Wave-kinetic approach to zonal-flow dynamics: recent advances

TL;DR

This paper reviews recent advances in wave-kinetic theory for drift-wave turbulence and zonal flows, highlighting improved equations that incorporate zonal-flow curvature effects and their impact on flow stability.

Contribution

It presents a re-examination of wave-kinetic equations from first principles, introducing more accurate models that account for curvature effects in zonal-flow dynamics.

Findings

Improved wave-kinetic equations include zonal-flow curvature effects.

Curvature significantly influences drift-wave and zonal-flow stability.

Recent models offer a more accurate description of turbulence dynamics.

Abstract

Basic physics of drift-wave turbulence and zonal flows has long been studied within the framework of wave-kinetic theory. Recently, this framework has been re-examined from first principles, which has led to more accurate yet still tractable "improved" wave-kinetic equations. In particular, these equations reveal an important effect of the zonal-flow "curvature" (the second radial derivative of the flow velocity) on dynamics and stability of drift waves and zonal flows. We overview these recent findings and present a consolidated high-level picture of (mostly quasilinear) zonal-flow physics within reduced models of drift-wave turbulence.