Sediment Transport under Sheet-Flow Conditions

A series of laboratory experiments in an oscillatory tank was carried out to investigate the sheet flow of sediment. Objectives of the study were to determine the criterion for inception of sheet flow, and to evaluate the sediment transport rate under the sheet flow condition. In order to proceed with the investigation, it was necessary to develop devices appropriate for tracing the sediment particle movement, and for measuring the extremely dense sediment concentration in the moving layer of sheet flow. The chief results are: 1) the criteria for the inception of sheet flow given by Manohar C1955) and by Komar and Miller (1974) are both applicable to materials composed of spheroidal particles, and 2) the average rate of sediment transport for sheet flow is well described by an empirical relationship given by Madsen and Grant (1976) for the bed load transport rate on a plane bed in oscillatory flow.

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A simple model of unsteady sheet-flow sediment transport

Coastal Engineering ◽

10.1016/s0378-3839(03)00025-5 ◽

2003 ◽

Vol 48 (3) ◽

pp. 171-188 ◽

Cited By ~ 23

Author(s):

J Malarkey ◽

A.G Davies ◽

Z Li

Keyword(s):

Sediment Transport ◽

Simple Model ◽

Sheet Flow

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Sediment suspension under sheet flow conditions beneath random waves plus current

Continental Shelf Research ◽

10.1016/j.csr.2004.06.021 ◽

2004 ◽

Vol 24 (17) ◽

pp. 2065-2091 ◽

Cited By ~ 16

Author(s):

Lars Erik Holmedal ◽

Dag Myrhaug ◽

Karl J. Eidsvik

Keyword(s):

Sediment Suspension ◽

Random Waves ◽

Flow Conditions ◽

Sheet Flow

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LAG EFFECTS IN MORPHODYNAMIC MODELLING OF ENGINEERING IMPACTS

Coastal Engineering Proceedings ◽

10.9753/icce.v33.sediment.45 ◽

2012 ◽

Vol 1 (33) ◽

pp. 45 ◽

Cited By ~ 1

Author(s):

Michiel A.F. Knaapen ◽

David M. Kelly

Keyword(s):

Sediment Transport ◽

Sediment Concentration ◽

Flow Conditions ◽

Flume Experiments ◽

Lag Effects ◽

Morphodynamic Modelling ◽

Morphology Model ◽

Bed Exchange ◽

Morphodynamic Modeling ◽

Concentration Equation

This paper details the extension of the sediment transport and morphology model SISYPHE to include a lag term within the bed exchange source term of the, depth-averaged, continuity of sediment concentration equation. This lag term represents the time it takes for a sediment concentration profile to adapt to spatial or temporal changes in the flow. The inclusion of a lag term means that the settling velocity is no longer the only scaling factor for the exchange of sediment between the water and the bed. The modified sediment transport and morphodynamics model is tested against field data from the Thames estuary (UK) and on the morphodynamic development of a dredged trench in flume experiments. It is illustrated that the lag factor introduced is essential to model the sediment transport and morphodynamics, especially when considering engineered situations, where the bed is out of equilibrium with the flow conditions. Moreover, with this lag factor included, there is evidence that SISYPHE can be used for morphodynamic modeling of engineered situations.

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