A minimal coupled fluid-discrete element model for bedload transport

Maurin, Raphaël; Chauchat, Julien; Chareyre, Bruno; Frey, Philippe

doi:10.1063/1.4935703

Cited by 52 publications

(97 citation statements)

References 54 publications

(72 reference statements)

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“…Before they came to a halt, these particles destabilized other particles resting on the bed interface, and thereby they initiated low sediment transport. Our findings are in line with recent simulations based on discrete element methods. Maurin et al [] obtained a similar particle velocity profile to the one reported in Figure a. Clark et al [] showed how important the particle Stokes number is when studying particle dynamics at the onset of motion.…”

Section: Discussionmentioning

confidence: 99%

Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

Heyman

Bohorquez

Ancey

2016

J. Geophys. Res. Earth Surf.

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International audienceIn gravel bed rivers, bed load transport exhibits considerable variability in time and space. Recently, stochastic bed load transport theories have been developed to address the mechanisms and effects of bed load transport fluctuations. Stochastic models involve parameters such as particle diffusivity, entrainment, and deposition rates. The lack of hard information on how these parameters vary with flow conditions is a clear impediment to their application to real-world scenarios. In this paper, we determined the closure equations for the above parameters from laboratory experiments. We focused on shallow supercritical flow on a sloping mobile bed in straight channels, a setting that was representative of flow conditions in mountain rivers. Experiments were run at low sediment transport rates under steady nonuniform flow conditions (i.e., the water discharge was kept constant, but bed forms developed and migrated upstream, making flow nonuniform). Using image processing, we reconstructed particle paths to deduce the particle velocity and its probability distribution, particle diffusivity, and rates of deposition and entrainment. We found that on average, particle acceleration, velocity, and deposition rate were responsive to local flow conditions, whereas entrainment rate depended strongly on local bed activity. Particle diffusivity varied linearly with the depth-averaged flow velocity. The empirical probability distribution of particle velocity was well approximated by a Gaussian distribution when all particle positions were considered together. In contrast, the particles located in close vicinity to the bed had exponentially distributed velocities. Our experimental results provide closure equations for stochastic or deterministic bed load transport models. ©2016. American Geophysical Union. All Rights Reserved

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Section: Discussionmentioning

confidence: 99%

Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

Heyman

Bohorquez

Ancey

2016

J. Geophys. Res. Earth Surf.

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“…Elle fait intervenir les forces de portance, de flottabilité et de traînée. La force de traînée a été modifiée par rapport au travail initié par MAURIN et al (2015) pour prendre en compte des nombres de Reynolds de particule plus élevés. Les modifications étant validées, les premières simulations pour le Nord Cotentin ont été réalisées afin de les appliquer in-fine aux sites EMR hydrolien.…”

Section: Discussionunclassified

Modélisation du transport particulaire pour les énergies marines renouvelables

Adong¹,

Bennis²,

Mouazé³

2016

XIVèmes Journées, Toulon

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Résumé:La transition énergétique est au coeur de l'actualité avec notamment le développement des énergies marines renouvelables. Le dimensionnement et le positionnement des engins récupérateurs d'énergie nécessitent une bonne connaissance de l'environnement hydro-sédimentaire. Les sédiments en suspension peuvent affecter le fonctionnement des machines, en particulier dans un environnement hydrodynamique extrême comme celui du Raz-Blanchard. Afin de modéliser ce transport en suspension, un modèle d'éléments discrets simulant les sédiments a été forcé par un modèle hydrodynamique côtier. Des modifications ont été apportées au modèle d'éléments discrets pour prendre en compte le caractère tridimensionnel de l'écoulement ainsi que sa nature turbulente. L'étape de validation a été réalisée avec des expériences en laboratoire décrivant la mise en mouvement d'un lit sédimentaire par un écoulement fluide. Globalement, les résultats numériques sont en accord avec les mesures tant pour les profils verticaux de la vitesse fluide que pour la fraction solide. Ensuite, les premières simulations du transport sédimentaire de cailloutis pour un site côtier du Nord Cotentin sont discutées.

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“…The model has been validated with turbulent bedload transport experiments, in terms of both the sediment transport rate and granular depth profiles. More details can be found in [7,11]. This model has also been used to analyse the dense granular rheology in turbulent bedload transport [12].…”

Section: Coupled Fluid-discrete Element Modelmentioning

confidence: 99%

“…The friction coefficient is set to 0.4, and a restitution coefficient of 0.5 is taken consistently with the experimental validation [7].…”

Section: Coupled Fluid-discrete Element Modelmentioning

confidence: 99%

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Investigation of vertical size segregation in bedload sediment transport with a coupled fluid-discrete element model

Frey¹,

Maurin²,

Morchid-Alaoui³

et al. 2017

EPJ Web Conf.

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Abstract. In order to gain understanding of kinetic sieving-type segregation in bedload sediment transport, numerical experiments of two-size particle mixtures were carried out, using a validated coupled fluiddiscrete element model developed at Irstea. A 3D 10% steep domain consisting at initial time of a given number of layers of 4 mm particles deposited on top of a coarser 6 mm particle bed, was submitted to a turbulent and supercritical fluid shear flow (Shields numbers of 0.1 and 0.3). The elevation of the centre of mass of the infiltrated fine particles is observed to follow the same logarithmic decrease with time, whatever the initial number of fine layers. This decrease is steeper for a higher Shields number. The main result is that this typical behaviour is related at first order to the shear rate depth profile.

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A minimal coupled fluid-discrete element model for bedload transport

Cited by 52 publications

References 54 publications

Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

Modélisation du transport particulaire pour les énergies marines renouvelables

Investigation of vertical size segregation in bedload sediment transport with a coupled fluid-discrete element model

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