Experimental characterization of buoyancy- and surface tension-driven convection during the drying of a polymer solution

Within the framework of convection induced by evaporation, an experimental study of the drying of a polymer solution has been performed. Several visualisations of convective pattern development are presented: top view with a video camera and an IR camera, as well as visualisation in a vertical section. The appearance and origin (buoyancy- and/or surface tension-driven instabilities) of the convective structures are analysed as a function of the initial thickness and viscosity. Different regimes are obtained when comparing the lifetime of the convective patterns to the thermal transient regime induced by evaporation and to the formation of a thin viscous skin at the surface.