Numerical Modeling of Non-coalescence Outcomes for Different-sized Conducting Droplets Suspended in a Dielectric Liquid

The application of a strong electric field to water-in-oil emulsions is frequently used for phase separation owing to an electrical coalescence phenomenon. The present study is aimed to analyze numerically the probability of undesirable outcomes in the case when contacting droplets suspended in oil are of different sizes. Computations are based on the arbitrary Lagrangian-Eulerian (ALE) approach. The present study extends available data on non-coalescence outcomes that were obtained for equal-sized droplets and analyzes the scope of applicability of those simplified cases. It is shown that the threshold between complete and partial coalescence of different-sized droplets is nearly equal to that for equal-sized ones with the size of the bigger droplet from the former pair if the radius ratio is between 0.5 and 2. The partial coalescence yields many small droplets in the most cases and, in some cases, results in electrospraying inside the gap between two main droplets.