Electrically induced deformations of water–air and water–oil interfaces in relation with electrocoalescence

In connection with the phenomenon of electrocoalescence of water droplets in oil, the electrically induced deformations of some water–oil interfaces are studied. Such problems involve the strong coupling of hydrodynamics and electrostatics as well as the accurate tracking/capturing of the evolving interfaces. The paper presents a Finite–Element Arbitrary Lagrangian–Eulerian (FE–ALE) approach in deforming meshes to investigate the time-dependent deformation of the interface between highly conductive water and an insulating immiscible fluid. The developed numerical scheme is first tested and then used to solve two 2D axisymmetric EHD problems. Computed results are compared with predictions from asymptotic developments and with experimental measurements.