Stability of Liquid Films

Macroscopic thin liquid films are entities that are important in biophysics, physics, and engineering, as well as in natural settings. They can be composed of common liquids such as water or oil, rheologically complex materials such as polymers solutions or melts, or complex mixtures of phases or components. When the films are subjected to the action of various mechanical, thermal, or structural factors, they display interesting dynamic phenomena such as wave propagation, wave steepening, and development of chaotic responses. Such films can display rupture phenomena creating holes, spreading of fronts, and the development of fingers. The present work examines, through the solution of a onesided evolution equation as an initial value problem with periodic boundary conditions, the various mechanisms that affect the stability of liquid films. The numerical program employed to solve the non-linear evolution equation is validated by comparing the results produced with previously published data. The wavenumber associated with various destabilizing mechanisms is extracted. The effect of pinned boundary conditions versus periodic boundary conditions will be discussed.© 2010 ASME