Inertial rupture of ultrathin liquid films

Abstract

Theory and numerical simulations of the Navier-Stokes equations are used to unravel the inertia-driven dewetting dynamics of an ultrathin film of Newtonian liquid deposited on a solid substrate. A classification of the film thinning regimes at finite Ohnersorge numbers is provided, unifying previous findings. We reveal that, for Ohnesorge numbers smaller than one, the final approach to the rupture singularity close to the molecular scales is controlled by a balance between liquid inertia and van der Waals forces leading to a self-similar asymptotic regime with $h_{\text{min}}\propto {\tau }^{2/5}$, where $h_{\text{min}}$ is the minimum film thickness and $\tau$ is the time remaining before rupture. The flow exhibits a three-region structure comprising an irrotational core delimited by a pair of boundary layers at the wall and at the free surface. A potential-flow description of the irrotational core is provided, which is asymptotically matched with the viscous layers, allowing us to present a complete parameter-free asymptotic description of inertia-driven film rupture.

10 pages, 3 figures, submitted to Journal of Fluid Mechanics