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

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.

漂移波湍流（drift-wave turbulence）与带状流（zonal flows）的基础物理特性，长期以来均依托波动理论（wave-kinetic theory）的框架开展研究。近年来，学界从第一性原理出发重新审视了该理论框架，由此推导出更为精准且仍具可处理性的“改进型”波动方程。尤为关键的是，此类方程揭示了带状流“曲率”（即流动速度的径向二阶导数）对漂移波湍流与带状流的动力学及稳定性的重要影响。本文综述了此类最新研究进展，并基于漂移波湍流的约化模型，整合给出了以准线性为主的带状流物理的高层次统一图景。