High-fidelity three-dimensional smoothed particle hydrodynamics simulations of evaporating liquid droplets in zero-gravity under transient and uniform heating

The evaporation of liquid droplets under transient heating is a critical process in numerous industrial and aerospace technologies, yet high-fidelity three-dimensional (3D) simulations capturing the transition between boiling regimes remain scarce. This paper addresses this gap by presenting a high-fidelity 3D Smoothed Particle Hydrodynamics study of van der Waals liquid droplets in zero-gravity subjected to uniform, transient heating. The core novelty of this work is the integration of a previously overlooked non-classical energy flux term within a 3D Lagrangian framework. This term, associated with the capillarity coefficient, is essential for accurately capturing the thermal dynamics and latent heat transport at the diffuse liquid–vapor interface. Our results reveal that under transient heating, the droplet evolution is characterized by two distinct kinetic stages: a nucleate-like boiling regime for short heating durations and a film-boiling-like regime as heating increases. We establish a novel predictive model demonstrating a nonlinear relationship between the equimolar droplet radius and heating duration, evidenced by a shift in sensitivity as the system transitions from nucleate to film boiling. Validated by a systematic 3D convergence study reaching 512 000 particles, these findings provide high-resolution benchmarks for vapor envelope evolution and transition thresholds in microgravity environments.