Instabilities of a liquid layer locally heated on its free surface

Abstract

We report experimental results concerning patterns in a model experiment built to study buoyant-thermocapillary-driven flows. The fluid is situated in a cooled cylindrical container and locally heated on its free surface. The resulting temperature gradient induces a basic flow which draws the surface fluid from the hot center toward the cold boundary. When the gradient is increased and depending on the height of liquid, the basic flow destabilizes into different stationary patterns. Above a second threshold, the patterns become time-dependent. These different instabilities are characterized and compared to recent theoretical results.