Numerical studies into the dynamics of non-spherical particles in turbulent channel flow have, until now, been mostly confined to low Reynolds numbers. In this paper, we investigate the dynamics of tracer non-spherical particles in a channel flow at for the first time. Tracer spheroidal particles suspended in a turbulent channel flow are computed by means of direct numerical simulation coupled with a Lagrangian point-particle approach. We examine the rotational dynamics and alignment of tracer spheroids of different aspect ratio in both the near-wall region and, in particular, the quiescent core which is not observed at lower Reynolds numbers. In the near-wall region, the effect of Reynolds number on preferential alignment is negligible with particle rotation exhibiting a weak dependence for all aspect ratios investigated. However, the particle rotation is strongly damped in the quiescent core demonstrating that the motion of tracer spheroids becomes quiescent. The striking difference in spheroids' rotational dynamics observed inside and outside of the quiescent core is correlated with the local Kolmogorov time scale in the core and outside of it.

中文翻译：

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静止核心对湍流通道流中示踪球体粒子动力学的影响

迄今为止，对湍流通道流中非球形粒子动力学的数值研究主要局限于低雷诺数。在本文中，我们首次研究了通道流中示踪剂非球形粒子的动力学。悬浮在湍流通道流中的示踪球体粒子是通过直接数值模拟结合拉格朗日点粒子方法计算的。我们检查了近壁区域中不同纵横比的示踪球体的旋转动力学和对齐，特别是在较低雷诺数下未观察到的静止核心。在近壁区域，雷诺数对优先排列的影响可以忽略不计，粒子旋转对所有研究的纵横比都表现出弱依赖性。然而，静止核心中的粒子旋转受到强烈阻尼，这表明示踪球体的运动变得静止。在静止核心内部和外部观察到的球体旋转动力学的显着差异与核心内部和外部的局部 Kolmogorov 时间尺度相关。