TURBULENT STRUCTURE IN OPEN-CHANNEL FLOW OVER FLAT BED WITH BED-LOAD TRANSPORT

Abstract

In open channel fows with bed-load transport, mean flow properties, turbulence intensities and Reynolds stress profiles are affected by the bed-load motions. In this study, LDA measurements over flat movable sand bed were conducted with high accuracy. The sediment transport was also measured simultaneously. It was found that the mean velocity gradient near the bed decreases with an increase of the bedload transport rate. Both the horizontal and vertical turbulence intensities, also increase in the inner layer as compared with those of rough fixed-bed open channel flows. Reynolds stress profiles near the bed deviate systematically from the triangular distribution which is theoretically valid in a two dimensional uniform open channel flow.