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优秀论文  
Turbulent bursting and sediment resuspension in hyper-eutrop
发布人:lyp    发布时间:2018-09-05 15:24    访问次数:

Abstract
Turbulent bursting plays a crucial role in sediment resuspension and transportation in many shallow lakes. This study analyzed the relationships between coherent structures and sediment resuspension in regions with and without intense wind waves in Lake Taihu. Acoustic Doppler Velocimetry (ADV) and Optical Backscatter Sensor (OBS) were used to measure field data sets including flow velocities and intense wind waves respectively. The results showed that the intermittent bursting events contributed significantly to the processes of momentum and sediment exchanges. Turbulent bursting effectively controlled the three patterns of sediment suspension during the 512s observation period. In the windy region, the bursting motions, i.e. “ejection” and “sweep” events mainly accounted for the Reynolds stress generation and made major contribution to sediment resuspension. While in the current-dominant region, turbulent mixing from inward and outward interactions overwhelmed other processes. The vertical sediment fluxes reduced by an order of magnitude due to the less effect of wind waves and the lack of upwelling currents. It is therefore important to study turbulent coherent structures and sediment resuspension to understand the spatio-temporal and frequency characteristics of bursting events.
 
摘要:
紊流猝发在浅水湖泊沉积物再悬浮和输运中有着至关重要的作用。本研究分析了太湖强、弱风浪区相干结构与泥沙再悬浮的关系。利用声学多普勒测(ADV)和光学后向散射传感器(OBS)分别测量了包括流速和风浪数据。结果表明,间歇性猝发事件对泥沙动量和交换过程有重要贡献。在512秒观测期间,紊流猝发以三种模式有效控制泥沙悬浮。在强风浪区,“喷射”和“扫掠”事件是雷诺应力的主要贡献者,对泥沙再悬浮有重要驱动作用。而在湖流主导区域,来自内外相互作用的湍流混合压制了其他过程。由于风浪的影响较小且缺乏上升流,垂向泥沙通量相对减少了一个数量级。

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