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112 results on '"Devauchelle, Olivier"'

1. Walkers in a wave field with memory

Author

Devauchelle, Olivier, Lajeunesse, Éric, James, François, Josserand, Christophe, and Lagrée, Pierre-Yves

Subjects
Walking droplets, Wave-particle interaction, Faraday waves, Non-linear dynamics, Helmholtz equation, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

Couder et al. [] discovered that the behavior of droplets bouncing on a vibrated bath mimics a variety of quantum phenomena, through their coupling with a Faraday wave. Here, we introduce a continuous model inspired from this experiment, which encapsulates its essential features into a system of three simple differential equations. We show, numerically and analytically, the existence of self-propelled walkers in this framework. Finally, making use of the model’s familiar formulation, we suggest that a particle coupled with a propagating wave, instead of a standing one, behaves much like a bouncing droplet.

Published
2020
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2. Dislike of general opinion makes for tight elections

Author

Devauchelle, Olivier, Szymczak, Piotr, and Nowakowski, Piotr

Subjects
Condensed Matter - Statistical Mechanics, Physics - Physics and Society
Abstract

In modern democracies, the outcome of elections and referendums is often remarkably tight. The repetition of these divisive events are the hallmark of a split society; to the physicist, however, it is an astonishing feat for such large collections of diverse individuals. Many sociophysics models reproduce the emergence of collective human behavior with interacting agents, which respond to their environment according to simple rules, modulated by random fluctuations. A paragon of this class is the Ising model which, when interactions are strong, predicts that order can emerge from a chaotic initial state. In contrast with many elections, however, this model favors a strong majority. Here, we introduce a new element to this classical theory, which accounts for the influence of opinion polls on the electorate. This brings about a new phase in which two groups divide the opinion equally. These political camps are spatially segregated, and the sharp boundary that separates them makes the system size-dependent, even in the limit of a large electorate. Election data show that, over the last 30 years, countries with more than about a million voters often found themselves in this state, whereas elections in smaller countries yielded more consensual results. We suggest that this transition hinges on the electorate's awareness of the general opinion.

Published
2024

3. Soft matter physics of the ground beneath our feet

Author

Voigtländer, Anne, Houssais, Morgane, Bacik, Karol A., Bourg, Ian C., Burton, Justin C., Daniels, Karen E., Datta, Sujit S., Del Gado, Emanuela, Deshpande, Nakul S., Devauchelle, Olivier, Ferdowsi, Behrooz, Glade, Rachel, Goehring, Lucas, Hewitt, Ian J., Jerolmack, Douglas, Juanes, Ruben, Kudrolli, Arshad, Lai, Ching-Yao, Li, Wei, Masteller, Claire, Nissanka, Kavinda, Rubin, Allan M., Stone, Howard A., Suckale, Jenny, Vriend, Nathalie M., Wettlaufer, John S., and Yang, Judy Q.

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Geophysics
Abstract

Inspired by presentations by the authors during a workshop organized at the Princeton Center for Theoretical Science (PCTS) in January 2022, we present a perspective on some of the outstanding questions related to the "physics of the ground beneath our feet." These identified challenges are intrinsically shared with the field of Soft Matter but also have unique aspects when the natural environment is studied., Comment: Perspective Paper, 30 pages, 15 figures

Published
2023

4. Sediment load determines the shape of rivers

Author

Popović, Predrag, Devauchelle, Olivier, Abramian, Anaïs, and Lajeunesse, Eric

Subjects
Physics - Fluid Dynamics, Nonlinear Sciences - Adaptation and Self-Organizing Systems, Physics - Geophysics
Abstract

