Mojtaba Farrokhbin

Coalescence-induced droplet jumping plays a crucial role in heat transfer, dropwise condensation, and electrohydrodynamic systems. In this study, molecular dynamics simulations were performed to investigate the effects of pulsed and oscillatory electric fields on the coalescence and jumping behavior of saline nanodroplets. Two droplet configurations, namely symmetric saline-saline and asymmetric pure water-saline systems, were considered. The jumping height, droplet-substrate interaction energy, energy conversion efficiency, and dipole moment were analyzed to elucidate the underlying molecular mechanisms. The results show that, for the symmetric saline-saline system with 4 nm radius nanodroplets, the pulsed electric field outperforms the oscillatory field, increasing the jumping height and the surface-to-kinetic energy conversion efficiency by 8.8482% and 8.4306%, respectively. In contrast, for the asymmetric pure water-saline system, the oscillatory electric field enhances the jumping height and energy conversion efficiency by 3.7885% and 10.8498%, respectively, compared with the pulsed field. Dipole moment analysis reveals that the pulsed electric field promotes stronger alignment of water molecular dipoles in both systems; however, the enhanced dipole alignment does not necessarily translate into improved jumping performance. These findings demonstrate that, in addition to the electric-field waveform, ionic distribution and system symmetry play decisive roles in governing post-coalescence energy transfer pathways. This study provides new molecular-level insights into the controlled manipulation of droplet dynamics in electrohydrodynamic systems.