Film rupture in the diffuse interface model coupled to hydrodynamics - art. no. 031602

The process of dewetting of a thin liquid film is usually described using a long-wave approximation yielding a single evolution equation for the film thickness. This equation incorporates an additional pressure term-the disjo ining pressure-accounting for the molecular forces. Recently a disjoining p ressure was derived coupling hydrodynamics to the diffuse interface model [ L. M. Pismen and Y. Pomeau. Phys. Rev. E 62, 2480 (2000)]. Using the result ing evolution equation as a generic example for the evolution of unstable t hin films, we examine the thickness ranges for linear instability and metas tability for flat films, the families of stationary periodic and localized solutions. and their linear stability. The results are compared to simulati ons of the nonlinear time evolution. From this we conclude that. within the linearly unstable thickness range, there exists a well defined subrange wh ere finite perturbations are crucial for the time evolution and the resulti ng structures. In the remainder of the linearly unstable thickness range th e resulting structures are controlled by the fastest flat film mode assumed up to now for the entire linearly unstable thickness range. Finally, the i mplications for other forms of disjoining pressure in dewetting and for spi nodal decomposition are discussed.