Pattern Formation from Evaporating Non-Newtonian Liquid Droplets

Paul Takhistov, Food Science, Rutgers University, 65 Dudley Rd., New Brunswick, NJ 08901

The drying process of non-newtonian droplets with a pinned contact line has been studied experimentally and theoretically. The time evolution of the surface shape is modeled by taking into account of the solvent evaporation, the internal flow driven by surface tension, and the gelation of the fluid. It is shown that the final shape of the solidified film changes from dot-type to ring-type as the initial concentration of solute increases, or the evaporation rate decreases, but this is due to a rather intricate balance of the change of the solvent evaporation rate and the change of viscosity