This paper studies the sweep and ejection events in a channel flow with Re _τ = 80 by using Direct Numerical Simulation (DNS). The effects of ejection and sweep events on the transport of fluid particles are analyzed separately through a quadrant technique. By analyzing trajectories of the particles released at different wall-normal locations, it is found that the particles from the ejection events mainly move upward while the particles from the sweep events move downward of the flow during short and intermediate diffusion time durations. Numerical results show that the effects of the ejection and sweep events on the mean displacement and the mean square dispersion remain for a long time, one-order of magnitude larger than the streamwise Lagrangian integral scales.

中文翻译：

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扫掠和喷射事件对有边界湍流壁中颗粒扩散的影响

本文研究在与信道流中的扫描和喷射事件重新_τ通过使用直接数值模拟（DNS）= 80。通过象限技术分别分析了喷射和吹扫事件对流体颗粒传输的影响。通过分析在不同壁正常位置释放的粒子的轨迹，发现在短时间和中间扩散时间段内，来自喷射事件的粒子主要向上移动，而来自清扫事件的粒子向下移动。数值结果表明，射流和扫掠事件对平均位移和均方色散的影响保持了很长时间，比流向拉格朗日积分尺度大一个数量级。