開水路流れにおける乱れの空間構造について(2) ―平均流による乱れの移流過程―

Abstract

This paper describes an experimental investigation of the spatial structure of turbulence ina free surface shear flow, carried out at the Nobi agricultural canal, using 4 current meters of apropeller-dynamo type. A convective process of turbulence is investigated through a techniqueof the space-time correlation, with and without frequency filtering, for the longitudinal componentof the velocity fluctuation.The experimental results are as follows. 1) Different turbulent spectral components of anopen channel flow are convected with different velocity, that is, the large scale disturbances nearthe free surface are convected more slowly than the small scale ones. 2) The departure of the fro-zen pattern in the period of the disturbance is remarkable for the disturbance of long period, but, in the same distance, it is remarkable for the disturbance of short period.