Teses / dissertações sobre o tema "Dynamique des particules d'inertie"
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Ferran, Amélie. "Dynamique des particules d'inertie dans une interface turbulente/non turbulente". Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALI102.
Texto completo da fonteThis experimental project will investigate the dynamics of droplets at the interface between turbulent and non-turbulent regions, with shear. To conduct this research, we will utilize unique facilities and measurement techniques, namely two wind tunnels equipped with turbulence-generating systems that can be differentially activated to create a turbulent/non-turbulent interface. This collaboration will cover a wide range of turbulent intensity gradients, shear rates, and Reynolds numbers for studying the dynamics of inertial particles in turbulent/non-turbulent conditions. The study will produce data on various droplet sizes spanning the range of Stokes numbers, characterizing particle inertia relative to the micrometric scale of turbulence. Potential applications include fuel injection in energy conversion systems, industrial spray coating, warm rain formation in clouds, and sea spray in the surf zone
Louazel, Stéphanie. "Influence des ondes d'inertie-gravité sur la dynamique tourbillonaire". Brest, 2004. http://www.theses.fr/2004BRES2016.
Texto completo da fonteThe purpose of this thesis is to study the influence of inertia-gravity waves on eddies dynamics, this process being part of the intercation between slow and fast dynamics of oceanic flows. Eddies dynamics is indeed slow but it is also intermediate between the fast inertia-gravity waves dynamics and the very slow frequency dynamics of general circulation. The first part reviews the literature on this interaction. Then two numerical studies are performed. The first one concerns the influence of inertia-gravity waves on the filamentation process is found to be slightly altered. However, the information required to analyse the filamentation process is shown to be entirely captured by the slow component of the flow and regions of filament ejection can be identified from the diagnostic criterion of Lapeyre et al. (1999) based on instateneous slow quantities. The second numerical study shows that inertia-gravity waves alter eddies interaction. For that purpose, the tripolar vortex is used as an academic example of an eddies intercation. The core of such a structure may split if the two satellites are strong enough. For all cases of waves that have been tested, the structure is systematically stabilized : the core breaks down more easily without inertia-gravity waves than in their presence
Plougonven, Riwal. "Jets, vortex et ondes d'inertie-gravité : séparation dynamique et émission". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00011940.
Texto completo da fonteL'analyse de radiosondages de la campagne FASTEX montre que les jets et les fronts atmosphériques aux moyennes latitudes sont des sources importantes d'ondes de gravité.
Un mécanisme d'excitation d'ondes de gravité à partir de mouvements vorticaux est analysé théoriquement dans le cadre d'un fluide stratifié, pour les ondes excitées par un tourbillon ellispoïdal.
De, Souza David. "Dynamique de sédimentation de particules". Thesis, Institut polytechnique de Paris, 2021. http://www.theses.fr/2021IPPAE003.
Texto completo da fonteThe dynamics of heavy inertial particles evolving in a fluid are of interest in many fields.They are found both in nature (water droplets in clouds, sediments in rivers and in the oceans, planetary accretion disks) and in human activities and technological applications (fuel drops in combustion chambers, chemical reactors).These systems are complex, their modelling using often strong simplifying hypotheses, and experimental data is still required in their study.A large range of behaviours can be found in such dispersed two-phase flows.This work focuses on two of these.The first is clustering, or the observation that particles accumulate in specific regions and leave others void.The second is settling velocity alteration, as particles have been observed to fall either faster or slower than in a quiescent fluid.These two phenomena are intertwined, and depend on parameters like the size and density of the particles, what the carrier phase is (water or air usually) and whether it is in a quiescent or turbulent state.An experimental device was built in which small (diameters of at most 200 µm) solid particles settle in water.Particles of various densities have been separated by size by sieving.This allows access to a large variety of particle properties.An easy to implement double-measurement technique allowing simultaneous measurements of particle and fluid velocities was developed, providing insight into particle-fluid interactions that was seldomly achieved in previous works.Increases of the settling velocity of particles falling in a quiescent fluid have been observed and could be attributed to the development of a flow that pushes the particles down.Voronoï analysis were also performed, but could not confirm with certainty whether particles formed clusters or not.This work gives interesting data, relevant in the study of particles settling in quiescent fluids in closed spaces.It also provides a reference point for future works where turbulence will be added to the system
Rodrigue, Denis. "Dynamique de particules en milieu non-newtonien". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21861.pdf.
Texto completo da fonteBertho, Yann. "Dynamique d'écoulements gaz-particules en conduite verticale". Palaiseau, Ecole polytechnique, 2003. https://pastel.archives-ouvertes.fr/tel-00171722.
Texto completo da fonteBen, Jelloul Mahdi. "Tourbillons et fronts dans l'océan et l'atmosphère : dynamique, stabilité et interactions avec les ondes d'inertie-gravité". Paris 6, 2001. http://www.theses.fr/2001PA066016.
Texto completo da fonteOuari, Bachir. "Dynamique de l'aimantation des particules superparamagnétique avec anisotropie triaxiale". Perpignan, 2006. http://www.theses.fr/2006PERP0739.
