BUBBLE EXCITATION OF SURFACE-WAVES AND AEROSOL DROPLET PRODUCTION - ASIMPLE DYNAMICAL MODEL

A novel theoretical analysis is presented of the dynamics of bubble-me diated jet droplet production. The aerosol particle is recognized in i ts ''bound state'' in a capillary surface wave which is generated by a bursting bubble. The spatial excitation profile-as known from photogr aphic data-is discussed by means of an argument involving a separation of time scales. By taking account of the dispersion relation for surf ace waves, the ensuing temporal behavior (of the local amplitude, vert ical velocity, acceleration, and radius of curvature) is calculated an alytically. The droplet is ejected just prior to the instant of maximu m local (vertical) deceleration. Energy balance considerations applied to the transition from its bound state to its ''free state'' allow th e prediction of the droplet size (as a function of bubble radius) and of the ejection velocity (as a function of droplet size). Numerical ca lculations support the analysis. The agreement with experimental data is shown to be good.