  The goal of this paper is to study the large-time behaviour of a buoyancy
driven fluid without thermal diffusion and Navier-slip boundary conditions in a
bounded domain with Lipschitz-continuous second derivatives. After showing
improved regularity of classical solutions, we study their large-time
asymptotics. Specifically we prove that, in suitable norms, the solution
converges to the hydrostatic equilibrium. Moreover, we prove linear stability
for the hydrostatic equilibrium when the temperature is an increasing affine
function of the height, i.e. the temperature is vertically stably stratified.
This work is inspired by results in [Doe+18] for free-slip boundary conditions.