Texto completo da fonteIn this thesis, a theoretical study of the dynamics of the magnetization of superparamagnetic nanoparticles with triaxial (orthorhombic) anisotropy has been carried out using the Néel-Brown model. Numerical and analytical solutions of the Fokker-Planck equation given by Brown, which describes the relaxation of the magnetization in the nanoparticles, have been obtained in order to facilitate this study. The process of relaxation of the magnetization is characterized by the longest relaxation time, integral relaxation time, and, in the frequency domain, by the longitudinal and transverse components of the magnetic susceptibility tensor. The numerical solutions allows us to evaluate these characteristics for typical values of the dissipation constant α, temperature T, anisotropy constants with and without a uniform external magnetic field H0. By using the approach of Kramers-Brown-Coffey, analytical equations for the magnetization relaxation times and for the longitudinal and transversals components of the magnetic susceptibility have been deduced. These analytical equations are in complete agreement with the results of our numerical calculations. They have simple analytical forms and allow one to quantify the dependence of the relaxation times and the magnetic susceptibility on the temperature T, angular frequency , strength of the external field H, and dissipation constant α. Moreover they can be used to estimate the relaxation times and the magnetic susceptibility in wide ranges of variation of T,, H, and α. The results obtained may be considered as a complete solution of the problem of relaxation of the magnetization in nano particles with triaxial anisotropy
Candelier, Fabien. "Étude du mouvement libre d'une particule dans un fluide en rotation solide à faibles nombres de Reynolds : mise en évidence des forces d'histoire et d'inertie". Vandoeuvre-les-Nancy, INPL, 2005. http://docnum.univ-lorraine.fr/public/INPL_T_2005_CANDELIER_F.pdf.
Texto completo da fonteThe motion of a spherical inclusion released in a vertical solid-body rotation flow is investigated theoretically and experimentally. Solid spheres, bubbles and drop are considered. The particle Reynolds number and the Taylor number nimber are smaller than unity. The motion equations of the inclusion are obtained by revisiting the hydrodynamic equations. The axial (vertical) motion and the horizontal motion are uncoupled, even though they are sensitive to the rotation rate of the flow. Analytical solutions of the particle motin equation are compared to experimental results obtained by releasing a particle in a rotating tank filled-up with silicone oil. For solid spheres and bubbles, both the terminal velocity and the particle ejection rate (or trapping rate) predicted by the theory agree with experiments, without any empirical adjustment. Ln particular, the experimental device enables to check the validity of various theories involving solid or fluid inclusions with or without inertia or history effects. Ln agreement with Miyazaki's theory (1995), the mobility tensor of Herron, Davis and Bretherton (1975), obtained by writing the fluid motion equations in the rotating frame, accurately predicts the horizontal particle trajectory, like the Boussinesq-Basset equation obtained by writing the fluid motion equations in the non-rotating frame and neglecting the horizontal contribution of inertia effects
Simon, Frédéric. "Comportement dynamique des joints annulaires à fuite : modélisation des forces d'inertie convective en régime turbulent stationnaire et instationnaire". Poitiers, 1989. http://www.theses.fr/1989POIT2335.
Texto completo da fonteCaussin, Jean-Baptiste. "Dynamique collective de particules auto-propulsées : ondes, vortex, essaim, tressage". Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL0996/document.
Texto completo da fonteThe emergence of coherent motion at large scale has been widely observed in animal populations (bird flocks, fish schools, bacterial swarms...) and more recently in artificial systems. Such ensembles of self-propelled individuals, capable of aligning their velocities, are commonly referred to as polar active materials. They display unique physical properties, which we investigate in this theoretical thesis.We first describe a population of self-propelled colloids. In strong connection with the experiments, we model the dynamics from the individual level to the macroscopic scale. The theoretical results account for the emergence and the structure of coherent patterns: (i)~transition to collective motion, (ii)~propagation of polar spatial structures, (iii)~damping of density fluctuations in a polar liquid, (iv)~heterogeneous vortex in confined geometries.We then follow a more formal perspective, and study the non-linear excitations which propagate in polar active systems. We analyze the hydrodynamic theories of active matter using a dynamical-system framework. This approach makes it possible to rationalize the experimental and numerical observations reported so far.Finally, we propose a complementary approach to characterize active populations. Combining numerical and analytical results, we study the geometric properties of the individual trajectories and their entanglement within three-dimensional flocks. We suggest that these observables should provide powerful tools to describe animal flocks in the wild
Lyu, Jinming. "Modélisation numérique de la dynamique de particules molles en microcanaux". Thesis, Ecole centrale de Marseille, 2019. http://www.theses.fr/2019ECDM0002.
Texto completo da fonteVesicles are a model system for understanding the dynamical behavior of a closed soft particle such as red blood cells (RBCs) in flows. The inextensible lipid bilayer membrane of a vesicle admits resistance to the bending elasticity, and its large surface-area-to-volume ratio allows the vesicle to exhibit remarkable shape changes in the dynamics even in a simple flow. Significant progress has been made over the past decades in understanding vesicle dynamics in unbounded Stokes flows. This manuscript deals with the numerical investigation of shape transition and lateral migration of 3D vesicles in wall-bounded Stokes flows by means of an isogeometric finite-element method (FEM) and boundary-element method (BEM). Starting from a previously reported isogeometric FEM-BEM simulations of the dynamics of soft particles (drops, capsule, and vesicle) in Stokes flows in free space, the original code is developed to account for microchannel walls of arbitrary cross-section. The present work focuses on the dynamics of a vesicle that is transported through a circular tube in a pressure-driven flow. First, we investigate typical vesicle shapes, different lateral migration modes, and flow structure onto vesicle membrane versus three independent dimensionless parameters, namely, the reduced volume, the confinement, and the (bending) capillary number. Shape transitions and the phase diagram of stable shapes for several reduced volumes are obtained in the (confinement, capillary number) space, showing an extension of the set of vesicle morphologies and rich vesicle dynamics owing to the intricate interplay among the tube wall, hydrodynamic stresses, and membrane bending. Secondly, we study, via an axisymmetric BEM, the hydrodynamics under high confinements in which the shape of the vesicle is expected to maintain axisymmetry. A particular emphasis is given to the prediction of the vesicle mobility and the extra pressure drop caused due to the presence of the vesicle, the latter having implications in the rheology of a dilute suspension. In addition, based on the numerical results of limiting behavior of quantities of interest near maximal confinement, we give various scaling laws to infer, for example, the vesicle velocity, its length, and the thickness of lubrication film. Finally, we present a coupled, hybrid continuum–coarse-grained model for the study of RBCs in fluid flows. This model is based on a combination of the vesicle model with a network of springs with fixed connectivity, representing the cytoskeleton. Numerical results show that this two-component vesicle–cytoskeleton model isable to extract the mechanical properties of RBCs and predict its dynamics in fluid flows
Al, Haj Mohammad. "Modèles discrets de dislocations : ondes progressives et dynamique de particules". Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1001/document.
