Effect of droplet angle on droplet coalescence under high-frequency pulsed electric fields: Experiments and molecular dynamics simulations

Abstract

The droplet angle plays a key role in affecting electro-coalescence behavior of water droplets in oil. This work delves into the impact of the droplet angle on electrostatic coalescence in the high-frequency pulsed electric field by experiments and molecular dynamics simulations. Our findings revealed that a pulsed electric field promotes droplet coalescence before the droplets physically contact each other. Upon contact, notable oscillations ensue, with the electric field forces showing an adverse impact on the coalescence process. Depending on the degree of deformation, the droplet exhibits primary and secondary polarization states. Droplets exhibit a tendency to move apart when the initial droplet angle exceeds 75.93°, due to the same-charge repulsion and insufficient torque. An increase in the center distance ratio of droplets inhibits coalescence, resulting in a negative value in the decreasing rate of the droplet angle. These research findings offer valuable insights into improving the electrostatic demulsification process.