Breakup of a droplet in a high-intensity sound field

Abstract

Atomization of a small droplet in an intense ultrasonic field is studied theoretically. Three main stages are described including the flattening of the droplet, the growth of small-scale disturbances at its edge, and the parametric growth of capillary waves on its surface. The small-scale instabilities are responsible for the formation of the micron-size fraction of atomized liquid while the parametric instabilities cause the breakup of the droplet into relatively large fragments that form the coarse fraction. The rates of instabilities are determined and their dependences upon sound level, frequency, and parameters of the droplet are discussed.