Texto completo da fonteThis work focuses on the study of the dislocation dynamics in the crystal lattice and it is splitted into two parts : the first part is concerned with the horizontal motion of a chain of interacting atoms containing a dislocation. While, the second part deals with the accumulation of dislocations forming what is known as walls of dislocations. In the first part, we consider a fully nonlinear generalization of the discrete reaction diffusion equations “fully overdamped Frenkel-Kontorova models” that describe the dynamics of crystal defects (dislocations) in a lattice. We study both : the bistable and the monostable non-linearities. Under sufficient conditions, we show the existence and uniqueness of traveling wave solution for the bistable non-linearity case. For the monostable case, we study the existence of branch of traveling waves solutions for general Lipschitz non-linearity. We also prove that the minimal velocity is non-negative and bounded below. In this part, we as well study the generalization of Frenkel-Kontorova model for which we can add a driving force parameter. We also illustrate, in this case, the variation of the velocity of propagation of traveling waves in terms of the parameter force. In the second part, we study the accumulation of dislocations in walls of dislocations. We prove actually the convergence of several interacting dislocations to walls of dislocations. We also present results of some numerical experiments that confirm the theoretical results that we obtain
Erignoux, Clément. "Limite hydrodynamique pour un dynamique sur réseau de particules actives". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX011/document.
Texto completo da fonteCollective dynamics can be observed among many animal species, and have given rise in the last decades to an active and interdisciplinary field of study. Such behaviors are usually modeled by active matter, in which each individual is self-driven and tends to align its velocity with that of its neighbors.In a classical model introduced by Vicsek & al., as well as in numerous related active matter models, a phase transition between chaotic behavior at high temperature and global order at low temperature can be observed. Even though ample evidence of these phase transitions has been obtained for collective dynamics, from a mathematical standpoint, such active systems are not fully understood yet. Some progress has been achieved in the recent years under an assumption of mean-field interactions, however to this day, few rigorous results have been obtained for models involving purely local interactions.In this manuscript, we describe a lattice active particle system interacting locally to align their velocities. This thesis aims at rigorously obtaining, using the formalism developed for hydrodynamic limits of lattice gases, the scaling limit of this out-of-equilibrium system, for which numerous technical and theoretical difficulties arise
Gautier, Pierre-Etienne. "Comportement dynamique des véhicules ferroviaires : caractérisation expérimentale d'éléments de suspension : analyse modale et détermination des paramètres d'inertie des caisses". Châtenay-Malabry, Ecole centrale de Paris, 1985. http://www.theses.fr/1985ECAP0010.
Texto completo da fonteAchour, Louiza. "Dynamique et contrôle de la régénération d'un filtre à particules diesel". Paris, ENMP, 2001. http://www.theses.fr/2001ENMP1004.
Texto completo da fonteLecolier, Eric. "Suspensions aqueuses de particules colloidales anisotropes et chargees : structure et dynamique". Orléans, 1998. http://www.theses.fr/1998ORLE2014.
Texto completo da fonteLafleche, Laurent. "Dynamique de systèmes à grand nombre de particules et systèmes dynamiques". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLED010.
Texto completo da fonteIn this thesis, we study the behavior of solutions of partial differential equations that arise from the modeling of systems with a large number of particles. The dynamic of all these systems is driven by interaction between the particles and external and internal forces. However, we will consider different scales and travel from the quantum level of atoms to the macroscopic level of stars. We will see that differences emerge from the associated dynamics even though the main properties are conserved. In this journey, we will cross the path of various applications of these equations such as astrophysics, plasma, semi-conductors, biology, economy. This work is divided in three parts.In the first one, we study the semi classical behavior of the quantum Hartree equation and its limit to the kinetic Vlasov equation. Properties such as the propagation of moments and weighted Lebesgue norms and dispersive estimates are quantified uniformly in the Planck constant and used to establish stability estimates in a semiclassical analogue of the Wasserstein distance between the solutions of these two equations.In the second part, we investigate the long time behavior of macroscopic and kinetic models where the collision operatoris linear and has a heavy-tailed local equilibrium, such as the Fokker-Planck operator, the fractional Laplacian with a driftor a Linear Boltzmann operator. This let appear two main techniques, the entropy method and the positivity method.In the third part, we are interested in macroscopic models inspired from the Keller-Segel equation, and we study therange of parameters under which the system collapses, disperses or stabilizes. The first effect is studied using appropriate weights, the second using Wasserstein distances and the third using Lebesgue norms
Pergolizzi, Benjamin. "Étude de la dynamique des particules inertielles dans des écoulements aléatoires". Nice, 2012. http://www.theses.fr/2012NICE4101.
Texto completo da fonteThis thesis deals with the dynamics of inertial particles in non-stationary flows. Whether there are droplets in warm clouds or dust grains in circumstellar disks, such impurities decouple from the flow dynamics and distribute in a heterogeneous manner. Modeling the microphysical interactions between particles thus requires understanding and quantifying this phenomenon of preferential concentration. The origin of such heterogeneities is explained by the simultaneous presence of two mechanisms. On the one hand particles inertia make them detach by centrifugal effect from the flow vortices and concentrate in straining regions. On the other hand, as the particle dynamics is dissipative, they concentrate at long times on a fractal attractor. Such effects are generally studied separately by considering either stationary flows or flows without temporal correlation and thus where structures are absent. In this thesis, I introduce a random flow model having a finite correlation time (measured by a Kubo number) that encompasses these two cases. This approach allows me to identify and study analytically various regimes of the particle dynamics as a function of this parameter and of the Stokes number that measures particle inertia. The richness of this model gives evidence of how complex is the interference between the two mechanisms leading to preferential concentration
Sarrot, Vincent. "Capture de fines particules par des inclusions fluides". Toulouse, INSA, 2006. http://eprint.insa-toulouse.fr/archive/00000189/.
