Evaporation of non-circular droplets

Abstract

The dynamics of thin, non-circular droplets evaporating in the diffusion-limited regime are examined. The challenging non-rectilinear mixed-boundary problem this poses is solved using a novel asymptotic approach and an asymptotic expansion for the evaporative flux from the free surface of the droplet is found. While theoretically valid only for droplets that are close to circular, it is demonstrated that the methodology can successfully be applied to droplets with a wide variety of footprint shapes, including polygons and highly non-convex domains. While the applications of this are numerous, the analytically-tractable case of deposition of solute from large droplets is examined in detail, including a matched asymptotic analysis to resolve the pressure, streamlines and deposition up to second order.