Interaction of surface-tension and buoyancy mechanisms in horizontalliquid layers

Horizontal liquid layers are prone to convective instability when subjected to appropriate vertical gradients of temperature and/or concentration. The two potentially destabilizing mechanisms leading to instability in the configuration, namely, surface tension and buoyancy, generally support each other, and their action can be tightly coupled. However, this finding, originally due to Nield, needs considerable qualification not only under the action of external forces such as Coriolis and Lorentz fields but also when the effects of wavy disturbances at the two-fluid interface are to be duly taken into account. Under different boundary conditions and in certain parameter ranges, significant departures from the coupling are demonstrated.