Texto completo da fonteThis study focuses on the collision mechanism between a spherical bubble and particles when the particle diameter remains less than some percents of the bubble diameter. This situation corresponds to the first step of the particle capture in flotation processes. The efficiency determination is based on experimental measurements and Direct Numerical Simulations (DNS). Experimentally, a single bubble flotation cell has been build for the purpose of measuring capture efficiency. Small spherical bubbles are created by a capillary tube and then arise through a suspension capturing glass particles. Captured particles are recovered by overflow and are counted in a particle counter. Results are analysed and the magnitude is favorably compared to those of Ralston et al. (1999a). Efficiencies exhibit a general decreasing trend with particle to bubble diameters ratio dp/db, in opposition to the trend analytically predicted by collision efficiency models in litterature. This effect seems to be due to wetting properties of particles. Numerically, the flow around the bubbles is computed and particle trajectories determined. Particle with Stokes number less than 1 follow the streamlines. In this case, the collision efficiency only depends on the shape of the streamlines and on the size of the particles. Numerical simulations have been performed over large parameter ranges (particle to bubble diameters ratio, Reynolds number of the bubble and the degree of contamination of the bubble surface). The collision efficiency is found to increase with the Reynolds number and significantly decrease with the level of contamination. For clean (respectively fully contaminated) spherical bubbles, the efficiency evolves as dp/db (respectively (dp/db)2), whatever the bubble Reynolds number and the particle size. For partially contaminated bubbles, efficiency can be scaled with dp/db or (dp/db)2 depending on both the level of contamination and the particle size. Correlations of the numerical results are proposed for efficiencies versus dp/db, bubble Reynolds number and interface contamination degree
Oubal, Mohamed. "Etude théorique de la réactivité des particules de suie émises par les avions". Besançon, 2011. http://www.theses.fr/2011BESA2042.
Texto completo da fonteIn this work, we presented, a theoretical study, at the molecular level of interactions between atmospheric species and soot particles emitted by aircraft. This work is organized following different axes, the main goals of which being twofold. On the one hand, we aimed at better understanding the mechanisms of reactivity on the surface of carbonaceous particles, in particular toward the aatmospheric oxidants such as O,O2, H2O, and some radicals such as OH. On the other hand, we wanted to give to the atmospheric science community some elements to understand and interpret hydrophilic properties of soot and their impact on the reactivity of molecules of polycyclic aromatic hydrocarbons (PAHS) in the troposphere
Allende, Sofia. "Dynamique et statistiques de particules allongées et flexibles dans des écoulements turbulents". Thesis, Université Côte d'Azur, 2021. https://tel.archives-ouvertes.fr/tel-03284996.
Texto completo da fonteThis thesis analyses the dynamics of small complex objects immersed in a turbulent environment. Turbulent flows are akin to apparent random fields, that usually display very non-Gaussian and fluctuating statistics, and which are known to enhance the mixing and the transport of the objects that they carry. Here, we focus on the transport of small complex particles, which are characterized by a non-trivial interplay between their mass, their shape and their rheology. Our aim is to gain a physical understanding on how turbulent fluctuations prescribe the dynamics of such complex particles, and lead to various physical phenomena, including preferential concentration, their deformation or catastrophic events such as their fragmentation. Studying such phenomena is relevant for both industrial and sustainability issues. For instance, while volcanic ash has direct impacts for the commercial flight industry, the blooming of diverse types of species such as jellyfishes or phytoplankton has consequences both for the maintenance of power plants and for the thermodynamics of our planet.Our approach relies on a systematic use of massive numerical simulations of the Navier-Stokes equations to generate homogeneous isotropic turbulence at high Reynolds number, and analyze in details the statistics of various types of particles such as inertial spheroids and flexible fibers. For small inertial spheroids, our numerical work shows that the translational and the rotational motion are essentially decoupled. While the translational motion can be described by the motion of a sphere with a suitably defined effective mass, the rotational dynamics displays more intricate features. This reflects in the statistics of the rotation rate and in the concentration properties. Conversely to translational motion, the rotational dynamics is therefore non-universal and depends on the specific shape of the spheroids.For small inertialess fibers, which constitute a paradigmatic example of flexible elongated particles, we find that the dynamics is most of the time closely resembling that of a stiff rod. Yet, in very rare and intermittent episodes, the fibers experience violent buckling events, which correlate to strong local compressions exerted by the local turbulent flow. Besides, detailed statistical investigations reveal that flexibility also produces misalignments of the fibers, e.g. deviations in the statistics of the orientation compared to the dynamics of a completely stiff rod. Our most salient observation is that the coupling between such flexible fibers and the turbulence can be phenomenologically modeled in terms of various activation processes, both for the buckling rate and for the misalignments statistics.We finally investigate scenarios for turbulent fragmentation of brittle fibers. To that end, we implement in our numerics two mechanisms leading to the fibers breaking in smaller pieces, either because of tensile failure or because of flexural failure. We sketch a stochastic description of such violent events that paves the way to better parametrization of turbulent-induced fragmentation of brittle material in industrial codes
Champagne, Nicolas. "Dynamique de trafic dans des réseaux microfluidiques modèles : embouteillages, chocs et avalanches". Paris 7, 2011. http://www.theses.fr/2011PA077204.
