Experimental observation of the geostrophic turbulence regime of rapidly rotating convection

TL;DR

This study experimentally observes the geostrophic turbulence regime in rapidly rotating convection, confirming theoretical scaling laws and highlighting the sensitivity of heat transport efficiency to heat source distribution.

Contribution

First experimental validation of the geostrophic turbulence regime in rapidly rotating convection, aligning with numerical simulations and revealing sensitivity to heat source distribution.

Findings

Heat transport measurements agree with geostrophic turbulence scaling laws.

Scaling exponent matches theoretical predictions.

Heat transport prefactor varies with heat source distribution.

Abstract

The competition between turbulent convection and global rotation in planetary and stellar interiors governs the transport of heat and tracers, as well as magnetic-field generation. These objects operate in dynamical regimes ranging from weakly rotating convection to the `geostrophic turbulence' regime of rapidly rotating convection. However, the latter regime has remained elusive in the laboratory, despite a worldwide effort to design ever-taller rotating convection cells over the last decade. Building on a recent experimental approach where convection is driven radiatively, we report heat transport measurements in quantitative agreement with this scaling regime, the experimental scaling-law being validated against direct numerical simulations (DNS) of the idealized setup. The scaling exponent from both experiments and DNS agrees well with the geostrophic turbulence prediction. The prefactor of the scaling-law is greater than the one diagnosed in previous idealized numerical studies, pointing to an unexpected sensitivity of the heat transport efficiency to the precise distribution of heat sources and sinks, which greatly varies from planets to stars.