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arXiv · 1408.6483

Inverse cascade and symmetry breaking in rapidly-rotating Boussinesq convection

B. Favier·L. J. Silvers·M. R. E. Proctor
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Abstract

In this paper we present numerical simulations of rapidly-rotating Rayleigh-B\'enard convection in the Boussinesq approximation with stress-free boundary conditions. At moderately low Rossby number and large Rayleigh number, we show that a large-scale depth-invariant flow is formed, reminiscent of the condensate state observed in two-dimensional flows. We show that the large-scale circulation shares many similarities with the so-called vortex, or slow-mode, of forced rotating turbulence. Our investigations show that at a fixed rotation rate the large-scale vortex is only observed for a finite range of Rayleigh numbers, as the quasi-two-dimensional nature of the flow disappears at very high Rayleigh numbers. We observe slow vortex merging events and find a non-local inverse cascade of energy in addition to the regular direct cascade associated with fast small-scale turbulent motions. Finally, we show that cyclonic structures are dominant in the small-scale turbulent flow and this symmetry breaking persists in the large-scale vortex motion.

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B. Favier, L. J. Silvers, M. R. E. Proctor. 2014-08-27. Inverse cascade and symmetry breaking in rapidly-rotating Boussinesq convection. https://doi.org/10.1063/1.4895131

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