Numerical investigation of electrical coalescence between droplets and water layer in DC and AC electric fields

This study presents a detailed numerical investigation into the electrocoalescence phenomenon between individual water droplets and a horizontal water layer under the influence of both direct current (DC) and alternating current (AC) electric fields. The interaction is simulated using the Arbitrary Lagrangian-Eulerian (ALE) method, a robust computational technique that precisely resolves the sharp interface between two immiscible fluids. Several coalescence regimes are identified, including full merging (complete coalescence), the detachment of a secondary droplet (partial coalescence), and droplet elongation followed by breakup (stretching). These regimes are observed for both charged and uncharged droplets. Key factors such as electric field type, frequency of the applied field, and the presence of net charge on the droplet are systematically varied to determine their influence on the dynamic response and transition thresholds between different coalescence regimes. Insights derived from this research may support the optimization and design of electrostatic separation technologies, particularly electro coalescers used in petroleum processing.