Interplay of waves and eddies in rotating stratified turbulence and the link with kinetic-potential energy partition

Abstract

The interplay between waves and eddies in stably stratified rotating flows is investigated by means of world-class direct numerical simulations using up to 30723 grid points. Strikingly, we find that the shift from vortex- to wave-dominated dynamics occurs at a wave number kR which does not depend on the Reynolds number, suggesting that the partition of energy between wave and vortical modes is not sensitive to the development of turbulence at the smaller scales. We also show that kR is comparable to the wave number at which exchanges between kinetic and potential modes stabilize at close to equipartition, emphasizing the role of potential energy, as conjectured in the atmosphere and the oceans. Moreover, kR varies as the inverse of the Froude number as explained by the scaling prediction proposed, consistently with recent observations and modeling of the Mesosphere–Lower Thermosphere and of the ocean.