Phase Transitions in Anisotropic Turbulence

TL;DR

This paper reviews recent research on phase transitions in highly anisotropic turbulence, highlighting how different physical conditions lead to distinct turbulent regimes and the complex behaviors near transition points.

Contribution

It provides a comprehensive survey of recent findings on turbulence phase transitions in anisotropic systems, including thin layers, rotating flows, and fluctuation-induced changes.

Findings

Identification of critical points for turbulence regime changes

Characterization of transitions in thin-layer and rotating turbulence

Insights into fluctuation-induced turbulence phenomena

Abstract

Turbulence is a widely observed state of fluid flows, characterized by complex, nonlinear interactions between motions across a broad spectrum of length and time scales. While turbulence is ubiquitous, from teacups to planetary atmospheres, oceans and stars, its manifestations can vary considerably between different physical systems. For instance, three-dimensional (3D) turbulent flows display a forward energy cascade from large to small scales, while in two-dimensional (2D) turbulence, energy cascades from small to large scales. In a given physical system, a transition between such disparate regimes of turbulence can occur when a control parameter reaches a critical value. The behavior of flows close to such transition points, which separate qualitatively distinct \textit{phases} of turbulence, has been found to be unexpectedly rich. Here, we survey recent findings on such transitions in highly anisotropic turbulent fluid flows, including turbulence in thin layers and under the influence of rapid rotation. We also review recent work on transitions induced by turbulent fluctuations, such as random reversals and transitions between large-scale vortices and jets, among others. The relevance of these results and their ramifications for future investigations are discussed.