Oscillation-assisted liquid breakup of micron-sized droplets

Liquid droplet radiators (LDRs) provide lightweight, high-safety thermal management for space applications, but conventional Rayleigh-jet systems produce high-velocity droplets that cause splashing and fluid loss. This study employs a dynamic mesh VOF method to simulate piezoelectric-actuated droplet generation, revealing how surface tension, channel angle, and excitation parameters control droplet morphology. Results demonstrate that droplet spacing increases with surface tension and excitation amplitude, while droplet diameter decreases with higher amplitude and frequency. Jet breakup length shortens with larger channel angles and increased excitation intensity. Force analysis identifies inertial promotion vs capillary suppression of jet growth, with the Weber number governing extension rate. Optimal performance occurs at 45°–60° channel angles, where droplet oscillation is minimized. Five flow regimes are classified dimensionlessly, and a frequency correlation based on Rayleigh theory establishes a design criterion for monodisperse droplet generation via Re–Oh scaling for the nozzle with diameter of 20 μm.