Discontinuous Transitions Towards Vortex Condensates in Buoyancy-Driven Rotating Turbulence

TL;DR

This study uses numerical simulations to investigate how rotating buoyant turbulence transitions from 3D flow to a large-scale vortex, revealing discontinuous changes, hysteresis, and abrupt energy transport shifts.

Contribution

It identifies the nature of the transition as discontinuous and uncovers hysteresis and abrupt energy transport changes in the formation of vortex condensates.

Findings

Discontinuous transitions between turbulent states.

Presence of hysteresis in vortex formation.

Abrupt energy transport to the largest mode.

Abstract

Using direct numerical simulations of rotating Rayleigh-B\'enard convection, we explore the transitions between turbulent states from a 3D flow state towards a quasi-2D condensate known as the large-scale vortex (LSV). We vary the Rayleigh number $Ra$ as control parameter and study the system response (strength of the LSV) in terms of order parameters assessing the energetic content in the flow and the upscale energy flux. By sensitively probing the boundaries of the region of existence of the LSV in parameter space, we find discontinuous transitions and we identify the presence of a hysteresis loop as well as memoryless abrupt growth dynamics. We show furthermore that the creation of the condensate state coincides with a discontinuous transition of the energy transport into the largest mode of the system.