開水路流れの乱流構造

Abstract

The outline of the recent investigations on the turbulence characteristics in free surface shearflows, performed by the staffs in the Ujigawa Hydraulics Laboratory, is described in this paper, which is consisted of the following two main parts.Firstly, the spectral similarities of the turbulence energy, the Reynolds stress and the con-vective process are obtained for the productive, the inertial and the viscous subrange respective-ly, through the technique of dimensional analysis. The validity of these similarities are examinedby the experimental data.Secondly, the vertical distribution of parameters on fhe turbulence field in a two-dimensionalfree surface shear flow is investigated both theoretically and experimentally, and the followingresults are obtained. The mean velocity distribution is good approximated by the well-known log-arithmic law, but the Karman constant and the integral constant are differ from these of pipe flow.The vertical distribution of the turbulence intensity, the Eulerian integral scale and the energydissipation rate are represented in form of universal functions, whose functional forms aredetermined experimentally.