Transient Convective Spin-Up Dynamics

We study numerically the formation and breakdown of transient axisymmetric rings of up- and down-welling fluid in impulsively started rotating Rayleigh Benard convection. First observed in laboratory experiments with constant negative heat flux at the top boundary [1-3], these rings form during spin-up for a range of Taylor and Rossby (or flux Rossby) numbers, eventually breaking down into a grid of cyclonic vortices with descending flow surrounded by slowly ascending flow. The formation and longevity of the rings depends on the Prandtl number $Pr$, with no sustained rings forming for $Pr