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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Sand particle velocities over a subaqueous dune slope using high-frequency image capturing
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Sand particle velocities over a subaqueous dune slope using high-frequency image capturing

机译：使用高频图像捕获在水粒速度下的砂颗粒速度

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摘要

This work presents measurements and analysis of sand particle velocities over a subaqueous dune with median sand diameter of 0.85 mm. Time-lapse images of the mobile bed and an automated particle image velocimetry (PIV)-based cross-correlation method are used to obtain mean velocity of sand particles. This technique is shown to be consistent with measurements obtained with manual tracing. The measurements indicate an increase in mean particle velocity over a dune slope. Three regions are distinguished over the dune slope: (1) region of fluctuating particle velocity, (2) region of increasing particle velocity, and (3) region of maximum particle velocity. The observations are aligned with experimental and numerical modelling studies, indicating fluctuations in flow velocity over a dune stoss slope. We furthermore show that the standard deviation of the mean particle velocity is affected by the slope location and decreases from the lower slope towards the upper slope. The particle velocity variability is discussed in the context of general onset and cessation of sediment transport, the effect of the reattachment zone, sweep-transport events, and the existence of superimposed bedforms. With this work we bridge the gap between measurements of bedload transport at the particle-scale and at the bedform-scale. (c) 2019 John Wiley & Sons, Ltd.
机译：这项工作介绍了砂颗粒速度的测量和分析水粒速度，中间砂直径为0.85毫米。基于移动床的时间流逝图像和自动粒子图像测速法（PIV）的基于互相关方法，用于获得砂颗粒的平均速度。该技术显示与用手动跟踪获得的测量结果一致。测量结果表明沙丘斜坡上的平均颗粒速度的增加。在沙丘斜坡上区分三个区域：（1）波动颗粒速度的区域，（2）颗粒速度增加的区域，和（3）最大颗粒速度的区域。观察结果与实验和数值建模研究一致，表明在沙丘坡度上的流速波动。此外，我们表明，平均粒子速度的标准偏差受斜坡位置的影响，并且从下斜率朝向上斜率的下斜率降低。在一般发作和沉积物传输的情况下讨论了颗粒速度变化，重新连接区，扫描输送事件的效果和叠加床形的存在。通过这项工作，我们弥合了粒度和朝向磁砖尺度的床单输送测量之间的差距。 （c）2019 John Wiley＆Sons，Ltd。

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