Kinetic Monte Carlo and hydrodynamic modeling of droplet dynamics on surfaces, including evaporation and condensation

Abstract

We present a lattice-gas (generalized Ising) model for liquid droplets on solid surfaces. The time evolution in the model involves two processes: (1) single-particle moves which are determined by a kinetic Monte Carlo algorithm, which incorporate into the model particle diffusion over the surface and within the droplets and also evaporation and condensation, i.e., the exchange of particles between droplets and the surrounding vapor, and (2) larger-scale collective moves, modeling advective hydrodynamic fluid motion, determined by considering the dynamics predicted by a thin-film equation. The model enables us to relate how macroscopic quantities such as the contact angle and the surface tension depend on the microscopic interaction parameters between the particles and with the solid surface. We present results for droplets joining, spreading, sliding under gravity, dewetting, the effects of evaporation, the interplay of diffusive and advective dynamics, and how all this behavior depends on the temperature and other parameters.