An Experimental Investigation of the Break-up of a Liquid Drop Falling in a Miscible Fluid

Abstract

A liquid drop falling in a lighter miscible fluid either undergoes a cascade of fragmentations, each appearing as a dynamic instability, or it mixes by diffusion, depending on the value of a fragmentation number F. F is the ratio of the diffusion time to the time required for the fluid to convectively mix. We assign an accurate experimental value to the critical fragmentation number Fc, which appears to be universal. When the fragmentation occurs, the interfacial area increases via successive splittings which display striking symmetries. We present experimental evidence and a qualitative explanation of such a phenomenon.