wave on the performance of ultrasonic pretreatment. The simulation involves coupling between wave equation and Rayleigh-Plesset equation (RPE). Finite difference Euler explicit method is integrated with modified adaptive time marching method for computation of time-step sensitive RPE. Simulation results show a parabolic increment for relationship between frequency and enhancement of ultrasonic pretreatment for superposed irradiation, and the optimised frequency observed is at 900–1000 kHz.
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