Understanding how rivers adjust to the sediment load they carry is critical to predicting the evolution of landscapes. Presently, however, no physically based model reliably captures the dependence of basic river properties, such as its shape or slope, on the discharge of sediment, even in the simple case of laboratory rivers. Here, we show how the balance between fluid stress and gravity acting on the sediment grains, along with cross-stream diffusion of sediment, determines the shape and sediment flux profile of laminar laboratory rivers which carry sediment as bedload. Using this model, which reliably reproduces the experiments without any tuning, we confirm the hypothesis, originally proposed by Parker (1978), that rivers are restricted to exist close to the threshold of sediment motion (within about 20%). This limit is set by the fluid-sediment interaction and is independent of the water and sediment load carried by the river. Thus, as the total sediment discharge increases, the intensity of sediment flux (sediment discharge per unit width) in a river saturates, and the river can only transport more sediment by widening. In this large discharge regime, the cross-stream diffusion of momentum in the flow permits sediment transport. Conversely, in the weak transport regime, the transported sediment concentrates around the river center without significantly altering the river shape. If this theory holds for natural rivers, the aspect ratio of a river could become a proxy for sediment discharge - a quantity notoriously difficult to measure in the field.

Published
2022
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7. Soft matter physics of the ground beneath our feet.

Author

Voigtländer, Anne, Houssais, Morgane, Bacik, Karol A., Bourg, Ian C., Burton, Justin C., Daniels, Karen E., Datta, Sujit S., Del Gado, Emanuela, Deshpande, Nakul S., Devauchelle, Olivier, Ferdowsi, Behrooz, Glade, Rachel, Goehring, Lucas, Hewitt, Ian J., Jerolmack, Douglas, Juanes, Ruben, Kudrolli, Arshad, Ching-Yao Lai, Wei Li, and Masteller, Claire

Published
2024
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8. Where do rivers grow? Path selection and growth in a harmonic field

Author

Cohen, Yossi, Devauchelle, Olivier, Seybold, Hansjorg F., Yi, Robert S., Szymczak, Piotr, and Rothman, Daniel H.

Subjects
Physics - Geophysics, Condensed Matter - Soft Condensed Matter, Nonlinear Sciences - Pattern Formation and Solitons
Abstract

River networks exhibit a complex ramified structure that has inspired decades of studies. Yet, an understanding of the propagation of a single stream remains elusive. Here we invoke a criterion for path selection from fracture mechanics and apply it to the growth of streams in a diffusion field. We show that a stream will follow local symmetry in order to maximize the water flux and that its trajectory is defined by the local field in its vicinity. We also study the growth of a real network. We use this principle to construct the history of a network and to find a growth law associated with it. The results show that the deterministic growth of a single channel based on its local environment can be used to characterize the structure of river networks.

Published
2014

9. Shape and dynamics of seepage erosion in a horizontal granular bed

Author

Berhanu, Michael, Petroff, Alexander, Devauchelle, Olivier, Kudrolli, Arshad, and Rothman, Daniel H.

Subjects
Physics - Fluid Dynamics, Physics - Geophysics, 76S05
Abstract

We investigate erosion patterns observed in a horizontal granular bed resulting from seepage of water motivated by observation of beach rills and channel growth in larger scale landforms. Our experimental apparatus consists of a wide rectangular box filled with glass beads with a narrow opening in one of the side walls from which eroded grains can exit. Quantitative data on the shape of the pattern and erosion dynamics are obtained with a laser-aided topography technique. We show that the spatial distribution of the source of groundwater can significantly impact the shape of observed patterns. An elongated channel is observed to grow upstream when groundwater is injected at a boundary adjacent to a reservoir held at constant height. An amphitheater (semi-circular) shape is observed when uniform rainfall infiltrates the granular bed to maintain a water table. Bifurcations are observed as the channels grow in response to the ground water. We further find that the channels grow by discrete avalanches as the height of the granular bed is increased above the capillary rise, causing the deeper channels to have rougher fronts. The spatio-temporal distribution of avalanches increase with bed height when partial saturation of the bed leads to cohesion between grains. However, the overall shape of the channels is observed to remain unaffected indicating that seepage erosion is robust to perturbation of the erosion front., Comment: 10 pages, 9 figures

Published
2012
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10. Geometry of Valley Growth

Author

Petroff, Alexander P., Devauchelle, Olivier, Abrams, Daniel M., Lobkovsky, Alexander E., Kudrolli, Arshad, and Rothman, Daniel H.

