Incorporating the Memory Effect of Turbulence Structures Into Suspended Sediment Transport Modeling
Journal
Water Resources Research
Journal Volume
57
Journal Issue
3
Date Issued
2021
Author(s)
Abstract
Modeling of the random movement of fine sediment particles in open-channel turbulent flow is mostly built upon the memoryless Brownian motion process. Such a process describes the chaotic behavior of small particles without considering temporal correlations in terms of the particle moving velocity and direction (i.e., memory). However, when particles are transported in time-persistent turbulent flow, the movements of the suspended particles may exhibit persistency that depends on the various temporal durations of turbulent flow structures—such persistence results in direction and magnitude variations in the velocity of the fine moving particles. The diffusion property of the particles may then deviate from normal diffusion. The conventional memoryless random walk models may not provide a comprehensive description of the particle diffusion process for the duration of turbulence structures when the particles are subject to memory effects. In this study, a novel random walk model is proposed to present the temporal correlation of the suspended sediment particle velocity caused by turbulence structures in open channel flow. The probabilistic properties of the proposed model are discussed. In particular, enhanced physical insights are obtained regarding the particle diffusion behavior in turbulent flows. Numerical simulations are conducted to demonstrate that, similar to the conventional memoryless random walk models, the proposed model shows normal diffusion for long-term observations, despite its local superdiffusion behavior. The effective diffusion coefficient of the proposed stochastic process on a long-term time scale is formulated. ? 2021. American Geophysical Union. All Rights Reserved.
Subjects
anomalous diffusion
non-Markovian process
random-walk based model
stochastic sediment transport
suspended sediment transport model
temporal correlation
Brownian movement
Diffusion in solids
Open channel flow
Sediment transport
Stochastic systems
Suspended sediments
Turbulence
Turbulent flow
Velocity control
Brownian motion process
Effective diffusion coefficients
Long term observations
Particle diffusion process
Probabilistic properties
Random walk modeling
Temporal correlations
Turbulence structures
Elementary particle sources
Brownian motion
modeling
open channel flow
persistence
sediment transport
stochasticity
suspended sediment
turbulence
turbulent flow
Type
journal article