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Title: Entrainment of coarse grains using a discrete particle model

Conventional bedload transport models and incipient motion theories relying on a time-averaged boundary shear stress are incapable of accounting for the effects of fluctuating near-bed velocity in turbulent flow and are therefore prone to significant errors. Impulse, the product of an instantaneous force magnitude and its duration, has been recently proposed as an appropriate criterion for quantifying the effects of flow turbulence in removing coarse grains from the bed surface. Here, a discrete particle model (DPM) is used to examine the effects of impulse, representing a single idealized turbulent event, on particle entrainment. The results are classified according to the degree of grain movement into the following categories: motion prior to entrainment, initial dislodgement, and energetic displacement. The results indicate that in all three cases the degree of particle motion depends on both the force magnitude and the duration of its application and suggest that the effects of turbulence must be adequately accounted for in order to develop a more accurate method of determining incipient motion. DPM is capable of simulating the dynamics of grain entrainment and is an appropriate tool for further study of the fundamental mechanisms of sediment transport.
Authors:
 [1] ;  [2]
  1. Lecturer in Water and Environmental Engineering, Rankine 817b, University of Glasgow, Glasgow G12 8LT (United Kingdom)
  2. Environmental Engineer, Arcadis, USA (formerly: research assistant Virginia Tech, USA) (United States)
Publication Date:
OSTI Identifier:
22307957
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1618; Journal Issue: 1; Conference: ICCMSE 2014: International conference on computational methods in science and engineering 2014, Athens (Greece), 4-7 Apr 2014; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MATHEMATICAL MODELS; PARTICLES; PULSES; SHEAR; STRESSES; SURFACES; TRANSPORT THEORY; TURBULENCE; TURBULENT FLOW; VELOCITY