Ultrasonically stimulated low-frequency oscillation and breakup of immiscible liquid drops: Photographs

Shape oscillation and fission of drops of an oil in water were studied photographically. Novel theoretical results are also presented concerning the resonance response of drops. The initial radii of the drops observed were typically between 1 and 2 mm. Two-lobed oscillations of moderate amplitude were driven by the temporally modulated radiation pressure of an ultrasonic wave. The tendencies for drops to elongate and break are discussed qualitatively. The oil is more compressible than water. Radiation stresses repel the oil from pressure nodes of the ultrasonic standing wave. The excitation of a transient deformation that appears to run around the drop’s surface is noted.