FLOW RESISTANCE IN MOBILE BED MEANDERING CHANNEL FOR OVERBANK FLOW

摘要

The velocity measurements were carried out in the meandering channel with mobile bed for overbank flows using Laser Doppler Anemometer (LDA). The structure of velocity distribution along the meandering channel for each overbank flow depth was obtained. The comparison of the velocity structure between the flat bed and mobile bed cases were made. The bed forms were taken using a photogrametry each overbank flow depth. The forms show interesting features along the meandering channel. There is a clear evidence of the effects of secondary flow and interfacial turbulence on the bed forms. The attempt was made to work out friction factor on mobile bed through a simple depth averaged velocity analysis. The friction factor for the flat bed case was obtained by measuring boundary shear stress and velocity. Both friction factors are compared, which shows that a large difference occurs in the shallow overbank flow depth and a little difference occurs in the deep overbank flow case.