DOI: 10.1029/2017JF004580
Scopus记录号: 2-s2.0-85051952090
论文题名: The Cessation Threshold of Nonsuspended Sediment Transport Across Aeolian and Fluvial Environments
作者: Pähtz T. ; Durán O.
刊名: Journal of Geophysical Research: Earth Surface
ISSN: 21699003
出版年: 2018
卷: 123, 期: 8 起始页码: 1638
结束页码: 1666
语种: 英语
英文关键词: bedload
; cessation threshold
; incipient motion
; intermittency
; saltation
; sediment transport
英文摘要: Using particle-scale simulations of nonsuspended sediment transport for a large range of Newtonian fluids driving transport, including air and water, we determine the bulk transport cessation threshold Θr t by extrapolating the transport load as a function of the dimensionless fluid shear stress (Shields number) Θ to the vanishing transport limit. In this limit, the simulated steady states of continuous transport can be described by simple analytical model equations relating the average transport layer properties to the law of the wall flow velocity profile. We use this model to calculate Θr t for arbitrary environments and derive a general Shields-like threshold diagram in which a Stokes-like number replaces the particle Reynolds number. Despite the simplicity of our hydrodynamic description, the predicted cessation threshold, both from the simulations and analytical model, quantitatively agrees with measurements for transport in air and viscous and turbulent liquids despite not being fitted to these measurements. We interpret the analytical model as a description of a continuous rebound motion of transported particles and thus Θr t as the minimal fluid shear stress needed to compensate the average energy loss of transported particles during an average rebound at the bed surface. This interpretation, supported by simulations near Θr t, implies that entrainment mechanisms are needed to sustain transport above Θr t. While entrainment by turbulent events sustains intermittent transport, entrainment by particle-bed impacts sustains continuous transport. Combining our interpretations with the critical energy criterion for incipient motion by Valyrakis and coworkers, we put forward a new conceptual picture of sediment transport intermittency. ©2018. The Authors. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/113463
Appears in Collections: 气候减缓与适应
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作者单位: Institute of Port, Coastal and Offshore Engineering, Ocean College, Zhejiang University, Hangzhou, China; State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Hangzhou, China; Department of Ocean Engineering, Texas A&M University, College Station, TX, United States
Recommended Citation:
Pähtz T.,Durán O.. The Cessation Threshold of Nonsuspended Sediment Transport Across Aeolian and Fluvial Environments[J]. Journal of Geophysical Research: Earth Surface,2018-01-01,123(8)