No abstract

International audienceThermo-capillary flow inside an evaporating water drop on heated or non-heated substrate is investigated. The modeling of the internal flow inside the drop takes into account the effects of the privileged evaporation near the contact line as well as thermo-capillarity. Heat transport equations by convection-diffusion in the drop, conduction in both solid and gas phases, and vapor diffusion in the surrounding air are solved numerically in a quasi-steady state. Results showed that the temperature profile at the drop surface rules the patterns of the thermo-capillary flow which is mainly dominant except near the contact line and toward the evaporation end. It is highlighted that the substrate temperature and its thermal conductivity have a great impact on the flow inside the drop. For instance, a multi-cellular pattern is induced within a heated drop for contact angles between 11 and 20. and the thermo-capillary flow could be reversed for contact angles less than 11. under certain conditions of the substrate thermal conductivity. Furthermore, the evaporation rate of the heated drop may be considerably influenced by thermo-capillarity at high contact angles