On aeolian transport: Grain-scale interactions, dynamical mechanisms and scaling laws

Durán, Orencio; Claudin, Philippe; Andreotti, Bruno

doi:10.1016/j.aeolia.2011.07.006

Cited by 263 publications

(418 citation statements)

References 115 publications

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“…In this regime, the approximation K ≈ 1 is not valid anymore, instead the feedback term K follows Eq. (62). Consequently, L s is proportional to V Aeolian regime under Martian conditions -For aeolian transport under Martian conditions, L s /(sd) shows a qualitative behavior with d that is different from the one of aeolian transport under terrestrial conditions.…”

Section: Dependence Of the Saturation Length On Particle Size Andmentioning

confidence: 99%

Analytical model for flux saturation in sediment transport

et al. 2014

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The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment and for a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sediment is controlled by situations out-of-equilibrium. In particular, it is controlled by the saturation length characterizing the distance it takes for the particle flux to reach a new equilibrium after a change in flow conditions. The saturation of mass density of particles entrained into transport and the relaxation of particle and fluid velocities constitute the main relevant relaxation mechanisms leading to saturation of the sediment flux. Here we present a theoretical model for sediment transport which, for the first time, accounts for both these relaxation mechanisms and for the different types of sediment entrainment prevailing under different environmental conditions. Our analytical treatment allows us to derive a closed expression for the saturation length of sediment flux, which is general and can thus be applied under different physical conditions.

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Section: Dependence Of the Saturation Length On Particle Size Andmentioning

confidence: 99%

Analytical model for flux saturation in sediment transport

et al. 2014

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“…This regime, called saltation, is the primary mode of transport in Aeolian sand transport, and has been investigated theoretically (Bagnold 1941, Bagnold 1966, Owen 1964, Ungar & Haff 1987, Sauermann et al 2001, Andreotti 2004, Jenkins et al 2010, experimentally (Bagnold 1941, Nalpanis et al 1993, Foucaut & Stanislas 1997, Iversen & Rasmussen 1999, Ho et al 2014) and numerically (Anderson & Haff 1988, Kok & Renno 2009). More references can be found in recent reviews on Aeolian transport (Durán et al 2011, Kok et al 2012, Valance et al 2015. Saltation may also be relevant in aquatic flows (Fernandez Luque & van Beek 1976, Abbot & Francis 1977, Ancey et al 2002, Niño & García 1998.…”

Section: Introductionmentioning

confidence: 99%

Periodic saltation over hydrodynamically rough beds: aeolian to aquatic

2015

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We determine approximate, analytical solutions for average, periodic trajectories of particles that are accelerated by the turbulent shearing of a fluid between collisions with a hydrodynamically rough bed. We indicate how the viscosity of the fluid may influence the collisions with the bed. The approximate solutions compare well with periodic solutions for average periodic trajectories over rigid-bumpy and erodible beds that are generated numerically. The analytic solutions permit the determination of the relations between the particle flux and the strength of the shearing flow over a range of particle and fluid properties that vary between those for sand in air and sand in water.

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“…If we consider a situation where we have a sudden increase or decrease in wind velocity, the mass flow rate does not adapt instantaneously to its new equilibrium value. This transient lasts a certain characteristic time (or occurs over a certain characteristic distance) for the new grains extracted from the bed to reach the air velocity and for the particle concentration to relax toward its new equilibrium value [Durán et al, 2011;Valance et al, 2015]. During this transient process, the air speed within the transport layer has also to decrease to its equilibrium value because of the negative feedback of transport on the wind.…”

Section: Introductionmentioning

confidence: 99%

“…This equilibrium state is characterized by an equilibrium or saturated mass flux which is an increasing function of the wind strength. Up to now, most researches were focused on the description of the equilibrium state of transport where erosion and deposition processes balance exactly [Bagnold , 1941;Shao, 2008;Durán et al, 2011;Kok et al, 2012]. A further interesting and important issue is the description of the out-ofequilibrium transport.…”

Section: Introductionmentioning

confidence: 99%

Aeolian Sand Transport in Out‐of‐Equilibrium Regimes

Selmani

Valance

Moctar

et al. 2018

Geophysical Research Letters

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We investigate the relaxation process toward the equilibrium regime of saltation transport in the context of nonuniform conditions. Relaxation phenomena can be described in terms of a characteristic length scale that measures the distance for the particle flux to adapt to a spatial change in flow or boundary conditions. We conducted wind tunnel experiments to document the influence of the upwind mass flux on the relaxation process. For zero upwind mass flux conditions, the relaxation process is monotone and the relaxation length is independent of the wind strength. In contrast, for nonzero upwind flux conditions (obtained by releasing particles in the flow from a finite height), the relaxation process is nonmonotone and is well captured by damped harmonic oscillations. Importantly, the relaxation length increases with increasing air flow velocity but is almost insensitive to the magnitude of the upwind flux. Our experimental outcomes clearly indicate that the relaxation of far from equilibrium transport regimes strongly deviates from a simple exponential behavior.

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On aeolian transport: Grain-scale interactions, dynamical mechanisms and scaling laws

Cited by 263 publications

References 115 publications

Analytical model for flux saturation in sediment transport

Analytical model for flux saturation in sediment transport

Periodic saltation over hydrodynamically rough beds: aeolian to aquatic

Aeolian Sand Transport in Out‐of‐Equilibrium Regimes

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