  In the outer envelope of the Sun and in other stars, differential rotation
and meridional circulation are maintained via the redistribution of momentum
and energy by convective motions. In order to properly capture such processes
in a numerical model, the correct spherical geometry is essential. In this
paper I review recent insights into the maintenance of mean flows in the solar
interior obtained from high-resolution simulations of solar convection in
rotating spherical shells. The Coriolis force induces a Reynolds stress which
transports angular momentum equatorward and also yields latitudinal variations
in the convective heat flux. Meridional circulations induced by baroclinicity
and rotational shear further redistribute angular momentum and alter the mean
stratification. This gives rise to a complex nonlinear interplay between
turbulent convection, differential rotation, meridional circulation, and the
mean specific entropy profile. I will describe how this drama plays out in our
simulations as well as in solar and stellar convection zones.
