PIV計測による都市キャノピー層内外の乱流構造解析(都市・屋内環境,一般講演)

概要

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This study investigates the spatial characteristics of urban-like canopy flow by applying Particle Image Velocimetry (PIV) to the atmospheric turbulence. The study site was a comprehensive outdoor urban scale model site (COSMO), in Japan. The PIV system captured the two dimensional flow field of a street canyon continuously for an hour with a sampling frequency of 30Hz. The focus of the analysis is on a variety of instantaneous turbulent flow structures. One remarkable flow structure is named "flushing", that is a large scale upward motion prevailing across the whole street canyon. They are observed intermittently, and tracer particles are flushed vertically out from the street canyon. Flushing phenomena are also observed in the WT where there is neither thermal stratification nor outer layer turbulence. It is suggested that flushing phenomena are correlated with the passing of large-scale low momentum regions above.
日本流体力学会の論文
2010-09-09