Texto completo da fonteThis thesis is devoted to the transport of particles in confined geometries. An original approach is developed, based on new home-made microfluidic tools. First, we study the traffic of particles in microfluidic obstacles networks. Due to hydrodynamics interactions between particles, we show that the traffic dynamics is a nonlinear process: the particle current does not scale with the particle density, We also establish that there exists a maximal current above which no stationary particle flow can be sustained. Then, we study the dynamic response of 1D droplet streams to finite-amplitude longitudinal perturbations. We experimentally and theoretically show that the nonlinear constitutive equation relating particle current to particle density leads to Burgers equation for the droplet stream density, Afterwards, we focus on the flow resulting from high current values in a 2D obstacles network, We observe an intermittent dynamics with avalanche phenomena. To rationalize this, we develop a numerical code close to a cellular automaton. This numerical model turns out to be effective to represent the flow of confined particles in a network of pipes. To conclude, we present the start of an experimental work, It consists in flowing a 2D crystal of solid particles. In such a configuration, hydrodynamic interactions seem to destabilize the lattice of any 2D crystals
Masmoudi, Karim. "Etude des interactions hydrodynamiques particule-particules, particules-parois par interferometrie laser". Rouen, 1998. http://www.theses.fr/1998ROUES041.
Texto completo da fonteMachicoane, Nathanaël. "Particules matérielles en écoulement turbulent. Transport, dynamique aux temps longs et transfert thermique". Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2014. http://tel.archives-ouvertes.fr/tel-01070651.
Texto completo da fonteAntoni, Mickaël. "Dynamique microscopique des plasmas : de N corps à M modes et Nq particules". Aix-Marseille 1, 1993. http://www.theses.fr/1993AIX11056.
Texto completo da fonteCisse, Mamadou. "Suspensions turbulentes de particules de tailles finies : dynamique, modification collective de l'écoulement turbulent". Thesis, Nice, 2015. http://www.theses.fr/2015NICE4014/document.
Texto completo da fonteThe numerical and experimental work of this thesis contribute to a better understanding of the dynamics of large particles in a turbulent flow. The first part allowed me to quantify their relative motion to the flow and their local influence on the surrounding flow. In a second part, I found that the collective effect of particles is to reduce the amplitude of turbulent fluctuations. In revanche, they have no influence on the fine statistical properties of the flow. Also, these measurements suggest the existence of a phase transition in the larger scales of the flow beyond a critical threshold of the number of particles
Tannous, Katia. "Contribution à l'étude hydrodynamique des lits fluidisés de grosses particules". Toulouse, INPT, 1993. http://www.theses.fr/1993INPT065G.
Texto completo da fonteBlondel, Oriane. "Dynamiques de particules sur réseaux avec contraintes cinétiques". Paris 7, 2013. http://www.theses.fr/2013PA077156.
Texto completo da fonteThis thesis is about stochastic lattice models of particle systems with Glauber dynamics and /kinetic constraints (KCSM), more specically the East and FA-1f models. These models were introduced in physics for the study of glassy systems. In this document one nds rst a summary of its contents (in French), then three introductory chapters in which I present the context of my works and show both what what my contributions add to the picture and on which notions and techniques they rely. In my presentation of KCSM, I focus on objects and results that are directly related to my research. Finally my papers are assembled in the Appendix, in some cases with extensions that were cut o for publication. The rst chapter is an introduction to KCSM. The second chapter presents non-equilibrium issues for KCSM. First I give results about out-of-equilibrium local relaxation; in the FA-1f mode it is a joint work with N. Cancrini, F. Martinelli, C. Roberto and C. Toninelli. Then I study the progression of a front in the East model and show a shape theorem as well as an ergodicity result for the process seen from the front. This result relies on quantifying the local relaxation of the process seen from the front rather than using classic sub-additivity arguments. The last chapter explores low-temperature (or high density) dynamics of KCSM. I rst recali asymptotic results about East and FA-1f spectral gaps and oer some heuristics and conjectures. I then focus on the low temperature behaviour of the diusion coecient of a tracer in a KCSM, so as to give rigorous answers to questions raised in the physics literature
Giuriato, Umberto. "Dynamique des particules actives dans les superfluides et leur interaction avec les vortex quantiques". Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4062.
Texto completo da fonteSuperfluids are inviscid flows in which vorticity is supported on filaments with quantized circulation. Such objects, known as quantum vortices, exhibit a hydrodynamical behavior. Experimentally, the dynamics of superfluids has been studied by using particles, which nowadays have become the main tool for visualizing quantum vortices. In this Thesis, we study numerically and analytically the dynamics of active and finite-size particles in superfluids. The superfluid is modeled with the Gross–Pitaevskii equation, while the particles are implemented as moving repulsive potentials coupled with the macroscopic wave function describing the superfluid. Firstly, the model is used to investigate the interaction between particles and quantum vortices at very low temperatures. This part aims to give a theoretical background to the current experiments in which macroscopic particles are used to sample superfluid vortices and quantum turbulence. Specifically, we address the following problems: the capture of a particle by a quantum vortex, the reconnections of vortex filaments and the propagation of Kelvin waves in presence trapped particles and the dynamics of particles in decaying quantum turbulence. In the last part of the manuscript, finite temperature effects are studied in the Fourier-truncated Gross–Pitaevskii model. The goal is to characterize the dynamics of impurities immersed in a thermal bath and how their presence modifies the statistical properties of the fluid. In particular, the random motion of the impurities and the temperature dependence of the friction coefficient are studied. Finally, the clustering of impurities and its effect on the phase transitions of the condensate are investigated
Schneider, Jean. "Dynamique non-newtonienne de courants de gravité chargés en particules : Étude en régime turbulent". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0308.
