Turbulent Flow over a Gravel River Bed

Abstract

Observations of turbulence are made in the Chikuma river and in the Sai river with 3 electro-magnetic flowmeters. Representative scales of the river bed gravels at the observation points are the values from about 10cm to 20cm.The observation data shows the fact that ∩-shapet voltex tubes contribute to Reynolds-stress positively and quickly. The results of the observations are as follows.1) The values of Reynolds-stress decrease with hight. Some of the observation data show that the distribution pattern has turnning point of a curve near a river bed.2) The values of the energy dissipation decrease almost uniformly with hight. The maximum value obtained from the observation is 14.5 cm2/sec3.3) The scales of energy containing eddies increase with hight. When Z/H eqals to 0.8, it takes the value of about 10H. But some cases show that it dose not exceed 5H through the whole depth.