Polydisperse suspensions: erosion, deposition, and flow capacity

Robert Dorrell, Andrew Hogg, David Pritchard

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Deposition from particle-laden flows is often described in terms of the capacity and competence of the flow, but robust definitions of these terms have proved elusive. In this paper we provide a mathematical modelling framework within which erosion and deposition of polydisperse sediment, and thus flow capacity and competence, can be rigorously defined. This framework explicitly captures the coupling between the suspension and an active layer of sediment at the top of the bed, and is capable of describing both depositional and erosional flows over both erodible and non-erodible beds. Crucially, the capacity of a flow is shown to depend on the erosional and depositional history because these processes determine the composition of the active layer. This dependence is explored within models of bidisperse and polydisperse suspensions. It is further demonstrated that monodisperse representations of suspended sediment transport may severely underpredict actual flow capacity. The polydisperse model is validated against recent experimental studies of the evolution of suspended material in waning turbulent flows, and is used to demonstrate that loss of capacity is the principal driver of sediment deposition.
LanguageEnglish
Pages1939-1955
Number of pages17
JournalJournal of Geophysical Research: Earth Surface
Volume118
Issue number3
Early online date28 Aug 2013
DOIs
Publication statusPublished - 2013

Fingerprint

Erosion
erosion
Sediments
Sediment
Suspended sediments
sediments
active layer
Sediment transport
Turbulent flow
beds
sediment
Sediment Transport
sediment transport
Chemical analysis
turbulent flow
Turbulent Flow
Mathematical Modeling
suspended sediment
Driver
Experimental Study

Keywords

  • erosion
  • particle-laden flows
  • suspended sediment transport
  • deposition
  • polydisperse suspensions
  • polydisperse models

Cite this

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Polydisperse suspensions : erosion, deposition, and flow capacity. / Dorrell, Robert; Hogg, Andrew; Pritchard, David.

In: Journal of Geophysical Research: Earth Surface, Vol. 118, No. 3, 2013, p. 1939-1955.

Research output: Contribution to journalArticle

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T2 - Journal of Geophysical Research: Earth Surface

AU - Dorrell, Robert

AU - Hogg, Andrew

AU - Pritchard, David

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AB - Deposition from particle-laden flows is often described in terms of the capacity and competence of the flow, but robust definitions of these terms have proved elusive. In this paper we provide a mathematical modelling framework within which erosion and deposition of polydisperse sediment, and thus flow capacity and competence, can be rigorously defined. This framework explicitly captures the coupling between the suspension and an active layer of sediment at the top of the bed, and is capable of describing both depositional and erosional flows over both erodible and non-erodible beds. Crucially, the capacity of a flow is shown to depend on the erosional and depositional history because these processes determine the composition of the active layer. This dependence is explored within models of bidisperse and polydisperse suspensions. It is further demonstrated that monodisperse representations of suspended sediment transport may severely underpredict actual flow capacity. The polydisperse model is validated against recent experimental studies of the evolution of suspended material in waning turbulent flows, and is used to demonstrate that loss of capacity is the principal driver of sediment deposition.

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