Electrically driven coalescence of charged conical droplet in non-uniform electric field

Abstract

The dynamic behaviors of charged droplet coalescence in electric field has drawn much attention over the past decades due to its complex underlying physics and potential industrial application. This work experimentally investigated asymmetric coalescence dynamics of conical droplets in non-uniform electric field. With the effect of electric field, the cone apexes of deformed droplets merged with each other to form a liquid bridge that initially expanded but then retracted back gradually. It was found that the bridge length increased fast at initial conical coalescence and shrank slowly at retraction stage in various conditions. In addition, the effect of electric charge distribution and transportation on liquid bridge evolution behaviors was analyzed. The characteristics of cone angle and contact distance during droplet conical coalescence and recoil processes were quantitatively discussed with consideration of different parameters. Besides, the phase diagram for determining droplet coalescence and recoil was illustrated based on contact distance and electric Bond number, where the critical transition boundary was figured out with a linear increasing trend.