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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Comparing different methods of bed shear stress estimates in simple and complex flow fields
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Comparing different methods of bed shear stress estimates in simple and complex flow fields

机译：比较简单流场和复杂流场中不同的床层切应力估算方法

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摘要

Bed shear stress is a fundamental variable in river studies to link flow conditions to sediment transport. It is, however, difficult to estimate this variable accurately, particularly in complex flow fields. This study compares shear stress estimated from the log profile, drag, Reynolds and turbulent kinetic energy (TKE) approaches in a laboratory flume in a simple boundary layer, over plexiglas and over sand, and in a complex flow field around deflectors. Results show that in a simple boundary layer, the log profile estimate is always the highest. Over plexiglas, the TKE estimate was the second largest with a value 30 per cent less than the log estimate. However, over sand, the TKE estimate did not show the expected increase in shear stress. In a simple boundary layer, the Reynolds shear stress seems the most appropriate method, particularly the extrapolated value at the bed obtained from a turbulent profile. In a complex flow field around deflectors, the TKE method provided the best estimate of shear stress as it is not affected by local streamline variations and it takes into account the increased streamwise turbulent fluctuations close to the deflectors. It is suggested that when single-point measurements are used to estimate shear stress, the instrument should be positioned close to 0(.)1 of the flow depth, which corresponds to the peak value height in profiles of Reynolds and TKE shear stress. Copyright (C) 2004 John Wiley Sons, Ltd.
机译：河床剪切应力是河流研究中将流量条件与泥沙输送联系起来的基本变量。但是，很难准确估计此变量，尤其是在复杂的流场中。这项研究比较了在简单的边界层，有机玻璃和沙子上以及偏转器周围复杂流场中的实验室水槽中，通过测井曲线，阻力，雷诺和湍动能（TKE）方法估算的切应力。结果表明，在简单的边界层中，测井剖面估计值始终是最高的。与有机玻璃相比，TKE估算值排名第二，比对数估算值低30％。但是，在沙地上，TKE估算值并未显示出预期的剪应力增加。在简单的边界层中，雷诺剪切应力似乎是最合适的方法，尤其是从湍流剖面获得的床层外推值。在偏流器周围的复杂流场中，TKE方法提供了最佳的切应力估算值，因为它不受局部流线变化的影响，并且考虑了靠近偏流器的沿流向湍流波动的增加。建议当使用单点测量来估计切应力时，仪器应放置在接近流动深度0（。）1的位置，这与雷诺和TKE切应力曲线中的峰值高度相对应。版权所有（C）2004 John Wiley Sons，Ltd.

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