An efficient numerical prediction of the crust onset of a drying colloidal drop

Abstract An efficient numerical approach is proposed on the crust formation of an isothermal drying spherical colloidal droplet in a stagnant gas, where the heat and mass transfer were governed by the Stefan flow. A purely diffusive mechanism with a moving boundary was considered. The droplet shrinking induced an accumulation of particles, in the vicinity of the droplet interface, up to the onset of a crust formation known as the locking point. The latter was used as a control parameter of the numerical procedure global behaviour. The performances of the present numerical scheme compared to classical methods, showed a rapid convergence with a drastic reduction in the number of nodes, at least two-hundred fold less. Furthermore, the accuracy and speed of the proposed method allowed to carry out an extensive study with respect to the Peclet number, thus enabling to point out three drying regimes.