Suspended sediment concentration and the ripple–dune transition
Suspended sediment concentration and the ripple–dune transition
复制标题
悬浮泥沙浓度和波纹-沙丘转变
DOI：
10.1002/hyp.1505
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发表时间：
2004
影响因子：
3.2
通讯作者：
A. Robert
中科院分区：
文献类型：
--
作者：
R. Schindler;A. Robert
进行水槽实验是为了监测波纹-沙丘过渡的七个阶段以及床面上方三个不同位置的流动湍流强度和悬浮沉积物浓度的变化。使用声学多普勒测速仪（ADV）获得三维速度测量。使用 ADV 信号幅度间接监测悬浮沉积物浓度 (SSC)。尽管仅限于时间平均参数，但分析表明，SSC 随过渡阶段和采样高度的变化而显着变化。统计分析还揭示了在从波纹到沙丘过渡的关键阶段，在水流深度的下半部分，悬浮泥沙浓度随床面高度的变化存在明显的均匀性。这也是湍流强度最大化的阶段。在悬浮泥沙浓度和垂直速度波动的均方根值之间也观察到了统计学上显着的相关性。这些相关性反映了剪切层活动的不同水平以及过渡过程中不同的湍流区域。相反，雷诺剪切应力的时间平均值与悬浮泥沙浓度的关系非常弱。版权所有 © 2004 约翰·威利父子有限公司
Flume experiments were conducted in order to monitor changes in flow turbulence intensity and suspended sediment concentration at seven stages across the ripple–dune transition and at three different positions above the bed surface. Three‐dimensional velocity measurements were obtained using an acoustic Doppler velocimeter (ADV). Suspended sediment concentration (SSC) was monitored indirectly using ADV signal amplitude. Although limited to time‐averaged parameters, the analysis reveals that SSC varies significantly with stage across the transition and with sampling height. The statistical analysis also reveals an apparent uniformity of suspended sediment concentration with height above the bed in the lower half of the flow depth at the critical stage in the transition from ripples to dunes. This is also the stage at which turbulence intensity is maximized. Statistically significant correlations were also observed between suspended sediment concentrations and root‐mean‐square values of vertical velocity fluctuations. These correlations reflect the various levels of shear‐layer activity and the distinct turbulent flow regions across the transition. Conversely, time‐averaged values of Reynolds shear stress exhibit a very weak relationship with suspended sediment concentrations. Copyright © 2004 John Wiley & Sons, Ltd.