Filed Observation in Urban Boundary Layer and a New Similarity Law

城市边界层实地观测与新相似律

• 批准号: 12450197
• 负责人: KANDA Manabu
• 金额: $ 9.92万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450197/
• 关键词: Urban bouadary layer; Turbulent transfer; Scalar; Filed observation; Wavelet analysis; Similarity function; 乱流拡散; スカラー輸送; モニン-オブコフ相似則; インバランス問題; 物質拡散

A long-term flux measurement of momentum, heat, moisture and CO_2 has been conducted in densely-built up residential area in Tokyo. Consequently, new similarity functions of flux, deviation and dissipation related to turbulent flow have been proposed. Moreover, the detailed mechanism of turbulent exchange process over a complicated urban geometry has been investigated through wavelet analysis and the following results were obtained. (l) The turbulent characteristics showed a significant diurnal variation. Particularly in the morning, large scale turbulent organized structure extending to boundary layer height entrained the upper air, resulting in the similar transfer of momentum, heat, moisture and C0_2. (2) Turbulent organized structures generated by shear-instability and thermal instability make dominant role on turbulent transport. They transfer heat, moisture, and CO_2 in different efficiency. The turbulent transfer of heat is most effective. One of the reasons is that the surface-heterogeneity of temperature is smaller than those of moisture and CO_2, and another possibility is that heat is the active scalar of direct generation of thermal plumes.

在东京密集居住区进行了动量、热量、湿度和CO_2通量的长期测量。在此基础上，提出了与湍流有关的通量、偏差和耗散的新的相似函数。此外，本文还利用小波分析方法研究了复杂城市地形上湍流交换过程的详细机制，得到了以下结果。(l)湍流特征表现出明显的日变化。特别是在早晨，大尺度的湍流有组织的结构延伸到边界层高度夹带高层空气，导致类似的动量，热量，水分和CO_2的传输。(2)由剪切不稳定性和热不稳定性产生的湍流组织结构对湍流输运起主导作用。它们以不同的效率传递热量、水分和CO_2。湍流传热是最有效的。其原因之一是温度的地表非均匀性小于水汽和CO_2的地表非均匀性，另一种可能是热量是热羽流直接生成的活跃标量。