Influence of substrate heating on the evaporation dynamics of pinned water droplets.
The dynamics of evaporating water droplets deposited on a heated substrate is investigated numerically. Droplets are pinned with a contact line radius of R = 1 mm. Evaporative mass flow and convection occurring inside the droplets are studied for different heating substrate sizes L S and heating temperatures T S. A simplified model neglecting hydrodynamics in air and evaporative cooling and assuming droplets to be spherical caps is simulated with a finite element method. A toruslike convective cell appears inside the droplets as evaporation takes place. For L S/ R > 1, the contact line is warmer than the apex of the droplets, and convection generates a downstream flow in the vicinity of the symmetry axis of the droplets. For L S/ R < 1, it is the apex that is warmer. Convection then generates an upstream flow. The overall evaporation time is described. It slows when L S/ R > 1.
Girard
Fabien
F
Aix-Marseille Université - Université Paul Cezanne, UMR-CNRS 6263 ISM2, Centre St. Jérôme, BP 451 Marseille 13397, Cedex 20, France.
Antoni
Mickaël
M