Subjects
Physics - Fluid Dynamics
Abstract

Although amphitheater-shaped valley heads can be cut by groundwater flows emerging from springs, recent geological evidence suggests that other processes may also produce similar features, thus confounding the interpretations of such valley heads on Earth and Mars. To better understand the origin of this topographic form we combine field observations, laboratory experiments, analysis of a high-resolution topographic map, and mathematical theory to quantitatively characterize a class of physical phenomena that produce amphitheater-shaped heads. The resulting geometric growth equation accurately predicts the shape of decimeter-wide channels in laboratory experiments, 100-meter wide valleys in Florida and Idaho, and kilometer wide valleys on Mars. We find that whenever the processes shaping a landscape favor the growth of sharply protruding features, channels develop amphitheater-shaped heads with an aspect ratio of pi.

Published
2010
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11. Momentum transfer across an open-channel, turbulent flow.

Author

Popović, Predrag, Devauchelle, Olivier, and Lajeunesse, Eric

Subjects
TURBULENCE, TURBULENT flow, RHEOLOGY, DIMENSIONAL analysis, ORDINARY differential equations, MOMENTUM transfer
Abstract

The distribution of stress generated by a turbulent flow matters for many natural phenomena, of which rivers are a prime example. Here, we use dimensional analysis to derive a linear, second-order ordinary differential equation for the distribution of stress across a straight, open channel, with an arbitrary cross-sectional shape. We show that this equation is a generic first-order correction to the shallow-water theory in a channel of large aspect ratio. It has two adjustable parameters - the dimensionless diffusion parameter, 1, and a local-shape parameter, a. By assuming that the momentum is carried across the stream primarily by eddies and recirculation cells with a size comparable to the flow depth, we estimate to be of the order of the inverse square root of the friction coefficient, 1~ C-1/2 f, and predict that a vanishes when the flow is highly turbulent. We examine the properties of this equation in detail and confirm its applicability by comparing it with flume experiments and field measurements from the literature. This theory can be a basis for finding the equilibrium shape of turbulent rivers that carry sediment. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Forced dewetting on porous media

Author

Devauchelle, Olivier, Josserand, Christophe, and Zaleski, Stephane

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

We study the dewetting of a porous plate withdrawn from a bath of fluid. The microscopic contact angle is fixed to zero and the flow is assumed to be parallel to the plate (lubrication approximation). The ordinary differential equation involving the position of the water surface is analysed in phase space by means of numerical integration. We show the existence of a critical value of the capillary number $\eta U / \gamma$, above which no stationary contact line can exist. An analytical model, based on asymptotic matching is developed, that reproduces the dependence of the critical capillary number on the angle of the plate with respect to the horizontal for large control parameters (3/2 power law).

Published
2005

17. Gunwale bobbing

Author

Benham, Graham P., primary, Devauchelle, Olivier, additional, Morris, Stephen W., additional, and Neufeld, Jerome A., additional

Published
2022
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29. Bedload transport in Vieux-Habitant River (Guadeloupe France)

Author

Robert, V., Allemand, P., Delacourt, Christophe, Dessert, Celine, Devauchelle, Olivier, Grandjean, Ph., Lajeunesse, E., Kitou, Thierry, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract

