開水路流れにおける乱れの空間構造について

Abstract

This paper deals with the spatial structure of turbulence in free surface shear flows. The fieldmeasurements of turbulence were carried out in the Nobi agricultural canal constructed at mu-yama along the left side levee of the river Kiso, using 4 current meters of a propeller-dynamo type.The intensity, the skewness factor and the flatness fator of velocity fluctuations, the auto- andcross-correlation and spectra, the coherence and the phase-lag were analyzed from the record ofvelocity fluctuations in the flow direction. From these experimental data, some qualitative pro-perties of spatial structure of turbulence were revealed, that is, the turbulence element was widerspread in the free surface region, and the phase of turbulence near the free surface was in progresscompared with that near the bed. Furetheremore, the hypothesis of frozen turbulence by G. I.Taylor was good applicated for the turbulence in the flow direction.