Nonlinear stability and rupture of ultrathin free films

Abstract

The nonlinear long-wave stability and lifetimes of thin free films subjected to the excess Lifshitz-van der Waals (LW) forces are studied based on numerical solutions, and a weakly nonlinear theory (WNT), which neglects mode interactions. The WNT works best for the fastest growing (dominant) disturbances of small initial amplitudes, and also for relatively thick films. For such cases, the nonlinear viscous effects (stabilizing) and inertia (destabilizing) are usually less significant than the LW force (destabilizing), surface tension force, and the unsteady effects (both stabilizing). For large initial amplitudes, linearly stable disturbances can engender strong subcritical instabilities and film rupture due to the greatly enhanced LW forces, inertia and mode interactions.