Emmanuel Villermaux

Emmanuel Villermaux
Aix-Marseille Université | AMU ·  Institut de Recherche sur les Phénomènes Hors Equilibre (UMR 7342 IRPHE)

Professor, Institut Universitaire de France

About

237
Publications
62,335
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Introduction
Emmanuel Villermaux currently works at the Institut de Recherche sur les Phénomènes Hors Equilibre (UMR 7342 IRPHE), Aix-Marseille Université. Emmanuel does research on the Mechanics of Deformable Bodies, from Fluids to Solids, with a particular emphasis on Mixing and Fragmentation.
Additional affiliations
January 2000 - present
Institut de Recherche sur les Phénomènes Hors Equilibre
Position
  • Professor (Full)

Publications

Publications (237)
Article
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A general theory for predicting the distribution of scalar gradients (or concentration differences) in heterogeneous flows is proposed. The evolution of scalar fields is quantified from the analysis of the evolution of elementary lamellar structures, which naturally form under the stretching action of the flows. Spatial correlations in scalar field...
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A traditional hand-held firework generates light streaks similar to branched pine needles, with ever smaller ramifications. These streaks are the trajectories of incandescent reactive liquid droplets bursting from a melted powder. We have uncovered the detailed sequence of events, which involve a chemical reaction with the oxygen of air, thermal de...
Article
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We explore the processes by which a dense set of small liquid droplets (a spray) evaporates in a dry, stirred gas phase. A dense spray of micron-sized liquid (water or ethanol) droplets is formed in air by a pneumatic atomizer in a closed chamber. The spray is conveyed in ambient air as a plume whose extension depends on the relative humidity of th...
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When severely impacted, a cohesive object deforms and eventually breaks into fragments. Cohesion forces keeping the material together and momentum driving the fragmentation couple through a complicated process involving crack propagation on a deforming substrate, so that a comprehensive scenario for the build-up of the full fragment size distributi...
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The forced radial expansion of a spherical liquid shell by an exothermic chemical reaction is a prototypical configuration for the explosion of cohesive materials in three dimensions. The shell is formed by the capillary pinch off of a thin liquid annular jet surrounding a jet of reactive gaseous mixture at ambient pressure. The encapsulated gas in...
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The composition of the Earth's mantle, built by impacts of metallic core planetesimals, depends on the time offered to metal–silicate equilibration (concentration equalization by mixing) as the impactor fragments settle down. Smaller fragments equilibrate while bigger ones remain segregated and accumulate in the – therefore iron rich – Earth's core...
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The interplay between chemical reaction and substrate deformation is discussed by adapting Ranz's formulation for scalar mixing to the case of a reactive mixture between segregated reactants, initially separated by an interface whose thickness may not be vanishingly small. Experiments in a simple shear flow demonstrate the existence of three regime...
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Tiny water drops produced from bubble bursting play a critical role in forming clouds, scattering sunlight, and transporting pathogens from water to the air. Bubbles burst by nucleating a hole at their cap foot and may produce jets or film drops. The latter originate from the fragmentation of liquid ligaments formed by the centripetal destabilizati...
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DOI:https://doi.org/10.1103/PhysRevFluids.6.120001
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We introduce an original chemical reaction between two transparent reactant solutions (fluorescin and potassium ferricyanide), producing a fluorescent product in water (fluorescein). The reaction has a tunable kinetics, allowing the quantitative investigation of the interplay between molecular diffusion and reaction kinetics in various reactant fie...
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We show how the overall concentration distribution of the product in a randomly stirred reactive mixture is modified by the chemical reaction. We decipher the intermingled effects of stretching enhanced diffusion and chemical production on the evolution of each concentration level, and show why chemical kinetics contributes to a “rectification” mec...
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We report quantitative imaging experiments describing the three-dimensional (3D) bursting cascade of droplets from a liquid melt reacting with the oxygen of air which explode sequentially to produce ever smaller fragments. The 3D space-time resolved trajectories of the fragmenting drops reveal an arborescent structure of branchings defining the cas...
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The fragmentation of solid objects in turbulence is of paramount importance in a large number of situations, especially for marine plastic pollution where small plastic debris are formed by the fragmentation of plastic litter under hydrodynamic forces. Up to now, investigations have focused on the fragmentation of particle aggregates in turbulent f...
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We present results of a hybrid experimental, theoretical, and simulation-based investigation of the postbuckling behavior of thin elastic rods axially impacted by a projectile. We find a new postbuckling mechanism: mode coarsening. Much akin to inverse energy cascade phenomena in other nonlinear dynamic systems, energy is transferred during mode co...
Preprint
