Experimental study of fluid-wall heat transfer induced by thermocapillary convection: influence of the Prandtl number

This article concerns heat transfer due to thermocapillary convection induced by an air bubble introduced under a heated wall into a silicone oil layer. An experimental study is carried out under normal gravity conditions with direct measurements by means of a heat fluxmeter. Effects of the bubble size and the temperature gradient are systematically investigated for two values of viscosity. The nature of the thermocapillary convection state (stationary or oscillatory) is determined by shadowgraphy. Two regimes of heat transfer are made evident. They depend on the Prandt1 number but are independent of the state of the flow.