Influence of wall modes on the onset of bulk convection in a rotating cylinder

The onset of thermal convection in an enclosed rotating cylinder is greatly influenced by the interaction between the Coriolis force and the cylinder sidewall. For temperature differences between the hot bottom and the cool top that are too small to sustain convection throughout the entire cylinder, convection sets in as pairs of wall-bounded hot thermal plumes ascend and cold thermal plumes descend in the sidewall boundary layer, the so-called wall modes of rotating convection. Over an extensive range of parameter space, several wall modes with different numbers of thermal pairs coexist stably, and this multiplicity of states leads to very rich nonlinear dynamics as the temperature difference is increased to a level supporting thermal convection throughout the bulk of the cylinder. The bulk convection takes on characteristics of Koppers-Lortz spatiotemporal chaos, but its interaction with the persistent wall modes also leads to further flow complications which are explored here via numerical simulations. (C) 2008 American Institute of Physics.