Finite Element Simulations of Transient Droplet Deformation in an Electrical Field

Deformation of droplets in an externally imposed electrical field is a widely studied phenomenon, and is an important component of microfluidic operations involving electrical actuation of droplets. In this study, we explore a general numerical formulation for the deformation of droplets under an imposed electrical field. The solution is presented for two perfect dielectrics carring no free charge. The numerical solutions are first compared with an asymptotic analytic result for small deformations to assess the accuracy of the method. Following this, the dynamics of the deformation are presented to characterize the typical response times of droplets subjected to a step change in the electric field. The results provide the basis for modeling the dynamic response and control strategies for manipulating the droplets, and may provide considerable insight into microfluidic operations based on electrowetting.