Generation of large-scale winds in horizontally anisotropic convection

TL;DR

This study simulates three-dimensional horizontally anisotropic convection under rotation, revealing the emergence of strong, turbulent horizontal winds that significantly influence energy distribution and heat flux in the system.

Contribution

It demonstrates that rotation-induced horizontal anisotropy can generate large-scale turbulent winds in convection, a phenomenon not previously well-characterized.

Findings

Strong horizontal winds form under high rotation and temperature difference

Most kinetic energy resides in the horizontal wind

Vertical heat flux decreases with wind development

Abstract

We simulate three-dimensional, horizontally periodic Rayleigh-B\'enard convection between free-slip horizontal plates, rotating about a distant horizontal axis. When both the temperature difference between the plates and the rotation rate are sufficiently large, a strong horizontal wind is generated that is perpendicular to both the rotation vector and the gravity vector. The wind is turbulent, large-scale, and vertically sheared. Horizontal anisotropy, engendered here by rotation, appears necessary for such wind generation. Most of the kinetic energy of the flow resides in the wind, and the vertical turbulent heat flux is much lower on average than when there is no wind.