Diffusion of bedload particles in open-channel flows: distribution of travel times and second-order statistics of particle trajectories

Robert J. Bialik*, Vladimir I. Nikora, Mikołaj Karpiński, Paweł M. Rowiński

*Corresponding author for this work

Research output: Contribution to journalArticle

18 Citations (Scopus)
6 Downloads (Pure)

Abstract

The motion of bedload particles is diffusive and occurs within at least three scale ranges: local, intermediate and global, each of which with a distinctly different diffusion regime. However, these regimes, extensions of the scale ranges and boundaries between them remain to be better defined and quantified. These issues are explored using a Lagrangian model of saltating grains over the uniform fixed bed. The model combines deterministic particle motion dynamics with stochastic characteristics such as probability distributions of step lengths and resting times. Specifically, it is proposed that a memoryless exponential distribution is an appropriate model for the distribution of rest periods while the probability that a particle stops after a current jump follows a binomial distribution, which is a distribution with lack of memory as well. These distributions are incorporated in the deterministic Lagrangian model of saltating grains and extensive numerical simulations are conducted for the identification of the diffusive behavior of particles at different time scales. Based on the simulations and physical considerations, the local, intermediate, and global scale ranges are quantified and the transitions from one range to another are studied for a spectrum of motion parameters. The obtained results demonstrate that two different time scales should be considered for parameterization of diffusive behavior within intermediate and global scale ranges and for defining the local–intermediate and intermediate–global boundaries. The simulations highlight the importance of the distributions of the step lengths and resting times for the identification of the boundaries (or transition intervals) between the scale ranges.

Original languageEnglish
Pages (from-to)1281-1292
Number of pages12
JournalEnvironmental Fluid Mechanics
Volume15
Issue number6
Early online date2 Jun 2015
DOIs
Publication statusPublished - Dec 2015

Fingerprint

Open channel flow
open channel flow
Travel time
bedload
travel time
trajectory
Trajectories
Statistics
Parameterization
Probability distributions
timescale
simulation
particle motion
Data storage equipment
statistics
distribution
particle
Computer simulation
parameterization

Keywords

  • Lagrangian model
  • Particle diffusion
  • Saltation
  • Sediment transport

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology

Cite this

Diffusion of bedload particles in open-channel flows : distribution of travel times and second-order statistics of particle trajectories. / Bialik, Robert J.; Nikora, Vladimir I.; Karpiński, Mikołaj; Rowiński, Paweł M.

In: Environmental Fluid Mechanics, Vol. 15, No. 6, 12.2015, p. 1281-1292.

Research output: Contribution to journalArticle

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