Electrically enhanced coalescence-jumping of saline nanodroplets: Insights from molecular dynamics simulations

Abstract

The coalescence-induced jumping of saline nanodroplets under the influence of an oscillating electric field is investigated via molecular dynamics simulations. This study systematically explores how droplet size, ionic concentration, and substrate wettability affect the dynamics of droplet coalescence and detachment. Three droplet configurations—pure-pure, pure-saline, and saline-saline—are analyzed on substrates of varying hydrophobicity, both with and without the application of an external electric field. Results show that increased ion concentration delays coalescence and suppresses jumping due to the nanoscale interfacial effects which increase energy dissipation. Increasing the substrates hydrophobicity and applying oscillating electric fields improve energy conversion and momentum transfer in saline systems by promoting charge redistribution and reducing adhesion losses. Smaller droplets demonstrate greater sensitivity to electric fields, further amplifying their jumping response. These insights provide a molecular-level understanding of nanoscale droplet jumping, which may aid in optimizing electrostatic demulsification and condensation technologies. © 2025 Elsevier B.V.