Texto completo da fonteGravity currents are geophysical phenomena that occur mainly in oceanic environments. These currents have been the subject of numerous studies in the absence of particles. However, their dynamics become significantly more complex when particles are in suspension. In this thesis, we aim to characterize the dynamics of these currents in the presence of particles in multiple configurations corresponding to those found in nature. The use of new measurement techniques with high spatial and temporal resolution enables us to probe the internal structure of these currents in the case of isodense flows, and to isolate the effects of high-concentration viscosity. This technique can then be used to probe the internal structure of particle-laden gravity currents according to their buoyancy properties (sedimentation, isodensity, creaming). Finally, configurations representative of those found in nature reveal dynamics far more complex than expected. The appearance of convection effects is revealed by the study of particle-laden hypopycnal currents
Aguilar, Corona Alicia. "Agitation des particules dans un lit fluidisé liquide : étude expérimentale". Toulouse, INPT, 2008. http://ethesis.inp-toulouse.fr/archive/00001206/.
Texto completo da fonteBesides its interest as an industrial application in various processes, liquid fluidization builds up an interesting test case regarding the validation of two-phase flow modelling. The lack of reliable and detailed experimental data about particle agitation in this type of flow is one important motivation to this study. In this work, the random motion of mono-dispersed particles in a liquid fluidized bed has been measured and processed from video recordings, using a refractive index matching method. 3-D trajectories of coloured particles have been collected in a wide range of solid fraction, and statistical quantities have been derived in the range of high particle Reynolds number (O(10)
Mergheni, Mohamed Ali. "Interactions particules - turbulence dans un jet axisymétrique diphasique turbulent". Rouen, 2008. http://www.theses.fr/2008ROUES067.
Texto completo da fonteGenevaz, Nicolas. "Particules greffées d'homopolymères et de copolymères pour l'élaboration de nanocomposites modèles : dispersion des particules, dynamique des chaînes greffées en relation avec les propriétés rhéologiques". Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4774.
Texto completo da fontePolymer nanocomposites interest for many years the scientific community, due in particular, to their good mechanical properties. It is established that the improvement of these properties observed in nanocomposites are mainly due to structural effects (particles dispersion) and interfacial effects (particle/matrix and particles/particles interactions). However, many experimental results are difficult to explain. In such a context, we have synthesized model nanocomposites based on silica nanoparticles grafted with polystyrene (PS) chains (or PS-b-poly(ter-butyl acrylate)) by nitroxide mediated polymerization and dispersed in a PS matrix. Then, these nanocomposites have been characterized by combining X-ray scattering and transmission electronic microscopy. By varying the length of the matrix chains, we have obtained different fillers structure going from individual nanoparticles dispersion to aggregate, up to an intermediate state (equivalent to an interconnected network for high volume fraction). Mechanical properties of these nanocomposites were studied by the mean of shear measurements at low frequency and linked to the different states of dispersion observed. Finally, we have measured local and intermediate dynamics of the grafted polymer chains by combining quasielastic neutron scattering (backscattering and spin echo) and nuclear magnetic resonance. Then, we have linked these measurements with the mechanical properties of the materials
Genevaz, Nicolas. "Particules greffées d'homopolymères et de copolymères pour l'élaboration de nanocomposites modèles : dispersion des particules, dynamique des chaînes greffées en relation avec les propriétés rhéologiques". Electronic Thesis or Diss., Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4774.
Texto completo da fontePolymer nanocomposites interest for many years the scientific community, due in particular, to their good mechanical properties. It is established that the improvement of these properties observed in nanocomposites are mainly due to structural effects (particles dispersion) and interfacial effects (particle/matrix and particles/particles interactions). However, many experimental results are difficult to explain. In such a context, we have synthesized model nanocomposites based on silica nanoparticles grafted with polystyrene (PS) chains (or PS-b-poly(ter-butyl acrylate)) by nitroxide mediated polymerization and dispersed in a PS matrix. Then, these nanocomposites have been characterized by combining X-ray scattering and transmission electronic microscopy. By varying the length of the matrix chains, we have obtained different fillers structure going from individual nanoparticles dispersion to aggregate, up to an intermediate state (equivalent to an interconnected network for high volume fraction). Mechanical properties of these nanocomposites were studied by the mean of shear measurements at low frequency and linked to the different states of dispersion observed. Finally, we have measured local and intermediate dynamics of the grafted polymer chains by combining quasielastic neutron scattering (backscattering and spin echo) and nuclear magnetic resonance. Then, we have linked these measurements with the mechanical properties of the materials
Guerrault, Xavier. "Simulation moléculaire de fondus de polymères par la méthode de la "Dynamique des particules dissipatives"". Paris 11, 2004. http://www.theses.fr/2004PA112217.
Texto completo da fonteThis work deals with the modelisation and the simulation of Polyethylene (PE) and 1,4cis-Polybutadiene (cis-PB) melts at mesoscale using the “Dissipative Particle Dynamics” (DPD) method. Polymers are represented as chains of beads each one regrouping (called the coarse-graining level) monomers and subjected to the conservative, dissipative, and random DPD forces. First, a set of parameters for the PE and cis-PB effective conservative interactions is established for several from microscopic Monte Carlo simulations and using the mean-force potential concept. Scaling laws of the Rouse regime are recovered for all chain lengths. Results for the structural quantities are in good agreement with experimental data and detailed microscopic simulations. It is even observed a global (independent of the coarse-graining level) scaling law for the evolution of the root mean square end to end distance with the length of the underlying microscopic chain. Then, the parameters of the dissipative force are adjusted for PE, enabling the comparison between dynamical properties at micro and mesoscale. No transition from the Rouse to reptation regime, related to the existence of entanglements, is observed here. This is due to the fact that the potentials used are (and have to be) too weakly repulsive. To overcome this problem, a “non-crossing” algorithm is implemented to artificially re-introduce entanglements, leading for the moment only, to a slowing down of the dynamics
Tran, Dinh Trinh. "Identification des sources et modélisation du comportement dynamique des particules dans l’air intérieur des écoles". Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10015/document.
