Stability of an evaporating thin liquid film

We use a newly developed set of boundary conditions to revisit the problem of an evaporating thin liquid film. In particular, instead of the conventional Hertz–Knudsen– Langmuir equation for the evaporation mass flux we impose a more general equation expressing the balance of configurational momentum. This balance, which supplements the conventional conditions enforcing the balances of mass, momentum, and energy on the film surface, arises from a consideration of configurational forces within a thermodynamical framework. We study the influence of newly introduced terms such as the effective pressure, encompassing disjoining and capillary components, on the evolution of the liquid film. We demonstrate that this quantity affects a time-dependent base state of the evaporating film and is an important factor in applications involving liquid films with thicknesses of one or two monolayers. These factors lead to a revised understanding of the stability of an evaporating film. Dimensional considerations indicate that the most significant influence of these effects occurs for molten metals.