開水路流れにおける乱れのスペクトル特性について

Abstract

The spectral characteristics of the turbulent energy and the Reynolds stress in a two-dimen-sional free surface shear flow are experimentally investigated, using hot-film flowmeters.Experimental results show that the turbulence in a free surface flow is multi-structual, thatis, it depends on the depth of flow, the width of channel and so on. The turbulent energyspectrum, whose structure is considered to be controlled by the depth, is approximated by aconstant in the production subrange, -5/3 power law in the inertial subrange and -3 or -7power law in the viscous subrange, respectively. The larger Froude number, the smaller thespectral constant in the viscous subrange becomes while that in the inertial subrange can betreated as a universal constant. Through the dimensional consideration, the Reynolds stressspectrum may be represented by a constant in the production subrange and -7/3 or -3 powerlaw in the inertial subrange.