Numerical simulation of cavitation bubble dynamics induced by ultrasound waves in a high frequency reactor

The use of high frequency ultrasound in chemical systems is of major intere st to optimize chemical procedures. Characterization of an open air 477 kHz ultrasound reactor shows that, because of the collapse of transient cavita tion bubbles and pulsation of stable cavitation bubbles, chemical reactions are enhanced. Numerical modelling is undertaken to determine the spatio-te mporal evolution of cavitation bubbles. The calculus of the emergence of ca vitation bubbles due to the acoustic driving (by taking into account intera ctions between the sound field and bubbles' distribution) gives a cartograp hy of bubbles' emergence within the reactor. Computation of their motion in duced by the pressure gradients occurring in the reactor show that they mig rate to the pressure nodes. Computed bubbles levitation sites gives a carto graphy of the chemical activity of ultrasound. Modelling of stable cavitati on bubbles' motion induced by the motion of the liquid gives some insight o n degassing phenomena. (C) 2000 Elsevier Science B.V. All rights reserved.