Investigation of Saltating Particle Motions

Lee, Hong‐Yuan; Hsu, In-Song

doi:10.1061/(asce)0733-9429(1994)120:7(831)

Cited by 156 publications

(163 citation statements)

References 14 publications

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“…Spin lift has been investigated by , , and Lee and Hsu [1994], who showed that it has a small but perceptible effect on the length and height of saltation trajectories. Form lift due to asymmetry in particle shape remains largely unstudied.…”

Section: A3 Liftmentioning

confidence: 99%

Forces on stationary particles in near‐bed turbulent flows

Schmeeckle¹,

Nelson²,

Shreve³

2007

J. Geophys. Res.

204

272

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[1] In natural flows, bed sediment particles are entrained and moved by the fluctuating forces, such as lift and drag, exerted by the overlying flow on the particles. To develop a better understanding of these forces and the relation of the forces to the local flow, the downstream and vertical components of force on near-bed fixed particles and of fluid velocity above or in front of them were measured synchronously at turbulence-resolving frequencies (200 or 500 Hz) in a laboratory flume. Measurements were made for a spherical test particle fixed at various heights above a smooth bed, above a smooth bed downstream of a downstream-facing step, and in a gravel bed of similarly sized particles as well as for a cubical test particle and 7 natural particles above a smooth bed. Horizontal force was well correlated with downstream velocity and not correlated with vertical velocity or vertical momentum flux. The standard drag formula worked well to predict the horizontal force, but the required value of the drag coefficient was significantly higher than generally used to model bed load motion. For the spheres, cubes, and natural particles, average drag coefficients were found to be 0.76, 1.36, and 0.91, respectively. For comparison, the drag coefficient for a sphere settling in still water at similar particle Reynolds numbers is only about 0.4. The variability of the horizontal force relative to its mean was strongly increased by the presence of the step and the gravel bed. Peak deviations were about 30% of the mean force for the sphere over the smooth bed, about twice the mean with the step, and 4 times it for the sphere protruding roughly half its diameter above the gravel bed. Vertical force correlated poorly with downstream velocity, vertical velocity, and vertical momentum flux whether measured over or ahead of the test particle. Typical formulas for shear-induced lift based on Bernoulli's principle poorly predict the vertical forces on near-bed particles. The measurements suggest that particlescale pressure variations associated with turbulence are significant in the particle momentum balance.

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Section: A3 Liftmentioning

confidence: 99%

Forces on stationary particles in near‐bed turbulent flows

Schmeeckle¹,

Nelson²,

Shreve³

2007

J. Geophys. Res.

204

272

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“…Moreover, the time between pickup and deposition is also stored and averaged. Knowing the duration of the saltation event, T s , the associated mean streamwise particle velocity U s is obtained as Niño et al [1994], Abbott and Francis [1977], and Lee and Hsu [1994]. Similarly, results for the dimensionless streamwise saltation velocity, obtained from the present numerical results, are plotted in Figure 14c as a function of the ration Ã = Ã cr , together with those corresponding to gravel saltation [Niño et al, 1994]; the experimental results of Francis [1973], Fernandez-Luque and van Beek [1976], and Lee and Hsu [1994]; and the theoretical relation of Ashida and Michiue [1972].…”

Section: Sediment Saltationmentioning

confidence: 99%

Detailed simulation of morphodynamics: 2. Sediment pickup, transport, and deposition

Nabi

Vriend

Mosselman

et al. 2013

Water Resources Research

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[1] The paper describes a numerical model for simulating sediment transport with eddyresolving 3-D models. This sediment model consists of four submodels: pickup, transport over the bed, transport in the water column and deposition, all based on a turbulent flow model using large-eddy simulation. The sediment is considered as uniform rigid spherical particles. This is usually a valid assumption for sand-bed rivers where underwater dune formation is most prominent. Under certain shear stress conditions, these particles are picked up from the bed due to an imbalance of gravity and flow forces. They either roll and slide on the bed in a sheet of sediment or separate from the bed and get suspended in the flow. Sooner or later, the suspended particles settle on the bed again. Each of these steps is modeled separately, yielding a physics-based process model for sediment transport, suitable for the simulation of bed morphodynamics. The sediment model is validated with theoretical findings such as the Rouse profile as well as with empirical relations of sediment bed load and suspended load transport. The current model shows good agreement with these theoretical and empirical relations. Moreover, the saltation mechanism is simulated, and the average saltation length, height, and velocity are found to be in good agreement with experimental results.

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“…It should be noted, however, that they established a basis for the construction of later models. However, only the dynamic development of and open access to computers in the 1980s and 1990s allowed for the first significant step in the understanding of saltation through the possibility of carrying out simulations based on theoretical and numerical models Smith 1985, 1989;Sekine and Kikkawa 1992;Lee and Hsu 1994;Niño andGarcia 1994, 1998b;Rowiński 1995). Note that only models on saltation in flowing water are considered here.…”

Section: Introductionmentioning

confidence: 99%

Lagrangian Modelling of Saltating Sediment Transport: A Review

Bialik

2015

GeoPlanet: Earth and Planetary Sciences

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One hundred years of research on the saltation in rivers, both experimental and numerical, has allowed for a fairly good improvement of our knowledge of the physics of the saltation process. Lagrangian modelling has played a huge role in this field and has made it possible to apply the knowledge obtained in the analysis of processes associated with the movement of sediment particles. The present paper briefly reviews the current state-of-the-art of the Lagrangian modelling of saltating grains in open channels and highlights recent findings in three areas in which employment of the Lagrangian models of saltation improve our understanding of sediment transport in rivers, namely: initial motion of saltating grains, diffusion of particles and calculation of the bedload transport rate. The particular challenges in all of these research areas are discussed and future ways forward are presented.

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Investigation of Saltating Particle Motions

Cited by 156 publications

References 14 publications

Forces on stationary particles in near‐bed turbulent flows

Forces on stationary particles in near‐bed turbulent flows

Detailed simulation of morphodynamics: 2. Sediment pickup, transport, and deposition

Lagrangian Modelling of Saltating Sediment Transport: A Review

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