On the interaction between ultrasound waves and bubble clouds in mono- and dual-frequency sonoreactors.

Since the last decades, extensive work have been done on the numerical modeling of mono-frequency sonoreactors, we here consider the modeling of dual-frequency sonoreactors. We first present the basic features of the CAMUS code (CAvitating Medium under UltraSound), for mono-frequency excitation. Computation at low, medium and high frequency are presented. Extension of the numerical tool CAMUS is also presented: Caflisch equations are modified to take into account the dual-frequency excitation of the sound. We consider 28-56, 28-100 and 28-200 kHz sonoreactors. Fields of cavitation bubble emergence are quite different from the ones under mono-frequency. Study of spatio-temporal dynamics of cavitation bubbles in a 28-56 kHz sonoreactor is also considered. Taking into account the pressure field induced by the dual-frequency wave propagation, we compute the Bjerknes force applied on the cavitation bubble that is responsible for the bubble migration. A two phase flow approach allows to compute the bubble migration.