Electrorotation of a viscous droplet in a uniform direct current electric field

We study both analytically and numerically the experimentally observed nonaxisymmetric droplet deformation and orientation in a uniform DC electric field [1]. The theoretical model shows that above a threshold electric field a rotational flow is induced about the droplet. As a result, drop shape becomes a general ellipsoid with major axis obliquely oriented to the applied field direction. The theory is in excellent agreement with the experimental data for high viscosity drops [2]. Low viscosity drops undergo significant deformation during rotation, which is captured by numerical simulations using the boundary integral method. \\[4pt] [1] Salipante and Vlahovska, Physics of Fluids, 22:112110 (2010)\\[0pt] [2] He, Salipante, and Vlahovska, Physics of Fluids,25:032106 (2013)