The Navier-Stokes equation driven by heat conduction is studied.
It is proven that if the driving force is small then the solutions
of the Navier-Stokes equation are ultimately regular. As a
prototype we consider Rayleigh-Bénard convection, in the
Boussinesq approximation. Under a large aspect ratio assumption,
which is the case in Rayleigh-Bénard experiments with Prandtl
numer close to one, we prove the ultimate existence and regularity
of a global strong solution to the 3D Navier-Stokes equation
coupled with a heat equation, and the existence of a maximal
$\mathcal B$-attractor. Examples of simple $\mathcal B$-attractors
from pattern formation are given and a method to study their
instabilities proposed.