On the influence of centrifugal buoyancy on rotating convection

Centrifugal buoyancy forces in a container rotating about an axis aligned w ith gravity lead to mean flows that interact with rotating convection. A mo del of the interactions between these flows and the thermal instabilities t hat occur in weakly nonlinear rapidly rotating convection is used to estima te when, in terms of external parameters, centrifugal buoyancy has a substa ntial influence on thermal convective instability. The significant physical effects include the direct action of centrifugal buoyancy on the eddies th emselves, the upwards advection of basic-state vertical shear by the pertur bation rolls, and the alteration of the mean thermal stratification upon wh ich eddies grow by the basic centrifugally induced circulation. It is shown that the first effect is the most important for common laboratory settings , and can lead to destabilization of the system at outer radii. Other manif estations of centrifugal buoyancy include the generation of a positive offs et of the mean temperature at the centre of the cell, and a reduction of th is offset by heat fluxes arising from the centrifugally modified finite-amp litude convective eddies.