Open Access

REVIEW

Solitons-Like Coherent Structures in Shear Flows

Ning Hu, Cunbiao Lee^*

State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing, 100871, China

* Corresponding Author: Cunbiao Lee. Email:

(This article belongs to the Special Issue: Traveling Waves, Impulses and Laminar-turbulent Transitions in Fluid Dynamics Equations)

Fluid Dynamics & Materials Processing 2025, 21(10), 2389-2417. https://doi.org/10.32604/fdmp.2025.067248

Received 28 April 2025; Accepted 22 September 2025; Issue published 30 October 2025

Abstract

The formation, evolution, and dynamics of flow structures in wall-bounded turbulence have long been central themes in fluid-mechanics research. Over the past three decades, Soliton-like Coherent Structures (SCSs) have emerged as a ubiquitous and unifying feature across a wide range of shear flows, including K-type, O-type, N-type, and bypass transitional boundary layers, as well as fully developed turbulent boundary layers, mixing layers, and pipe flows. This paper presents a systematic review of the fundamental properties of SCSs and highlights their fundamental role in multiple transition scenarios. The analysis further explores the connection between SCSs and low-speed streaks, offering insight into their coupled dynamics. The phenomenon of turbulent bursting is also examined within the context of SCS dynamics. Together, these studies underscore the potential of SCSs to serve as a coherent dynamical framework for understanding turbulence generation mechanisms in wall-bounded flows. Finally, the review extends to the manifestation of SCSs in other canonical flows, including mixing layers, stratified shear flows, and jets, confirming their universality and significance in fluid dynamics. These findings not only advance our understanding of turbulence generation but also offer a promising theoretical foundation for future research in transitional and turbulent flows.

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