308 透過性円柱の後流構造(2)(OS3-2 噴流,後流,せん断流の構造・普遍的特性(後流2),OS3噴流,後流,せん断流の構造・普遍的特性)

概要

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Particle image velocimetry (PIV) is applied to measurement of airflows around permeable circular cylinders. The aim of this study is to understand the wake structure of a permeable object subjected to uniform flow, such as buildings under construction, steel tower frames, and natural trees. The experimental model of the permeable cylinder is made of squared meshed sheet with a mesh number 32 and an opening ratio of 0.54. The following points are newly found when the flow field is compared to that of a solid cylinder. 1: In case of the permeable cylinder, the turbulence peak appears in a downstream region relative to the solid cylinder, because generation of vortex street is delayed significantly. 2: The drag is not simply estimated only by the opening ratio of the permeable cylinder. 3: The permeable cylinder has non-periodical vortex shedding. This has been confirmed from the correlation coefficient between the enstrophy and the turbulence intensity, which is greater than the solid one.
一般社団法人日本機械学会の論文
2007-11-17