Texto completo da fonteDuring this thesis, we chemically characterized (metals, EC, OC) then studied the sources and the fate of airborne particles (PM10, PM2,5, PM1) in indoor air. Another part of this work concerns the modelization of their behavior in class-rooms of primary schools in the Nord Pas de Calais region. These PM10 values largely and almost systematically exceed (average value for eight schools: 97 ± 28μg/m3) the daily limit values (50μg/m3) for indoor air (WHO and ANSES recommendations). The only elements Al, Ba, Ca and Fe clearly associated to an indoor source are linked to the use of chalk. Although there is a significant amount of particles of outdoor origins found in class-rooms (such as traffic, industrial or natural sources), pupils’ physical activities represent the major source of airborne PM10 in indoor air. The resuspension phenomenon doesn’t influence significantly the elemental (major and traces elements) distribution of the indoor PM10.The modelization of the evolution of indoor PM10 is clearly influenced by the activities of the pupils in class-rooms, requiring taking into account the resuspension phenomena. In addition, the behavior of particles is associated to their size distribution as well as the intrinsic characteristics of the building envelope which control the indoor-outdoor air exchange.The deterministic model developed in this work will allow easily simulating the evolution of particle concentrations according to their size distribution in class-rooms
Vallée, Robin. "Suspensions de particules inertielles dans des écoulements turbulents". Thesis, Université Côte d'Azur, 2021. http://www.theses.fr/2021COAZ4025.
Texto completo da fonteThis thesis focuses on the dynamics of inertial particles suspended in turbulent fluid flows that are governed by the incompressible Navier-Stokes equations. Understanding the transport of these particles is important in a number of applications, such as the growth of planetesimals by accretion, the evolution of plankton in the oceans, the growth of ice crystals in clouds or the sedimentation of impurities in pipes. Despite the presence of these particles in many industrial or natural processes, their dynamics remain a poorly understood subject. The aim of this thesis is to contribute to a better understanding of certain aspects involving the transport of inertial particles in turbulent flows, using in particular the results of direct numerical simulations. It is divided into four chapters. The first is devoted to an introduction to the motivations, the numerical methods used, as well as to a review of the results already known on this topic. The second chapter deals with the generalization of the phenomenon of turbophoresis in the case of homogeneous and isotropic flows, and therefore completes an approach mainly used for inhomogeneous flows. In particular, it is shown that despite their uniform mean, local turbulent fluctuations lead to inhomogeneities in the distribution of particles at inertial scales. Then, the third chapter is devoted to the accretion of inertial particles by a sphere embedded in a mean flow. First, it is shown that inelastic bounces of point particles on the surface of the sphere are not sufficient to lead to inelastic collapse, when they are subjected only to a viscous drag force. Secondly, the study of small particles subjected to the force of gravity, shows non-trivial accretion efficiencies, with in particular collisions observed at the back of the collector. Finally, the last chapter deals with particles of finite sizes suspended in a turbulent channel flow and subject to their viscous drag force and to a lubricating force close to the walls. A statistical study of the distribution of particles and of their collisions with the walls then improves the understanding of deposition mechanisms
Devals, Christophe. "Contribution à l'étude de l'interaction ondes de choc - particules". École nationale supérieure de l'aéronautique et de l'espace (Toulouse ; 1972-2007), 2002. http://www.theses.fr/2002ESAE0021.
Texto completo da fonteThis study takes place within the context of solid propulsion rocket infrared signature in supersonic flight. The aim of this present work is to study the two-phase flow exhaust plume jet at the exit of the nozzle
Condoret, Jean-Stéphane. "Etude des transferts en écoulement pulsé dans un lit de particules". Toulouse, INPT, 1987. http://www.theses.fr/1987INPT011G.
Texto completo da fonteDjeddou, Mokhtar. "Étude de la dynamique des polluants particulaires dans un habitacle automobile". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0231.
Texto completo da fonteAir pollution, especially that caused by fine and ultrafine particles, has significant deleterious effects on human health. Several studies have established a direct link between exposure to particulate pollution and various respiratory and cardiovascular diseases. Within vehicles, the threat is even more concerning due to the significant concentrations of particulate pollutants recorded. Therefore, improving air quality inside vehicle cabins is now a major priority for automotive manufacturers. In this context, this study aims to understand the interior environment of vehicles by characterizing the spatial distribution of pollutants, particularly fine and ultrafine particles, as a function of their size and parameters such as flow topology and turbulence level. This knowledge will be crucial for targeting localized air purification solutions, optimizing the placement of the micro-sensors that will equip future vehicles, and providing solutions for the more effective management of filtration systems as a function of the distribution and concentrations of these particles in the car cabin. First, special attention was devoted to modeling the single-phase flow. Two numerical modeling approaches have been adopted: the RANS (Reynolds Averaged Navier-Stokes) approach, based on solving the mean flow fields of the Navier-Stokes equations, and the LES (Large Eddy Simulation) approach, which involves solving the large structures containing the major part of the kinetic energy and modeling the contributions of the smaller scales. In the case of the RANS approach, various closure models, of first- and second-order, have been tested and compared. Furthermore, the turbulence structure of the flow inside the car cabin has been analyzed using Lumley's Anisotropy Invariant Mapping method (AIM). Finally, to validate the results of the numerical models, a velocity field measurement campaign, based on hot-wire anemometry technique, was conducted inside the cabin of an SUV-type car. Next, the dynamics of particulate pollutants in the car cabin was studied using the Diffusion-Inertia Model (DIM). This Eulerian model of inertial particle diffusion takes into account various transport mechanisms, including transport by the mean field, the effect of volume forces (i.e., gravity), particle deviation from fluid streamline (centrifugal effects), Brownian and turbulent diffusion, and turbophoresis or transport by turbulent kinetic energy gradients. The model was first validated on standard configurations such as dispersion in small-scale ventilated enclosures, deposition in 90° circular bends, and particle transport in a round jet flow. The model was then applied to simulate particle transport inside a large-scale vehicle. The influence of particle size on internal concentration fields was first analyzed. Then, the influence of passenger presence was studied. Finally, a particle concentration measurement campaign was conducted in the cabin to assess the relevance of the two-phase model. This study has led to the development of a complete model for simulating the dispersion of particulate pollutants inside a car cabin based on ventilation conditions and particle characteristics
Thill, Antoine. "Agrégation des particules : structure, dynamique et simulation : application au cas d'un écoulement stratifié : l'estuaire du Rhône". Phd thesis, Aix-Marseille 3, 1999. http://tel.archives-ouvertes.fr/tel-00109390.
