论文标题
水平剪切的Poiseuille流中的局部湍流层
Localized layers of turbulence in stratified horizontally sheared Poiseuille flow
论文作者
论文摘要
本文介绍了当分层沿垂直方向延伸时，对水平剪切的Poiseuille流中的不稳定性进行了数值分析。我们的研究基于先前的工作，该工作最初通过实验，理论分析和数值模拟\ citep {g21}来检测到这种配置的线性不稳定性。以后，我们将以前的研究扩展到了线性理论之外，并通过直接数值模拟进行了非线性制度。我们注意到，由于谐波共振，该流量通过次要分叉失去了垂直均匀性，并进一步描述了不稳定性阈值附近的这种对称性机制。当离开这个极限时，我们观察到一系列破裂的事件，这些事件将流动分解为由局部剪切不稳定性驱动的无序运动。这种间歇性的动力学导致分层湍流的水平局部层共存，被蜿蜒波浪的静止区域所包围。
This article presents a numerical analysis of the instability developing in horizontally sheared Poiseuille flow, when stratification extends along the vertical direction. Our study builds up on the previous work that originally detected the linear instability of such configuration, by means of experiments, theoretical analysis and numerical simulations \citep{G21}. We extend hereafter this former investigation beyond linear theory, investigating nonlinear regimes with direct numerical simulations. We notice that the flow loses its vertical homogeneity through a secondary bifurcation, due to harmonic resonances, and further describe this symmetry-breaking mechanism in the vicinity of the instability threshold. When departing away from this limit, we observe a series of bursting events that break down the flow into disordered motions driven by localized shear instabilities. This intermittent dynamics leads to the coexistence of horizontal localized layers of stratified turbulence surrounded by quiescent regions of meandering waves.
