Theoretical and Numerical Comparisons of Evaporation Models for Liquid Droplets

Evaporation of liquid droplets is a phenomenon that has received considerable attention yet still presents fundamental modeling questions that remain unresolved. Among the most prominent of these questions concerns the similarities and differences between two principal evaporation models: diffusion-limited and one-sided. These models differ greatly in their formulation and ease of implementation but relatively few works to date have performed a side-by-side evaluation of their predictions. We use lubrication theory and numerical simulations to develop physical understanding by comparing and contrasting predictions of these two models. The time evolution of the droplet radius and contact angle are tracked, and the influence of thermal Marangoni forces on these is considered. Because droplets often contain suspended particles, we also investigate the case where the droplet contains colloidal particles and examine the predicted particle deposition patterns. Our results provide insight into the conditions under which the two evaporation models provide qualitatively different predictions as well as the physical mechanisms responsible for these differences.