Rogue Nanowaves: A Route to Thin Film Rupture*

Understanding the stability of thin films and their potential to spontaneously rupture is crucial for a wide range of fluid-based applications.  Over the last thirty years, there has been significant progress in understanding the stability of ultra thin films, where disjoining pressure competes with surface tension to dictate whether or not a hole is formed in the so-called 'spinodal regime' of dewetting.  Mathematically, this corresponds to a long-wavelength linear instability and, notably, it is known that thermal capillary nanowaves, driven by Brownian motion in the bulk, play a key role in speeding up this instability, to bring theory in line with experiments.

Here, we consider an alternative and complementary possibility - that the formation of rogue nanowaves can lead to the rupture of linearly stable films.  Experimentally, such a 'thermal regime' has been observed, but a theoretical framework and predictive capability for this regime is absent.

In this talk, it will be shown that the film's dynamics can be described by a stochastic thin film equation, which naturally captures the generation of nanowaves and, once solved computationally, predicts the rupture of linearly stable nanofilms.  Then, using large deviation theory, which has recently been applied to model rogue ocean waves, we are able to formulate a theory which describes the most likely route to rupture and the timescale associated with this process, which compare well to our direct simulations.  Finally, comparisons to experimental analyses and molecular simulations will be presented and directions of future research discussed.