  We consider the dynamics of active nematics droplets on flat surfaces, based
on the continuum hydrodynamic theory. We investigate a wide range of dynamical
regimes as a function of the activity and droplet size on surfaces
characterized by strong anchoring and a range of equilibrium contact angles.
The activity was found to control a variety of dynamical regimes, including the
self-propulsion of droplets on surfaces, scission, active wetting and droplet
evaporation. Furthermore, we found that on a given surface (characterized by
the anchoring and the equilibrium contact angle) the dynamical regimes may be
controlled by the active capillary number of suspended droplets. We also found
that the active nematics concentration of the droplets varies with the
activity, affecting the wetting behaviour weakly but ultimately driving droplet
evaporation. Our analysis provides a global description of a wide range of
dynamical regimes reported for active nematics droplets and suggests a unified
description of droplets on surfaces. We discuss the key role of the finite size
of the droplet and comment on the suppression of these regimes in the infinite
size limit, where the active nematics is turbulent at any degree of activity.
