Evidence for the influence of form drag on bottom boundary layer flow
Evidence for the influence of form drag on bottom boundary layer flow
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DOI：
10.1029/jc087ic06p04148
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发表时间：
1982-05
影响因子：
--
通讯作者：
T. M. Chriss;D. Caldwell
中科院分区：
文献类型：
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作者：
T. M. Chriss;D. Caldwell
Smith [1977]和Smith和姆克林[1977]证明，多个粗糙度尺度可以产生两个以上段的速度剖面。因此，当形状阻力很重要时，常应力假设就不成立了.在早先的一篇论文中[考德威尔和克里斯，1979]，我们证明了底边界层中粘性子层的存在，并发现在它上面有一个对数层。在检验实验的附加数据时，在对数区发现分段剖面（图1和2），正如所预料的那样，如果形状阻力影响流动的话。当重新分析原始数据集时，在剖面的上部使用较薄的平均间隔，并同时包含向上和向下的遍历，它也显示出两个不同的对数斜率。(In在最初的研究中，只使用了向下的遍历。）虽然与单个对数形式的偏差不一定很大，但对数回归的斜率在两个区域中明显不同，这意味着上方的湍流应力明显大于靠近床的湍流应力。
posed of two intersecting segments, Smith [1977] and Smith and McLean [1977] demonstrate that multiple roughness scales can generate velocity profiles with more than two segments. Thus when form drag is important the constantstress assumption will not be valid. In an earlier paper [Caldwell and Chriss, 1979], we demonstrated the existence of the viscous sublayer in the bottom boundary layer and found a logarithmic layer above it. In examining additional data from the experiment, segmented profiles were found in the logarithmic region (Figures 1 and 2), as expected if form drag influences the flow. When the original data set was reanalyzed, using thinner averaging intervals in the upper portion of the profile and also incorporating both upward and downward traverses, it too shows two distinct logarithmic slopes. (In the original study, only downward traverses were used.) Although deviation from a single logarithmic form is not necessarily large, the slope of the logarithmic regression is significantly different in the two regions, implying that the turbulent stress above is significantly larger than it is nearer the bed.