A5082126259- Hydrology and Sediment Transport Processes
- Hydrology and Watershed Management Studies
- NMR spectroscopy and applications
- Soil erosion and sediment transport
- Groundwater flow and contamination studies
- Landslides and related hazards
- Lattice Boltzmann Simulation Studies
- Theoretical and Computational Physics
- Diabetes Management and Research
- Hydrocarbon exploration and reservoir analysis
- Quantum chaos and dynamical systems
- Hydraulic flow and structures
- Seismic Imaging and Inversion Techniques
- Stochastic processes and statistical mechanics
- Enhanced Oil Recovery Techniques
- Fluid Dynamics and Turbulent Flows
- Nonlinear Dynamics and Pattern Formation
- Diabetes, Cardiovascular Risks, and Lipoproteins
- Soil and Water Nutrient Dynamics
- Geophysical and Geoelectrical Methods
- Cyclone Separators and Fluid Dynamics
- Cryospheric studies and observations
- Combustion and flame dynamics
- Granular flow and fluidized beds
- Cardiovascular and exercise physiology
Université de Rennes
2019-2024
Géosciences Rennes
2017-2024
Centre National de la Recherche Scientifique
2016-2024
Unité de Recherche Pluridisciplinaire Sport, Santé, Société
2022
Université de Lille
2022
RMIT University
2021
Indian Institute of Technology Kharagpur
2020
Institut de Physique de Rennes
2016-2017
École Polytechnique Fédérale de Lausanne
2012-2016
Université de Bretagne Sud
2013
Abstract This paper concerns a model of bed load transport, which describes the advection and dispersion coarse particles carried by turbulent water stream. The challenge is to develop microstructural approach that, on one hand, yields parsimonious description particle transport at microscopic scale and, other leads averaged equations macroscopic that can be consistently interpreted in light continuum used hydraulics. cornerstone theory proper determination flux fluctuations. Apart from...
Significance Porous media flows are central to environmental, industrial, and biological systems, where they transport molecules, particles, microorganisms trigger important biogeochemical reactions. There is increasing evidence that many of these processes highly sensitive chemical gradients below the pore-scale. However, it unknown how porous architectures control microscale concentration heterogeneities. Here, we provide high-resolution experimental images fully resolve three-dimensional...
Spectral induced polarization (SIP) has the potential for monitoring reactive processes in subsurface. While strong SIP responses have been measured response to calcite precipitation, their origin and mechanism remain debated. Here we present a novel geo-electrical millifluidic setup designed observe microscale transport while performing measurements. We precipitation by injecting two solutions into porous medium, which led highly localized precipitates at mixing interface. Strikingly,...
This article examines the spatial {dynamics of bed load particles} in water. We focus particularly on fluctuations particle activity, which is defined as number moving particles per unit {length}. Based a stochastic model recently proposed by \citet{Ancey2013}, we derive second moment activity analytically; that correlation functions activity. From these expressions, show large clusters can develop spatially. Also, provide evidence are scale-dependent. Two characteristic lengths emerge from...
The advection-diffusion equation is one of the most widespread equations in physics. It arises quite often context sediment transport, e.g., for describing time and space variations particle activity (the solid volume particles motion per unit streambed area). Phenomenological laws are usually sufficient to derive this interpret its terms. Stochastic models can also be used it, with significant advantage that they provide information on statistical properties activity. These useful when...
The $\mu(I)$-rheology has been recently proposed as a potential candidate to model the flow of frictional grains in dense inertial regime. However, this rheology was shown be ill-posed mathematical sense for large range parameters, notably slow and fast limits \citep{Barker2015}. In rapid communication, we extend stability analysis compressible flows. We show that compressibility regularizes mostly equations, making them well-posed all at condition sufficient dissipation is associated with...
Steady laminar flows through porous media spontaneously generate Lagrangian chaos at pore scale, with qualitative implications for a range of transport, reactive and biological processes. The characterization understanding mixing dynamics in these opaque environments is an outstanding challenge. We address this issue by developing novel technique based upon high-resolution imaging the scalar signature produced push-pull samples. Owing to rapid decorrelation particle trajectories chaotic...
Hyporheic fluxes are typically regarded as highly variable both in space and time at the stream‐groundwater interface. However, Active‐Distributed Temperature Sensing (DTS) experiments conducted a losing river section demonstrated low spatial variability (one order of magnitude) remarkable temporal stability. In this abstract, we investigate potential reasons for observed notable stability hyporheic flows.Experiments were by burying several hundred meters heatable...
Geochemical reactions in porous rocks are typically scaled up using effective reaction parameters derived under well-mixed conditions. Such conditions often absent natural settings. While conventional transport theories based fundamentally on diffusion and dispersion processes can not fully capture the state of mixing, several lines evidence point to dominance chaotic solute mixing. Yet, proving existence mixing remains unresolved mostly due limitations directly observing pore-scale...
