ROTATIONAL EFFECTS IN TURBULENCE DRIVEN BY CONVECTION

We analyze rotational effects in turbulence driven by convection in th e outer regions of an accretion disk, where opacity is mainly given by ice. These effects are explicitly considered through the introduction of an efficiency factor which takes into account inverse energy casca de processes and through the consideration of a centrifugally supporte d basic state. By adopting a procedure which assigns some dynamics to the anisotropy factor, we obtain an equation that describes how the tu rbulent structures behave along the disk. Stationary solutions to that equation are only found if the accretion rate, the efficiency factor, the rotational intensity and the Brunt-Vaisala frequency satisfy a kn own critical condition. If the rotational intensity is below the criti cal one, there are two branches of solutions for that equation. If the accretion rate is not very high, the effective Rayleigh number for th e onset of the convective instability decreases and, in the upper bran ch, longitudinal scales are always greater than the horizontal scales; in the lower branch, as we approach the surface of the disk, horizont al scales become greater than longitudinal ones. In both branches, cen trifugal effects prevail over the effects due to the Coriolis force. I f the accretion rate is high, the effective Rayleigh number for the on set of the convective instability increases. In the lower branch, the size of the turbulent structures increases as z --> 1; in the upper br anch, the size of the turbulent structures decreases as z --> 1. In th e lower branch, generation of waves occurs all long the disk. In the u pper branch, it is confined to regions close to the point where convec tion sets in. For those high values of the accretion rate, the effects due to the Coriolis force prevail over the those due to the centrifug al forces.