Texto completo da fonteEn effet, afin de mener à bien cette étude, il a fallu développer de façon préliminaire différents outils. On a ainsi mis au point deux nouvelles méthodes de mesure expérimentale de la structure des agrégats qui échappent aux techniques existantes. Ces méthodes permettent, outre une meilleure connaissance du système, de développer et de valider un nouveau modèle de la cinétique de croissance des agrégats. Ce modèle numérique prend en compte la dimension fractale des agrégats ainsi que sa variabilité. Il est validé par confrontation à des données issues de la bibliographie et l'expériences.
Une étude de terrain dans l'estuaire du grand Rhône est menée dans des conditions hydrodynamiques contrastées (étiage, débit moyen et crue). Elle a permis d'obtenir, pour la première fois, une série de mesures de tailles de particules tout au long de la zone de mélange. Il est établi que les particules les plus grosses (supérieures à 5 microns) présentent une évolution contrôlée par la dilution, la sédimentation et
éventuellement la remise en suspension. Par contre, les particules plus petites (2 à 5 microns) montrent une augmentation de leur concentration le long de la zone de mélange. Dans les premiers temps du mélange, cette augmentation est liée à la fragmentation d'agrégats. Il est possible de montrer ensuite i) que l'agrégation des colloïdes ne peut expliquer cette augmentation que si ceux ci ne réagissent pas avec les fractions de tailles supérieures et présentent une réactivité très supérieure à la réactivité moyenne (alpha : 0.009) et ii) que la production primaire est un mécanisme probable pour expliquer cette augmentation.
CONIN, LAURENT. "Etude de la dynamique des collisions pb + pb a 158 agev / c par interferometrie de particules". Paris 11, 2001. http://www.theses.fr/2001PA112098.
Texto completo da fonteChu, Tien Dat. "Dynamique sédimentaire en zone côtière dans les cas de sédiments multi-classes". Le Havre, 2012. http://www.theses.fr/2012LEHA0009.
Texto completo da fonteThe sediment dynamics in coastal zone results from very complex interaction between the hydrodynamic forcing (wave, current, tide) and marine sediments which generally exhibit different sizes, densities and shapes. This interaction often leads to the formation of ripples on the bed and the phenomenon of sediment-sorting. The ripples and the sediment segregation significantly influence the sediment transport by changing the bottom roughness, the structure of the bed boundary layer and the dissipation of the hydrodynamic forcing. This thesis focuses on the sediment dynamics in coastal zone in the case of heterogeneous sediments in size and density. The objective of this work is to provide a contribution to the understanding and the modeling of the process which control the sediment transport and sediment-sorting under the action of waves. The experimental tests were conducted in wave flume and a theoretical study was made
Cardot, Jérôme. "Adhésion et détachement de particules en contact avec une surface sous écoulement d'air : application aux milieux fibreux". Toulouse, INPT, 2000. http://www.theses.fr/2000INPT024H.
Texto completo da fonteJana, Arindam. "Collage et adhérence de particules dans le domaine de la sous-monocouche". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0074/document.
Texto completo da fonteDuring plasma assisted deposition, properties of the coating substrate interface depend on the first atomic layer of the deposit, or the atoms that first start to cover the surface. Therefore the good knowledge of the sticking coefficient and the reorganization of the surface following particle impact is an essential issue to achieve the description of the behavior of the processed surface and, therefore, its expected properties. Consequently, we investigated the interaction between incoming particles (C, Ti, W) and a silicon surface by using an approach combining molecular dynamic simulations and experiments. Various initial conditions were studied, energy, fluence and incidence angle of the incoming particles. An important part of this work has consisted in adapting the molecular dynamic codes (using reactive force fields) to the investigated systems. Meanwhile, experimental procedure specifically devoted to the use of the Storing Matter facility was also developed. Results show that the sticking coefficient (SC) value is in the range [0.7 – 1] irrespectively of the incoming species; in the case of W, almost all atoms stick on the surface (SC~~1). Besides the determination of sticking coefficient, the surface modification resulting from the particles impingement were determined for various initial conditions (energy, fluence, angle) in terms of implantation and displacement of the incoming species, and surface sputtering as well
Sardoy, Nicolas. "Transport et combustion de particules générées par un feu de végétation". Phd thesis, Université de Provence - Aix-Marseille I, 2007. http://tel.archives-ouvertes.fr/tel-00289521.
Texto completo da fonteLongaretti, Pierre-Yves. "Dynamique des anneaux de Saturne : ondes de densité et distribution en taille des particules dans les anneaux". Phd thesis, Grenoble 1, 1987. http://tel.archives-ouvertes.fr/tel-00725111.
Texto completo da fonteAtwi, Ali. "Modélisation théorique et numérique de la dynamique de particules macromoléculaires en écoulement dans des systèmes méso-poreux". Phd thesis, Université du Maine, 2012. http://tel.archives-ouvertes.fr/tel-00699779.
Texto completo da fonteFlavien, Lahmar. "Simulation moléculaire de fondus de polymères et d'élastomères par la méthode de la "Dynamique des Particules Dissipatives"". Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00408096.
Texto completo da fonte