Mean flow anisotropy without waves in rotating turbulence

J. A. Brons, P. J. Thomas, A. Potherat

Published 2019-02-21Version 1

We tackle the question of how anisotropy develops in flows subject to background rotation,especially turbulent ones. Inertial waves are generally accepted as the most efficient mechanism to transport energy anisotropically. They have been shown to transfer energy to large anisotropic, columnar structures. Nevertheless, they cannot account for the formation of simpler steady anisotropic phenomena such as Taylor columns. Here, we experimentally show that more than one mechanism involving the Coriolis force may promote anisotropy. In particular, in the limit of fast rotation, that is low Rossby number, the anisotropy of the average of a turbulent rotating flow develops neither as the result of inertial waves nor following the same mechanism as in Taylor columns, but from an interplay between the Coriolis force and average advection.