International audience; The physics of bedload transport has been investigated in artificial rivers, in natural rivers and by numerical simulations. These approaches demonstrated that bedload transport depends on diameter of pebbles and of the shear stress that acts on the river bed above a threshold stress. These parameters are difficult to estimate in natural rivers where the granulometry is spread out several tenths of centimeters and where the basal shear stress is very difficult to estimate. Three hundred meters of the alluvial portion of the Vieux Habitants River (Guadeloupe Island, French Antilles) have been imaged by drone once a year during 7 years. The hydrograph of the river was measured upstream at 2 km of the study area. An ortho-image at a resolution around 3 cm was computed from the images of each mission. The cobbles that were deposited or transported away between two acquisitions were mapped in a GIS. The volumetric density of deposited cobbles by classes of 10 cm for a diameter of 0.1 to 1m was reported against the maximum water flow of the river that occurred between two acquisitions. This volumetric density reflects the flow of transported cobble during the flood. The dataset shows that the volumetric density of deposited cobbles is very low when water flow is lower than 35m3/s. Above this value, the volumetric density of deposited pebble increases linearly with the flow. During the years of study, the hydrograph shows that the threshold for significant displacement was reached less than 0.03% of the time. Bedload transport occurs only during extreme meteorological events for cobbles with a diameter larger than 10 cm in a river such as Vieux-Habitants.

Published
2019

41. Geometry of meandering and braided gravel-bed threads from the Bayanbulak Grassland, Tianshan, P. R. China

Author

Métivier, François, primary, Devauchelle, Olivier, additional, Chauvet, Hugo, additional, Lajeunesse, Eric, additional, Meunier, Patrick, additional, Blanckaert, Koen, additional, Ashmore, Peter, additional, Zhang, Zhi, additional, Fan, Yuting, additional, Liu, Youcun, additional, Dong, Zhibao, additional, and Ye, Baisheng, additional

Published
2016
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42. Sediment transport by free-surface flows

Author

Devauchelle, Olivier, Institut Jean le Rond d'Alembert (DALEMBERT), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Pierre et Marie Curie, Stéphane Zaleski, Christophe Josserand, and Pierre-Yves Lagrée

Subjects
Rivière, Free-surface flow, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Sediment transport, Transport sédimentaire
Abstract

When water flows over a granular substrate at low Reynolds number, erosionmay generate various patterns (bars, braids, ripples or meanders), sometimes sur-prisingly similar to those naturally encountered in turbulent rivers. In a simple theo-retical frame (shallow-water equations and bedload transport), this study aims to ta-ckle this geomorphological problem using both analytical and numerical methods. Amass-conservative bank condition is established for micro-rivers, which allows oneto model the widening of a small flume of constant outflow through erosion. Thelinear stability of the same micro-rivers is performed in two dimensions. It is shownthat the influence of the erodible bank conditions can influence strongly the evolutionof the bank instability. The effects of non-linearity on the bank instability are studied by means of a finite-elements numerical scheme. Under certain circumstances,diamond-shaped erosion fronts can develop. The stability of sand ripples when thefree surface affects the flow is briefly studied. Finally, the lubrication theory is used todemonstrate that a moving contact line may stand on a porous plate, even for a vanishing contact angle, provided the dewetting process is slow enough. Furthermore,above a critical withdrawal velocity, a Landau-Levich-Derjagin film forms.; L’ écoulement laminaire d’un liquide sur un matériau granulaire conduit à la formation de divers motifs d’érosion, dont certains sont analogues aux bancs, méandres, tresses et rides rencontrés en Géomorphologie fluviale, où les écoulements sont pour-tant turbulents. En se fondant sur des modèles simples pour l’écoulement et le trans-port sédimentaire (équations de Saint-Venant, transport par charriage), la présenteétude aborde ces systèmes par des méthodes analytiques et numériques. Un modèlede conditions aux berges est établi pour des micro-rivières rectilignes dont les rivessont érodables, ce qui permet de prendre en compte la conservation du débit d’eauau cours du processus d’élargissement. La stabilité linéaire des mêmes micro-rivières éclaire différents mécanismes de morphogénèse, liés à l’instabilité de bancs, pourlesquels l’influence des conditions aux bords (`a deux dimensions) ne doit pas êtrenégligée. L'évolution non-linéaire de l’instabilité de banc conduit à l’apparition defronts d'érosion en forme de chevrons, parfois rencontrés en milieu naturel, selonun mécanisme fondé sur la non-linéarité de l’équation de transport. Le développe-ment des rides d'érosion est succinctement abordé dans le cas où l’influence de lasurface libre de l’écoulement ne peut être négligée. Enfin, la théorie de la lubrification est mise en œuvre pour établir l’existence d’une ligne de contact mobile sur un solide poreux extrait d’un bain liquide, et sa disparition au profit d’un film deLandau-Levich-Derjagin, au-delà d’une vitesse critique.

