Coupled self-organization: Thermal interaction between two liquid films undergoing long-wavelength instabilities

TL;DR

This paper investigates how thermal interactions between two liquid films influence their stability, revealing new oscillatory instability modes that do not occur in isolated layers, through linear analysis and numerical simulations.

Contribution

It introduces a coupled model for two interacting liquid films and uncovers novel oscillatory instabilities caused by thermal coupling.

Findings

Thermal coupling alters stability properties significantly.

Oscillatory instabilities can emerge in coupled films.

Independent layer behavior is substantially different from coupled system.

Abstract

The effects of thermal coupling between two thin liquid layers, separated by a gas layer, are discussed. The liquid layers undergo long-wavelength instabilities driven by gravitational and thermocapillary stresses. To study the dynamics, both a linear stability analysis and a full numerical solution of the thin-film equations are performed. The results demonstrate that the stability properties of the combined system differ substantially from the case where both layers evolve independently from each other. Most prominently, oscillatory instabilities, not present in single-liquid layer configurations, may occur.