Turbulent flow similarity over an array of cubes in near-neutrally stratified atmospheric flow
Turbulent flow similarity over an array of cubes in near-neutrally stratified atmospheric flow
复制标题
近中性分层大气流中立方体阵列上的湍流相似性
DOI：
10.1017/s0022112008003765
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发表时间：
2008
影响因子：
3.7
通讯作者：
M. Kanda
中科院分区：
文献类型：
--
作者：
A. Inagaki;M. Kanda
本研究的主要目的是检验近壁湍流的内层标度相似性的鲁棒性。感兴趣的湍流边界层是在一个非常粗糙的表面上，具有非常高的雷诺数和显着的外层扰动。这与实验室研究的典型湍流不一致，但在城市地区很常见。调查是使用综合室外比例模型（COSMO）设施。COSMO是由一个50×100 m2的平面混凝土基础上的1.5 m混凝土立方体组成的规则阵列。这种独特的设施，使我们能够获得湍流数据集内的垂直恒定应力区在近中性分层在高雷诺数。从COSMO的湍流谱和速度波动的标准偏差进行了比较，在农村和城市的表面，并在风洞实验中获得的值。结果表明，内层尺度相似性对壁面法向波动和雷诺应力具有鲁棒性，与粗糙度类型和外层条件无关。由于外层扰动的影响，水平速度脉动的内层标度相似性失效。在水平速度波动中，外层湍流对内层尺度涡的相对重要性被成功地量化在由外层尺度归一化的粗糙度尺度方面。
The main objective of this study is to examine the robustness of the inner-layer scaling similarity of near-wall turbulence. The turbulent boundary layer of interest is over a very rough surface with a very high Reynolds number and significant outer-layer disturbances. This is not consistent with the canonical turbulent flows studied in laboratories, but it is common in urban areas. The investigation was conducted using the comprehensive outdoor scale model (COSMO) facility. COSMO is composed of a regular array of 1.5 m concrete cubes on a 50×100 m2 flat concrete base. This unique facility allows us to obtain the turbulent dataset within the vertical constant stress region under near-neutral stratification at high Reynolds numbers. The turbulent spectra and the standard deviation of velocity fluctuations from COSMO were compared with the values obtained over rural and urban surfaces, and in wind-tunnel experiments. The results confirmed that the inner-layer scaling similarity was robust for the wall-normal fluctuations and the Reynolds stress, independent of the roughness types and the outer-layer conditions. The inner-layer scaling similarity failed for the horizontal velocity fluctuations owing to the influence of the outer-layer disturbance. The relative importance of outer-layer turbulence to inner-layer-scale eddies in the horizontal velocity fluctuations was successfully quantified in terms of the roughness scale normalized by the outer-layer scale.