The rupture of a liquid layer by solutocapillary flow

摘要

The development of a strong deformation of the surface of a thin viscous liquid layer on a horizontal wettable substrate is experimentally studied. The deformation develops owing to a concentration-induced surface tension gradient that appears as a result of the deposition of a droplet of a soluble surface-active liquid onto the free surface of the layer. The conditions under which the viscous liquid layer is ruptured and the place beneath which the spreading droplet becomes partly uncovered are studied. For different pairs of liquids, the dependences of the radius of the dry spot on time, on the volume of a deposited droplet, on the horizontal sizes and thickness of the layer, and on the difference between the surface tensions of the droplet and the layer are obtained. It is shown that the rupture occurs at an appreciably larger initial thickness of the liquid layer than in the case of thermocapillarity. The critical thickness of the layer, at which its deformation reaches the substrate, is virtually independent of the amount of the deposited surfactant and is determined mainly by the surface tension gradient on the surface.