Minimal transition thresholds in plane Couette flow
Minimal transition thresholds in plane Couette flow
复制标题
平面库埃特流中的最小转变阈值
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
D. Henningson
中科院分区：
文献类型：
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作者：
Y. Duguet;Antonios Monokrousos;L. Brandt;D. Henningson
亚临界过渡到湍流需要有限振幅扰动。使用非线性优化技术在一个周期性的计算域中，我们确定的扰动平面Couette流过渡与最小的初始动能为雷诺数3000。我们提出了一个新的标度律Ec = O（Re-2.7）的能量阈值与雷诺数，在定量上与实验估计的管流。对于Re = 1500，详细分析了与这种空间局部扰动相关的湍流路线。几个已知的机制被发现发生一个接一个：奥尔机制，斜波相互作用，提升，条纹弯曲，条纹崩溃，展向扩展。条纹故障的现象进行了分析，在领先的有限时间李雅普诺夫指数相关的边缘轨迹。
Subcritical transition to turbulence requires finite-amplitude perturbations. Using a nonlinear optimisation technique in a periodic computational domain, we identify the perturbations of plane Couette flow transitioning with least initial kinetic energy for Re ⩽ 3000. We suggest a new scaling law Ec = O(Re−2.7) for the energy threshold vs. the Reynolds number, in quantitative agreement with experimental estimates for pipe flow. The route to turbulence associated with such spatially localised perturbations is analysed in detail for Re = 1500. Several known mechanisms are found to occur one after the other: Orr mechanism, oblique wave interaction, lift-up, streak bending, streak breakdown, and spanwise spreading. The phenomenon of streak breakdown is analysed in terms of leading finite-time Lyapunov exponents of the associated edge trajectory.