Effects of shear flows on the evolution of fluctuations in interchange turbulence

TL;DR

This study investigates how different shear flows influence the evolution of vorticity and density fluctuations in interchange turbulence, revealing distinct effects of streamers and zonal flows on transport and oscillation behaviors.

Contribution

It provides a non-perturbative analysis of shear flow impacts on turbulence, highlighting differences between streamers and zonal flows in fluctuation suppression and oscillation dynamics.

Findings

Density transport is less reduced by streamers than by zonal flows.

Zonal flows cause oscillation death at the same shear strength.

Vorticity grows and density decays as power laws, with exponential growth/decay when combined shear effects are present.

Abstract

We report a non-perturbative study of the effect of different type of shear flows on the evolution of vorticity and particle density fluctuations in interchange turbulence. For the same shear strength, the transport of density is less reduced by streamers than by zonal flows, zonal flows leading to oscillation death. In the inviscid limit, vorticity (density) grows (decays) as a power law due to streamer or zonal flow, and exponentially due to the combined effect of zonal flow and streamer with the same sign of shear. Zonal flow and streamer with the opposite sign of shear lead to oscillation at multiple frequencies.