  We investigate numerically quasi-steady internal flows in an axially
symmetrical evaporating sessile droplet depending on the ratio of substrate to
fluid thermal conductivities, fluid volatility, contact angle and droplet size.
Temperature distributions and vortex structures are obtained for droplets of
1-hexanol, 1-butanol and ethanol. To this purpose, the hydrodynamics of an
evaporating sessile drop, effects of the thermal conduction in the droplet and
substrate and diffusion of vapor in air have been jointly taken into account.
The equations have been solved by finite element method using ANSYS Fluent. The
phase diagrams demonstrating the number and orientation of the vortices as
functions of the contact angle and the ratio of substrate to fluid thermal
conductivities, are obtained and analyzed for various values of parameters. In
particular, influence of gravity on the droplet shape and the effect of droplet
size have been considered. We have found that the phase diagrams of highly
volatile droplets do not contain a subregion corresponding to a reversed single
vortex, and their single-vortex subregion becomes more complex. The phase
diagrams for droplets of larger size do not contian subregions corresponding to
a regular single vortex and to three vortices. We demonstrate how the
single-vortex subregion disappears with a gradual increase of the droplet size.
