Channel flow turbulence exhibits interesting spatiotemporal complexities at transitional Reynolds numbers. In this paper, we investigated some aspects of the kinematics and dynamics of fully localized turbulent bands in large flow domains. We discussed the recent advancement in the understanding of the wave-generation at the downstream end of fully localized bands. Based on the discussion, we proposed a possible mechanism for the tilt direction selection. We measured the propagation speed of the downstream end and the advection speed of the low-speed streaks in the bulk of turbulent bands at various Reynolds numbers. Instead of measuring the tilt angle by treating an entire band as a tilted object as in prior studies, we proposed that, from the point of view of the formation and growth of turbulent bands, the tilt angle should be determined by the relative speed between the downstream end and the streaks in the bulk. We obtained a good agreement between our calculation of the tilt angle and the reported results in the literature at relatively low Reynolds numbers.

中文翻译：

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通道流中低雷诺数湍流带的运动学和动力学

通道流动湍流在过渡雷诺数下表现出有趣的时空复杂性。在本文中，我们研究了大流动域中完全局部湍流带的运动学和动力学的某些方面。我们讨论了对完全局部化波段下游端的波浪生成理解的最新进展。基于讨论，我们提出了一种可能的倾斜方向选择机制。我们测量了下游端的传播速度和不同雷诺数下大量湍流带中低速条纹的平流速度。我们没有像先前的研究那样通过将整个带视为倾斜物体来测量倾斜角，而是从湍流带的形成和增长的角度提出，倾斜角度应由下游端与散装条纹之间的相对速度决定。在相对较低的雷诺数下，我们在倾斜角的计算与文献中报告的结果之间获得了很好的一致性。