Analysis of partial electrocoalescence by Level-Set and finite element methods

The coalescence of a water drop in a dieletric oil phase at a water layer interface in the presence of an electric field is simulated by solving the Navier-Stokes and charge conservation equations with the finite element method. The proprietary software Comsol Multiphysics is used for this purpose. The interface between the oil and water phases is tracked by implementing a Level Set approach. The sensitivity of the model with respect to some input parameters are reported. In particular, the calculations are sensitive to the size of the computational grid elements, interface thickness and re-initialisation parameter. The ratio between the volume of secondary droplets and the initial drop volume is calculated as a function of the initial drop size and compared with experiments available in the literature. A good quantitative agreement can be obtained if the parameters are suitably tuned. The model also predicts a strong role played by the water phase conductivity in the formation of progeny droplets.