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 interest to optimize chemical procedures. Characterization of an open air 477 kHz ultrasound reactor shows that, because of the collapse of transient cavitation bubbles and pulsation of stable cavitation bubbles, chemical reactions are enhanced. Numerical modelling is undertaken to determine the spatio-temporal evolution of cavitation bubbles. The calculus of the emergence of cavitation bubbles due to the acoustic driving (by taking into account interactions between the sound field and bubbles' distribution) gives a cartography of bubbles' emergence within the reactor. Computation of their motion induced by the pressure gradients occurring in the reactor show that they migrate to the pressure nodes. Computed bubbles levitation sites gives a cartography of the chemical activity of ultrasound. Modelling of stable cavitation bubbles' motion induced by the motion of the liquid gives some insight on degassing phenomena.

[1]  Ulrich Kunz,et al.  Design, modeling and performance of a novel sonochemical reactor for heterogeneous reactions , 1996 .

[2]  Michael J. Miksis,et al.  Effective equations for wave propagation in bubbly liquids , 1985, Journal of Fluid Mechanics.

[3]  K. Suslick,et al.  The sonochemical hot spot , 1987 .

[4]  Anthony I. Eller,et al.  Force on a Bubble in a Standing Acoustic Wave , 1968 .

[5]  K. M. Swamy,et al.  Modeling of three-dimensional pressure fields in sonochemical reactors with an inhomogeneous density distribution of cavitation bubbles. Comparison of theoretical and experimental results. , 1999, Ultrasonics sonochemistry.

[6]  Dominique Legendre,et al.  The viscous drag force on a spherical bubble with a time-dependent radius , 1998 .

[7]  S Luther,et al.  Acoustic cavitation structures and simulations by a particle model. , 1999, Ultrasonics sonochemistry.

[8]  N. Gondrexon,et al.  Degassing effect and gas-liquid transfer in a high frequency sonochemical reactor , 1997 .

[9]  T. Leighton.  The Acoustic Bubble , 1994 .

[10]  R. Clift,et al.  Bubbles, Drops, and Particles , 1978 .

[11]  Frerich J. Keil,et al.  Modeling of three-dimensional linear pressure fields in sonochemical reactors with homogeneous and inhomogeneous density distributions of cavitation bubbles , 1998 .

[12]  L. van Wijngaarden,et al.  On the equations of motion for mixtures of liquid and gas bubbles , 1968, Journal of Fluid Mechanics.

[13]  Joseph B. Keller,et al.  Damping of Underwater Explosion Bubble Oscillations , 1956 .

[14]  Olivier Louisnard.  Contribution à l'étude de la propagation des ultrasons en milieu cavitant , 1998 .

[15]  Andrea Prosperetti,et al.  Linear pressure waves in bubbly liquids: Comparison between theory and experiments , 1989 .

[16]  K. M. Swamy,et al.  A comparative study on the modeling of sound pressure field distributions in a sonoreactor with experimental investigation , 1999 .

[17]  S. Sochard.  Modélisation de la cavitation acoustique et de l'activation de réactions homogènes , 1996 .

[18]  A. Henglein,et al.  Sonochemistry : historical developments and modern aspects , 1987 .

[19]  Lawrence A. Crum,et al.  The Motion of Bubbles in a Stationary Sound Field , 1969 .