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The fluid flow through porous media is described by Darcy's law, while the fluid/wall interactions can be neglected. In nanopores, where adsorption dominates, Darcy's extension has been made, but approaches able to describe flows in mesopores are still lacking. We show here that molecular flows through nano-constrictions is well described by Berver...
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‘Fines’ from the collision of liquid rims – ERRATUM - Volume 894 - B. Néel, H. Lhuissier, E. Villermaux
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Drop fragmentation by laser-pulse impact - Volume 893 - Alexander L. Klein, Dmitry Kurilovich, Henri Lhuissier, Oscar O. Versolato, Detlef Lohse, Emmanuel Villermaux, Hanneke Gelderblom
Article
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‘Fines’ from the collision of liquid rims - Volume 893 - B. Néel, H. Lhuissier, E. Villermaux
Preprint
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We study the fragmentation of a liquid drop that is hit by a laser pulse. The drop expands into a thin sheet that breaks by the radial expulsion of ligaments from its rim and the nucleation and growth of holes on the sheet. By combining experimental data from two liquid systems with vastly different time- and length scales we show how the early-tim...
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The mixing of a passive scalar in a three-dimensional, statistically stationary turbulent Navier-Stokes flow at a constant and moderate Taylor microscale Reynolds number Rλ=42 is studied by means of direct numerical simulations for Schmidt numbers between 1 and 64. The freely decaying passive scalar is represented in two different ways: (1) in the...
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We study the mechanical response, and tearing features of crêpe paper, a two-dimensional, very anisotropic material, with one direction much less stiff than the other one. Depending on how the soft direction has been pre-stretched or not, the apparent Young modulus of the material can be varied over a broad range, while its fracture energy remains...
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Mixing is the operation by which a system evolves under stirring from one state of simplicity - the initial segregation of the constituents - to another state of simplicity - their complete uniformity. Between these extremes, patterns emerge, possibly interact, and die sooner or later. This review summarizes recent developments on the problem of mi...
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During the transport of colloidal suspensions in microchannels, the deposition of particles can lead to the formation of clogs, typically at constrictions. Once a clog is formed in a microchannel, advected particles form an aggregate upstream from the site of the blockage. This aggregate grows over time, which leads to a dramatic reduction of the f...
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We introduce a unified framework to discuss the emergence of corrugations on material interfaces transported by random media. Relating the shape of these interfaces to the stirring field giving birth to it, we formalize a population balance dynamics for the r-elements (segments of length r) needed to cover the interface contour in the course of its...
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We demonstrate the possibility to reproduce the experimental evolution of an interface, here a flame front, through the trajectory of a few poles whose position in the complex plane expresses the interface shape. These poles are analytical solutions of the Sivashinsky equation and they evolve according to an ordinary differential equation. The dire...
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Upon burst, surface bubbles transfer biological and chemical material from water bodies to the air we breathe via the production of droplets. An understanding of what shapes the size and payload of such droplets starts by understanding the fundamental physics of bubble birth, drainage and burst. Our combined experimental and theoretical investigati...
Article
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In many instances, sprays are formed from the breakup of liquid jets or sheets. We investigate the different parameters that determine the characteristic drop size in the breakup of sheets. We vary both the spraying parameters, such as the pressure and geometry of the nozzle, and the fluid parameters, such as viscosity and surface tension. The comb...
Article
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We call thick those films for which the disjoining pressure and thermal fluctuations are ineffective. Water films with thickness $h$ in the $1{-}100~\unicode[STIX]{x03BC}\text{m}$ range are thick, but are also known, paradoxically, to nucleate holes spontaneously. We have uncovered a mechanism solving the paradox, relying on the extreme sensitivity...
Article
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The diffusive strip method (DSM) is a near-exact numerical method for mixing computations initially developed in two dimensions (Meunier & Villermaux, J. Fluid Mech. , vol. 662, 2010, pp. 134–172). The method, which consists of following stretched material lines to compute the resulting scalar field a posteriori , is extended here to three-dimensio...
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Using a technique allowing for in situ measurements of concentrations fields, the evolution of scalar mixtures flowing within a porous medium made of a three-dimensional random stack of solid spheres, is addressed. Two distinct fluorescent dyes are injected from separate sources. Their evolution as they disperse and mix through the medium is direct...
Article
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We explore the consequences of a point of view stating that fracture in strained brittle solids results from the action of mechanically activated random fluctuations. As opposed to thermally activated fracture, the energy reservoir feeding the crack progression is given by the mean elastic energy stored in the cracked region, itself a sub-sample of...
Article
