The Shear Layer above and in Urban Canopies
The Shear Layer above and in Urban Canopies
复制标题
城市冠层上方和内部的剪切层
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Hanna
中科院分区：
文献类型：
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作者：
P. Huq;A. Carrillo;Louis;A.;White;Jose Redondo;S. Dharmavaram;Steven;R.;Hanna
摘要剪切层的性质和作用，发生在城市树冠的平均建筑物高度水平上，人们对此知之甚少。对速度数据进行了分析，以确定城市冠层剪切层的特征，剪切层定义为高剪切区平均速度剖面的宽广、线性段。在水洞中进行了粒子图像测速测量，以求解算出加州洛杉矶和纽约纽约市两种典型几何形状的城市树冠的速度分布，其高宽比(平均建筑高宽比)H/WB分别为1和3。剪切层随距离的变化不同：当H/WB=1时，城市冠层剪切层从建筑物高度上方迅速延伸至地面，而当H/WB=3时，城市冠层剪切层在建筑物高度附近保持升高，仅在下游达到z/H∼0.5时。平均速度梯度的分布也不同于……
Abstract The nature and role of the shear layer, which occurs at the level of the average building height in urban canopies, are poorly understood. Velocity data are analyzed to determine the characteristics of the shear layer of the urban canopy, defined as the broad, linear segment of the mean velocity profile in a region of high shear. Particle image velocimetry measurements in a water tunnel were undertaken to resolve velocity profiles for urban canopies of two geometries typical of Los Angeles, California, and New York City, New York, for which the aspect ratios (average building height-to-width ratio) H/wb are 1 and 3, respectively. The shear layers evolve with distance differently: For H/wb = 1 the urban canopy shear layer extends quickly from above the building height to ground level, whereas for H/wb = 3 the urban canopy shear layer remains elevated at the vicinity of the building height, only reaching to a depth of z/H ∼ 0.5 far downstream. Profiles of the mean velocity gradient also differ from...