Thermal Convection in a Rotating Fluid Annulus: Part 2. Classes of Axisymmetric Flow

Abstract

This paper presents the solutions obtained for various axisymmetric thermal convection flows in a rotating annulus. Initially, a solution is obtained for a flow whose interior structure has been observed in detail. A comparison reveals the similarity of the experimental and computed temperature fields and shows the discrepancy to be independent of the computational resolution. On increasing the resolution, the Nusselt number decreases and converges to a value close to that observed. For this particular flow the rotation rate is zero and the flow consists of a direct meridional cell with a large stagnant interior. The associated isotherms lie horizontally in the interior such that the vertical temperature gradient is constant. Secondly, we present solutions of five flows with a rigid surface. These flows cover a wide range of values of the external driving parameters so that physical processes vary from predominately viscous and conduction diffusion to free convection transports. Despite them differences, all five flows exhibit a similar structure, i.e., the interior flows form direct (Hadley) cells with sidewall countercurrents and the zonal flow reverses sign near the center of the fluid. Interpolation of the Nusselt number values yields a (?T/Ω)0.5 dependency. Compared to the Ω?1 dependency of free surface flows, the rigid surface system forms the better transporting mechanism and is less inhibited by rotation.