Polydisperse suspensions: erosion, deposition, and flow capacity

Robert Dorrell, Andrew Hogg, David Pritchard

Research output: Contribution to journalArticle

15 Citations (Scopus)
65 Downloads (Pure)

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.
Original languageEnglish
Pages (from-to)1939-1955
Number of pages17
JournalJournal of Geophysical Research: Earth Surface
Volume118
Issue number3
Early online date28 Aug 2013
DOIs
Publication statusPublished - 2013

Keywords

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

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