Groundwater flow is subject to transients, due natural events or human activities (recharge, tides, decontamination, etc.). The occurrence of such temporal fluctuations in the field can have significant impact on reactive transport processes, compared steady conditions, especially fronts. These fronts manifest as localized interfacial regions where chemical reaction occurs an ambient that brings two more reactants contact with each other. Understanding how evolve during transient flows...
Steep slope streams show large fluctuations of sediment discharge across several time scales. These may be inherent to the internal dynamics transport process. A probabilistic framework thus seems appropriate analyze such a In this paper, we present an experimental study bedload over steep flume for small moderate Shields numbers. The sampling technique allows acquisition high‐resolution series solid discharge. resolved scales range from 10 − 1 s up 5 s. We that two distinct can observed in...
In gravel-bed rivers, bedload transport exhibits considerable variability in time and space. Recently, stochastic theories have been developed to address the mechanisms effects of fluctuations. Stochastic models involve parameters such as particle diffusivity, entrainment deposition rates. The lack hard information on how these vary with flow conditions is a clear impediment their application real-world scenarios. this paper, we determined closure equations for above from laboratory...
This paper describes the relationship between statistics of bed load transport flux and timescale over which it is sampled. A stochastic formulation developed for probability distribution function flux, based on Ancey et al. (2008) theory. An analytical solution variance differing sampling timescales presented. The demonstrates that dependence reduces to a three-regime relation demarcated by an intermittency (tI) memory (tc). As increases, this passes through intermittent stage (≪tI),...
We study the Lagrangian kinematics of steady three-dimensional Stokes flow over simple cubic (SC) and body-centred (BCC) lattices close-packed spheres, uncover mechanisms governing chaotic mixing in these crystalline structures. Due to cusp-shaped sphere contacts, topology skin friction field is fundamentally different that continuous (non-granular) media, such as open pore networks, with significant implications for fluid mixing. Weak symmetry breaking orientation respect lattice symmetries...
Mixing-induced reactions play a key role in large range of biogeochemical and contaminant transport processes the subsurface. Fluid flow through porous media was recently shown to exhibit chaotic mixing dynamics at pore scale, enhancing microscale concentration gradients controlling rates. While this phenomenon is likely ubiquitous environmental systems, it not known how affects chemical reactions. Here, we use refractive index matching laser-induced fluorescence imaging bimolecular redox...
Chemical and biological reactions at fluid-solid interfaces are central to a broad range of porous material applications research. Pore-scale solute transport limitations can reduce reaction rates, with marked consequences for wide spectrum natural engineered processes. Recent advances show that chaotic mixing occurs spontaneously in media, but its impact on surface is unknown. We pore-scale significantly increases efficiency compared nonchaotic flows. find rates well described terms...
Acoustic Doppler velocity profilers (ADVP) measure the simultaneously in a linear array of bins. They have been successfully used past to three-dimensional turbulent flow and dynamics suspended sediment. The capability ADVP systems bedload sediment flux remains uncertain. main outstanding question relates physical meaning measured region where transport occurs. hypothesis paper, that measures moving particles, is validated laboratory experiments range from weak intense transport. First,...
This thesis addresses the problem of a statistical description transport sediment as bed load. It highlights role fluctuations arising during process, and their impact on macroscopic averages. The results presented here are based four experimental studies. Two them were published recently by Bohm et al. [2004] Roseberry [2012] while other two carried out thesis. In particular, high speed cameras used to automatically reconstruct particle trajectories over window approximately 1mlength,...
Abstract Mixing fronts at the interface of opposing flows are compressed a constant rate. The resulting exponential stretching fluid elements leads to enhanced chemical gradients and biogeochemical processes. This process is similar as what occurs in pore space 3D chaotic flows. However, it so far not known how such compression controls amplitude mixing reaction rates porous media. Here we derive analytical predictions for width, maximum rate intensity function Péclet Damköhler numbers. We...
Abstract Characterizing the spatiotemporal variability of water fluxes at stream‐groundwater interface is extremely challenging due to lack methods for estimating hyporheic flows different scales. To address this, we demonstrate potential Active‐Distributed Temperature Sensing (DTS) measuring and mapping flow in a lowland stream. Experiments were conducted by burying few hundred meters heatable Fiber‐Optic cables within streambed sediments large meander, where permanent stream‐losing...
Mixing describes the process by which solutes evolve from an initial heterogeneous state to uniformity under stirring action of a fluid flow. Fluid stretching forms thin scalar lamellae that coalesce due molecular diffusion. Owing linearity advection–diffusion equation, coalescence can be envisioned as aggregation process. Here, we demonstrate in smooth two-dimensional chaotic flows, mixing obeys correlated process, where spatial distribution number aggregates is highly with their...
Oscillatory kinetics coupled to diffusion can produce traveling waves as observed in physical, chemical, and biological systems. We show experimentally that the properties of such be controlled by fluid stretching compression a hyperbolic flow. Localized packet consisting train parallel develop due balance between diffusive broadening advective along unstable manifold. At given distance from stagnation point, transform into planelike smeared where transverse parabolic flow profile disturbs...