Long interfacial waves in multilayer thin films and coupled Kuramoto–Sivashinsky equations

Abstract

The coupled Kuramoto–Sivashinsky (CKS) equations for multilayer downflowing films are derived and explored. The CKS equations exhibit a wealth of dynamical behaviour, displaying travelling periodic waves, regular and chaotic-like patterns, coexistence of different attractors, and perfect and imperfect synchronization of the interfaces. New physical effects are found, such as suppression of the Rayleigh–Taylor instability for heavy-top stratified films, and new surface-tension-driven instability.