THERMAL-CONVECTION IN A ROTATING FLUID ANNULUS BLOCKED BY A RADIAL BARRIER

There have been extensive previous laboratory studies of thermal conve ction in a vertical cylindrical annulus of fluid that rotates about it s axis with angular velocity Omega (say) with respect to an inertial f rame and is subject to an axisymmetric horizontal temperature gradient , as well as associated theoretical and numerical work. The relative f low produced by concomitant buoyancy forces is strongly influenced by Coriolis forces, which give rise to azimuthal circulations and promote , through the process of ''baroclinic instability'', regimes of non-ax isymmetric sloping convection which can be spatially and temporally re gular or irregular (''chaotic geostrophic turbulence''). It is also kn own from previous work that such flows are changed dramatically by the presence of a thin rigid impermeable radial barrier blocking the cros s-section of the annulus, and capable of supporting a net azimuthal pr essure gradient and associated net azimuthal temperature gradient with in the fluid. The presence of the barrier can thus render convective h eat transport across the fluid annulus (as measured by the Nusselt num ber, Nu) virtually independent of Omega (as measured by the so-called Ekman or Taylor number) and dependent only on the Grashof number, G. T he present study reports further systematic determinations of heat tra nsport and of velocity and temperature fields in the presence of a rad ial barrier, with emphasis on the Omega-dependence of the crucially-im portant net azimuthal temperature gradient supported by the barrier an d the physical interpretation of that dependence.