河川における乱流エネルギー逸散率について

Abstract

The rate of dissipation of turbulent energy per unit mass & which represents one ofthe fundamental characteristics of a turbulent flow was estimated in a river flow. Estima-tions were made from the results of observations of turbulent velocity measured by theuse of the ultrasonic flowmeter and propeller-type current meter in the Uji river andthe Kitatone river. The shape of the calculated structural functions in a region of localisotropy gave a good estimate of 8.The value of S at 40cm below the surface in the Uji river (depth 2. L-'2. 7 m, meanvelocity 1. 1-1. 3 m/sec) was estimated as about 0. 3-~0. 5 cm5/sec3. Vertical distribution ofC was also estimated. The value of & of the horizontal turbulence was determined asabout 104cm2/sec3 in the Kitatone river (wi&h 240m, depth 4m, mean velocity 2Ocm/sec).The Kolmogorov universal constant of the one-dimensional energy spectrum wasestimated in a river flow by the use of the newly developed ultrasonic flowmeter basedon the method of pulse-time difference.