Behavior of oblately deformed droplets in an immiscible dielectric liquid under a steady and uniform electric field

The deformation and breakup of droplets in a steady and uniform electric field were experimentally investigated. Droplets of silicone oil suspended in more electric-conducting caster oil undergoes the three following modes of deformation when subjected to an electric field: oblate deformation with a symmetric axis oriented close to parallel with the electric field, oblate deformation with a symmetric axis oriented obliquely to the electric field, and an oscillatory oblate-prolate deformation synchronized with a sit-up motion. Each droplet during the oscillatory motion is simultaneously observed from two directions, and the flow in the droplet is visualized by a tracer particle method. The oscillatory motion is revealed to involve electrorotation of the droplet. The conditions under which each of the three deformation modes or droplet breakup occurs are identified. (c) 2006 American Institute of Physics.