Liquid film rupture beyond the thin-film equation: a multi-component lattice Boltzmann study

Abstract

Under the condition of partial surface wettability, thin liquid films can be destabilized by small perturbations and rupture into droplets. The thin film equation (TFE) is one of the most popular theoretical approaches to describe this mechanism, but it is limited in principle to small equilibrium contact angles and ratios = h/L of film height h and lateral size L. Here, we use a multicomponent lattice Boltzmann (LB) approach to investigate systematically the stability of thin films in contact with a flat surface for large equilibrium contact angles and finite heights. The dispersion law predicted by the TFE turns out to be in very good agreement for angles as large as 130 • . The requirement of a small height is instead a more strict condition for the validity of the TFE, and agreement with LB results is found only for ×10 −3 . The presence of two fluid components allows for a much richer phenomenology than in the single component case, which reflects into the possibility of tuning the dewetting dynamics over a wide range of time scales.