A molecular dynamic study on liquid droplet evaporation under low atmospheric pressure conditions

Abstract

Evaporation at high altitudes under low atmospheric pressure has garnered significant attention due to its distinct behavior compared to standard pressures. To address the effects of atmospheric pressure, molecular dynamics simulations are conducted on liquid droplets under three different conditions: 0.1 bar, 0.5 bar, and 1 bar. The temporal evolution of macroscopic parameters and the spatiotemporal dynamics of the liquid droplet are analyzed. The results show that reduced interactions, due to the low number density of nitrogen particles, lead to lower heat absorption by the liquid and a thinner liquid-gas interface, resulting in a lower evaporation rate at low atmospheric pressure. An increased initial evaporation rate at 0.1 bar is observed, resembling evaporation into a vacuum. The discrepancy between the D² law and the MD results increases as the vacuum degree rises, suggesting that the D² law is not suitable for predicting droplet evaporation behavior under low atmospheric pressure conditions. This work provides a fundamental reference for the design of evaporative cooling systems in high-altitude, low-atmospheric-pressure environments.