Equilibrium Near-Bed Concentration of Suspended Sediment
- 1 December 1999
- journal article
- Published by American Society of Civil Engineers (ASCE) in Journal of Hydraulic Engineering
- Vol. 125 (12), 1270-1278
- https://doi.org/10.1061/(asce)0733-9429(1999)125:12(1270)
Abstract
A new approach is presented for calculating the equilibrium near-bed concentration of suspended sediment in an alluvial channel flow. It is formulated from the balance between bed sediment entrainment and suspended sediment deposition across the near-bed boundary. The entrainment flux is determined making use of a turbulent bursting outer-scale-based function and the flux of deposition by the product of near-bed concentration and hindered settling velocity of sediment. A number of flume data records in the literature are analyzed to calibrate and verify the present approach. The observed near-bed concentrations for the data records are obtained by first isolating the suspended load transport rate from the observed total load transport rate using Engelund and Fredsoe's bed-load formula and then equating the suspended load transport rate to the shape integration of Dyer and Soulsby. The present approach is shown to perform satisfactorily compared to the results of data analysis. It is found that the near-bed concentration is evidently dependent on sediment particle size in addition to the Shields parameter due to skin friction. This finding seems to challenge previous relationships that simply represent the near-bed concentration as empirical functions of the purely skin-friction-related Shields parameter.Keywords
This publication has 23 references indexed in Scilit:
- EFFECT OF BED LOAD MOTION ON BURSTING PHENOMENA IN OPEN CHANNEL FLOWSDoboku Gakkai Ronbunshu, 1999
- Turbulence Modulation and Particle Velocities over Flat Sand Beds at Low Transport RatesJournal of Hydraulic Engineering, 1997
- Turbulent Bursting-Based Sediment Entrainment FunctionJournal of Hydraulic Engineering, 1997
- Data Analysis of Bed Concentration of Suspended SedimentJournal of Hydraulic Engineering, 1994
- Measurements of Turbulence and Suspended Sediment in Tidal RiverJournal of Hydraulic Engineering, 1993
- Coherent Motions in the Turbulent Boundary LayerAnnual Review of Fluid Mechanics, 1991
- Sand Transport on the Continental ShelfAnnual Review of Fluid Mechanics, 1988
- Particle motions near the bottom in turbulent flow in an open channel. Part 2Journal of Fluid Mechanics, 1981
- Particle motions near the bottom in turbulent flow in an open channelJournal of Fluid Mechanics, 1978
- Sedimentological and fluid-dynamic implications of the turbulent bursting phenomenon in geophysical flowsJournal of Fluid Mechanics, 1976