We use molecular dynamics (MD) simulations of a two-component Lennard-Jones (LJ) fluid to analyze the energy flux from an inert gas to the interface of an evaporating liquid droplet. Using this analysis we derive an analytical equation for the radius of the droplet, R(t), as a function of time, t. The formula is valid for evaporation of droplets of any material or size into the gas. We apply equation for R(t) to experimental results of evaporation of water micro-droplets into air and glycerol, diethylene glycol and triethylene glycol microdroplets into the nitrogen gas evaporating in time from seconds to tens of minutes. The experimental results together with computer simulations span 12 orders of magnitude of evaporation times and more than 3 orders of magnitude of droplets' radii. Read more Soft Matter, 2013, 9, 7766

The Hertz-Knudsen (HK) equation is commonly used to predict the evaporation flux. This equation states that the flux is proportional to the difference between the pressure in the system and the equilibrium pressure for the liquid/vapor coexistance. We apply the molecular dynamics (MD) simulations of one component Lennard-Jones (LJ) fluid to test the HK equation in a wide range of thermodynamic parameters covering more than one order of magnitude in the values of the flux. The flux determined in the simulations is 3.6 times larger than the one computed from the HK equation. However, the flux is constant over time while the pressures in the HK equation exhibit strong fluctuations during simulations. This observation suggests that the HK equation may not properly grasp the physical mechanism of evaporation. Read more Soft Matter, 2015, 28 7201-6.