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Making use of an original technique which permits the simultaneous measurement of both the displacement field of evaporating droplets in a spray, and of their vapor, we investigate the relevance of a scenario introduced earlier to describe the evaporation dynamics of dense sprays [Phys. Rev. Fluids 1, 014201 (2016)]. A plume of dense acetone drople...
Conference Paper
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We study the transport and diffusion of a scalar in a two-dimensional flow generated by the co-rotation of two cylinders and perturbed periodically by an oscillating cylinder. The flow is both stratified with a linear density gradient using salted water, and viscous in order to prevent Ekman pumping and centrifugal instabilities. The evolution of a...
Article
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We experimentally investigate mixing in sheared particulate suspensions by measuring a crucial kinematic quantity of the flow: the stretching laws of material lines in the suspending liquid. High-resolution PIV measurements in the fluid phase are performed to reconstruct, following the Diffusive Strip Method (\cite{Meunier}), the stretching histori...
Article
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A liquid jet falling by gravity ultimately destabilizes by capillary forces. Accelerating as it falls, the jet thins and stretches, causing a capillary instability to develop on a spatially varying substrate. We discuss quantitatively the interplay between instability growth, jet thinning and longitudinal stretching for two kinds of perturbations,...
Article
Full-text available
We experimentally investigate mixing in sheared particulate suspensions by measuring a crucial kinematic quantity of the flow: the stretching laws of material lines in the suspending liquid. High-resolution PIV measurements in the fluid phase are performed to reconstruct, following the Diffusive Strip Method (Meunier 2010), the stretching histories...
Conference Paper
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We study the intrinsic dynamics of cusps, or indentations, moving along a liquid sheet border, and characterize their ensemble statistics. Gordillo and collaborators [J. Fluid Mech. 754, R1 (2014)] have shown that the symmetrical stationary cusp is the only structure accommodating for both mass and momentum conservation at a steadily receding liqui...
Conference Paper
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Nous étudions la réponse d'une membrane initialement au repos à un impact transverse. Nous montrons qu'une instabilité élastique conduit à la formation de plis radiaux centrés sur le point d'impact. Nous discutons le lien entre le motif observé et le motif de fragmentation observé lors de la brisure par impact des plaques fragiles.
Article
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A cohesive object will eventually break into fragment when experiencing a strong deformation, during an impact for instance. Using necklaces of cohesive magnetized spheres suddenly expanded, we have shown that the fragmentation of this one-dimensional material results from an inverse aggregation cascade (Vledouts et al. 2015 Proc. R. Soc. A 471, 20...
Article
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A free-falling absorbing liquid drop hit by a nanosecond laser-pulse experiences a strong recoil-pressure kick. As a consequence, the drop propels forward and deforms into a thin sheet which eventually fragments. We study how the drop deformation depends on the pulse shape and drop properties. We first derive the velocity field inside the drop on t...
Article
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The impact of a laser pulse on a highly absorbing liquid drop can lead to a violent response: the drop is accelerated, strongly deforms, and eventually fragments. Shock waves, the ejection of matter, and even plasma formation can accompany this process ...
Article
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We report on a new method for realizing an exceptionally strong inertial confinement of a gas in a liquid: A centimetric spherical bubble filled with a reactive gaseous mixture in a liquid is expanded by an exothermic chemical reaction whose products condense in the liquid at the bubble wall. Hence, the cavity formed in this way is essentially empt...
Article
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We study the transport properties of a genuine two-dimensional flow with a large mean velocity perturbed periodically in time by means of an original experimental technique. The flow generated by the co-rotation of two cylinders is both stratified with a linear density gradient using saltedwater and viscous in order to prevent Ekman pumping and cen...
Article
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We develop a general framework for modelling mixing in porous media flows, in which the scalar mixture is represented as an ensemble of lamellae evolving through stretching, diffusion and coalescence. Detailed numerical simulations in Darcy scale heterogeneous permeability fields are used to analyse the lamella deformation process, which controls t...
Article
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We show how the deposition of laser energy induces propulsion and strong deformation of an absorbing liquid body. Combining high speed with stroboscopic imaging, we observe that a millimeter-sized dyed water drop hit by a millijoule nanosecond laser pulse propels forward at several meters per second and deforms until it eventually fragments. The dr...
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We investigate the dispersion of a layer of dye initially applied at the outer wall of a cylindrical Couette-cell into a sheared suspension of non-Brownian spherical particles. The process is directly visualized and quantified at the particle scale. A “rolling-coating” mechanism is found to convectively transport the dye at a constant rate directly...
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We study the short-time dynamics of a liquid ligament, held between two solid cylinders, when one is impulsively accelerated along its axis. A set of one-dimensional equations in the slender-slope approximation is used to describe the dynamics, including surface tension and viscous effects. An exact self-similar solution to the linearized equations...