Published
2007

43. Écoulements de surface et érosion

Author

Devauchelle, Olivier, Institut Jean le Rond d'Alembert (DALEMBERT), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie, Stéphane Zaleski, Christophe Josserand, Pierre-Yves Lagrée, and Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
Rivière, Free-surface flow, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Sediment transport, Transport sédimentaire
Abstract

When water flows over a granular substrate at low Reynolds number, erosionmay generate various patterns (bars, braids, ripples or meanders), sometimes sur-prisingly similar to those naturally encountered in turbulent rivers. In a simple theo-retical frame (shallow-water equations and bedload transport), this study aims to ta-ckle this geomorphological problem using both analytical and numerical methods. Amass-conservative bank condition is established for micro-rivers, which allows oneto model the widening of a small flume of constant outflow through erosion. Thelinear stability of the same micro-rivers is performed in two dimensions. It is shownthat the influence of the erodible bank conditions can influence strongly the evolutionof the bank instability. The effects of non-linearity on the bank instability are studied by means of a finite-elements numerical scheme. Under certain circumstances,diamond-shaped erosion fronts can develop. The stability of sand ripples when thefree surface affects the flow is briefly studied. Finally, the lubrication theory is used todemonstrate that a moving contact line may stand on a porous plate, even for a vanishing contact angle, provided the dewetting process is slow enough. Furthermore,above a critical withdrawal velocity, a Landau-Levich-Derjagin film forms.; L’ écoulement laminaire d’un liquide sur un matériau granulaire conduit à la formation de divers motifs d’érosion, dont certains sont analogues aux bancs, méandres, tresses et rides rencontrés en Géomorphologie fluviale, où les écoulements sont pour-tant turbulents. En se fondant sur des modèles simples pour l’écoulement et le trans-port sédimentaire (équations de Saint-Venant, transport par charriage), la présenteétude aborde ces systèmes par des méthodes analytiques et numériques. Un modèlede conditions aux berges est établi pour des micro-rivières rectilignes dont les rivessont érodables, ce qui permet de prendre en compte la conservation du débit d’eauau cours du processus d’élargissement. La stabilité linéaire des mêmes micro-rivières éclaire différents mécanismes de morphogénèse, liés à l’instabilité de bancs, pourlesquels l’influence des conditions aux bords (`a deux dimensions) ne doit pas êtrenégligée. L'évolution non-linéaire de l’instabilité de banc conduit à l’apparition defronts d'érosion en forme de chevrons, parfois rencontrés en milieu naturel, selonun mécanisme fondé sur la non-linéarité de l’équation de transport. Le développe-ment des rides d'érosion est succinctement abordé dans le cas où l’influence de lasurface libre de l’écoulement ne peut être négligée. Enfin, la théorie de la lubrification est mise en œuvre pour établir l’existence d’une ligne de contact mobile sur un solide poreux extrait d’un bain liquide, et sa disparition au profit d’un film deLandau-Levich-Derjagin, au-delà d’une vitesse critique.

Published
2007

49. Erosion structures in laminar flumes

Author

Lagrée, Pierre-Yves, primary, Devauchelle, Olivier, additional, Thu-Lam, Khanh-Dang Nguyen, additional, Josserand, Christophe, additional, Lajeunesse, Éric, additional, Malverti, Luce, additional, Métivier, François, additional, Zaleski, Stéphane, additional, Nakagawa, Masami, additional, and Luding, Stefan, additional

Published
2009
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