Marangoni convection in an evaporating sessile droplet depending on the substrate temperature.*

We investigate numerically quasi-steady internal flows in an axially symmetrical evaporating sessile droplet of capillary size. The hydrodynamics of an evaporating sessile drop and effects of the thermal conduction in the droplet and substrate have been taken into account jointly. The equations have been solved by finite element method using ANSYS Fluent. Temperature distributions and the corresponding vortex structures in evaporating sessile droplets are obtained. The phase diagrams containing information on the number and orientation of the vortices depending on the ratio of substrate to fluid thermal conductivities and the contact angle, are presented and analyzed for different values of parameters. Depending on the substrate temperature, we obtain both axisymmetric and asymmetric fluid flow patterns.