Radiation-pressure-induced capillary waves

Abstract

Capillary waves are often observed on the surface of acoustically levitated drops, bubbles, and shells. The onset and parameter dependences of such waves on bubbles and shells have been investigated. Via video and light scattering it has been established that the mechanism for converting the acoustic energy into wave motion is the Faraday instability. Measurements of pattern formation, fluctuation, and transition will be presented, as well as investigations of temporal dynamics. In particular, the transition to spatiotemporal chaos and/or turbulence is investigated. The shell is the primary ‘‘laboratory’’ for turbulence, since, for certain wall thicknesses and levitation pressures, the entire surface becomes covered with apparently turbulent capillary waves, accompanied by a reduction of the gravity-induced pooling. The potential uses of this knowledge to produce more uniform coatings in certain applications will be discussed. [Work supported by NASA.]