Transitional–turbulent spots bridge the deterministic laminar state with the stochastic turbulent state and affect the transition zone length in engineering flows. Turbulent spot research over the past four decades has expanded from incompressible flat-plate boundary layer and pipe flow to hypersonic boundary layer flow, turbomachinery flow, channel flow, plane Couette flow, and a range of more complex flows. Progress has been made on the origination, composition, demarcation, growth, mutual interaction, reproduction, sustainability, and self-organization of turbulent spots. The hypothesis that transitional–turbulent spots are a basic module of the fully turbulent boundary layer has been proven through the discovery of locally generated turbulent–turbulent spots dominating the wall layer. Splitting of transitional–turbulent spots in pipe flow has been linked to a life cycle localized in the spot frontal section. This review discusses these advances and outlines future research directions.

中文翻译：

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对动荡地区的新见解


过渡-湍流点将确定性层流状态与随机湍流状态联系起来，并影响工程流中的过渡区长度。过去四十年的湍流点研究已经从不可压缩平板边界层和管道流扩展到高超声速边界层流、涡轮机械流、通道流、平面库埃特流以及一系列更复杂的流动。在湍流点的起源、组成、划分、生长、相互作用、繁殖、可持续性和自组织方面已经取得了进展。通过发现主导壁层的局部生成的湍流-湍流点，证明了过渡-湍流点是完全湍流边界层的基本模块的假设。管道流中过渡-湍流点的分裂与点锋面部分的生命周期有关。这篇综述讨论了这些进展并概述了未来的研究方向。