Turbulence Measurements in Open‐Channel Flows over Artificial Bed Forms
Turbulence Measurements in Open‐Channel Flows over Artificial Bed Forms
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DOI：
10.1061/(asce)0733-9429(1993)119:3(306
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发表时间：
1993-03
影响因子：
2.4
通讯作者：
D. Lyn
中科院分区：
文献类型：
--
作者：
D. Lyn
采用双分量激光多普勒测速仪测量了人工固定一维周期性河床特征上方恒定平均水深的均匀明渠流的平均和湍流特性。研究了两种基于三角形单元的床面形状，三角形单元的高度（λ\N为水流深度的20%）和波长（λ\N为高度的12.5倍）相同，但形状不同：（1）由平坦区域分隔的45°三角形脊;（2）三角形单元近似沙丘，上游面为轻度倾斜，而不是平坦区域。总剪切速度的作用，平均能量斜率和平均流深的基础上，作为一个可能的速度尺度进行了研究。对于远离床的流动区域，速度亏损和雷诺剪应力剖面通常与平板剖面很好地近似。足够远的回流区和再附着区，湍流特性崩溃相当不错，当缩放与总剪切速度在大部分的深度，但不遵循在流动的下部的平板行为。探讨了清水测量对描述悬浮泥沙浓度剖面和总悬浮负荷计算的可能影响。
Measurements of mean and turbulence characteristics in uniform open-channel flows of constant mean depth over artificial fixed one-dimensional periodic bed features were obtained using two-component laser-Doppler velocimetry. Two types of bed forms, based on triangular elements of the same height (≈\N 20% of the flow depth) and wavelength (≈\N 12.5 times the height) but of different shape, were studied: (1) 45° triangle ridges separated by a flat region; and (2) triangular elements approximating dunes with a mildly sloping upstream face instead of a flat region. The role of the total shear velocity, based on the mean energy slope and the mean flow depth, as a possible velocity scale is studied. Velocity defect and the Reynolds shear stress profiles were generally well approximated by the flat-bed profiles for regions of flow far from the bed. Sufficiently far from the recirculation and reattachment zones, turbulence characteristics collapsed fairly well when scaled with the total shear velocity over most of the depth, but do not follow the flat-bed behavior in the lower part of the flow. Possible implications of the clear-water measurements for the description of suspended sediment concentration profiles and total suspended load computations are explored.