Liquid interface tilt angle under thermal gradient: the surface-tension temperature coefficient

Abstract

Under an applied horizontal temperature gradient, the free surface of a thin liquid layer gets tilted by a small angle proportional to the surface-tension temperature coefficient. The authors show the effect to be particularly large at the interface between two liquids with comparable densities. From the corresponding interfacial slope, measured optically under different boundary conditions, one could draw an accurate determination of the upper liquid free-surface coefficient.