発達チャンネル乱流の乱れ特性に対するレイノルズ数の影響〔流体工学, 流体機械〕

概要

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Hot wire measurements of a streamwise velocity component were carried out in a fully developed turbulent channel flow under an isothermal steady condition. Reynolds number of flow varied from 8000 to 40000 (Re_r=190〜617). The aspect ratio of channel is 3 : 1. We focused an attention to the effect of Reynolds number on the characteristics of velocity fluctuation in the near wall region. As a result of investigation, it is clear that the universal profile of non-dimensional velocity turbulence intensity in the viscous layer is independent of Reynolds number. The universality is also gotten in distributions of the skewness and the flatness factors of turbulence in the viscous layer. From the universality, we propose the empirical relation, u_<rms>^+=Σa_n×(Log Y^+)^n, in the viscous layer, Y^+<50.
1998-04-25