Conical breakup of droplets in dielectric liquid medium

Abstract

The conical breakup behavior of droplets in immiscible dielectric liquids under non-uniform alternating current (AC) electric fields is experimentally investigated using high-speed photography. The optical-microscopic morphological characteristics of the dynamic behavioral process of charged droplets under different electric field conditions are precisely captured. Two distinct conical breakup configurations, called the trident vibration and lotus vibration modes, are proposed, and their detailed structural parameters are discussed. The extremely small stable conical meniscus (semi-angles range of 11°–18.6°) is found in the liquid–liquid system. The distribution of cone angles under various spatial conditions is determined. In addition, the multilevel asymptotic characteristics of conical fragmentation are found due to the variances in spatial and temporal scales. The diameters of the droplets produced under the cone-jet mode could be as small as a few micrometers. The differences between the droplet breakup mode of AC and DC electric fields are also discussed. Overall, several interesting features are reported for the axisymmetric multi-cone broken morphology when droplets undergo breakup.