Tesi sul tema "Milieux granulaires – Dynamique des fluides"
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Abriak, Nor-Edine. "Ecoulement d'un matériau granulaire à travers un orifice effet de paroi". Lille 1, 1991. http://www.theses.fr/1991LIL10122.
Khati, Salah. "Comportement des matériaux : étude micro-macro du frottement et de la dilatance". Lille 1, 1996. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1996/50376-1996-77.pdf.
Félix, Gwenaëlle. "Écoulements de milieux granulaires en tambour tournant : étude de quelques transitions de régime : application à la ségrégation". Vandoeuvre-les-Nancy, INPL, 2002. http://www.theses.fr/2002INPL080N.
Djouwe, Meffeja Merline Flore. "Simulation et modélisation de milieux granulaire confinés". Rennes 1, 2012. http://www.theses.fr/2012REN1S005.
Because of their industrial and geophysical applications, granular flows have a prominent place in our environment. In this thesis, we study these flows by numerical simulation of type "discrete elements" (where the grains are treated explicitly) and of type "continuous medium" (where the granular material behaves as an effective medium obeying a given rheology). We first studied the granular flows by the "discrete elements" method in silo geometries. By changing the micro-mechanical properties of the grains (restitution and friction) we showed that they had a significant influence on the flow discharge. A detailed study of the behavior of grains has shown that this influence comes from a variation of the packing fraction at the outlet of the silo, the grains velocity experiencing very little change. Although models such as "discrete elements" provide access to all the individual properties of the grains, they have one major drawback : the computation time is very important that prohibits the modeling of geophysical and industrial situations. To overcome this problem, we used the "continuous medium" approach, which consider that the granular medium studied follows a rheology recently proposed in the literature. After discussing the numerical implementation, we have studied this rheology for steady and fully developed flows with a semi-analytical method in two configurations: a shear cell and a channel. This allowed us to highlight the differences between a granular medium and a Newtonian fluid
Chrząszcz, Kamil. "Ondes dans les milieux granulaires : de l’échelle microscopique à l’échelle macroscopique". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC064/document.
This thesis deals with the study of mechanical wave propagation in dry or wet granular media, with the aim of relating the phenomena at the microscopic scale (particles dynamics, interaction potentials between grains, rheology of the interstitial fluid) to the features at the macroscopic scale (dispersion relation, wave speed and attenuation in the long wavelength approximation). The systems under study are either large one-dimensional granular media, as the analogs of the paths of the most compressed grains (the force chains) in real granular packings, or the real granular media themselves. In a first place, we study experimentally the wave transmission through alignments of dry centimetric spheres, which we model via the Hertz potential. We show that the elasto-frictional coupling between the grains and a substrate (the spheres’ support) induces an on-site elastic potential, which in turn induces a band gap at zero frequency in the transfer function. In a second place, we show that the presence of an infinitesimal amount of viscous fluid at the contact between every particle induces an elasto-hydrodynamic (EHD) interaction. The later affects the attenuation of waves in addition to a significant increase of the wave speed, which in this case both non-trivially depend on the elasticity of the particles, on the viscosity of the fluid and on the frequency. In a third place, we check the reliability of our analysis to describe ultrasonic wave propagation in real granular materials such as dry or wet sand; our particles are here millimetric spheres. In the dry configuration, our results are consistent with an effective medium theory (EMT) which relies on the Hertz-Mindlin interaction in the long wavelength approximation. In the wet configuration, the EMT model combined with an EHD mechanism fairly reproduces our preliminary observations
Sierra, Christophe. "Instabilité en fluidisation gaz-solide : dynamique des lits denses et influence des conditions aux limites". Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX11064.
Mutabaruka, Patrick. "Modélisation numérique des milieux granulaires immergés : initiation et propagation des avalanches dans un fluide". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-00984870.
Jop, Pierre. "Ecoulements granulaires sur fond meuble". Phd thesis, Université de Provence - Aix-Marseille I, 2006. http://tel.archives-ouvertes.fr/tel-00106185.
Ce travail s'articule principalement en trois parties. Premièrement, dans le but de fournir une description détaillée des écoulements sur tas, une étude expérimentale systématique des écoulements stationnaires a été menée dans un canal. Nous avons ainsi pu mettre en évidence l'importance des parois latérales du système dans le cadre des écoulements à la surface d'un tas : les propriétés de l'écoulement sont complètement contrôlé par la largeur du canal. Ce constat nous a ensuite conduit à la proposition d'une modélisation fondée sur une rhéologie récemment développée.
Cette rhéologie a été ensuite étendue à trois dimensions et appliquée à notre configuration. Des simulations numériques permettent de reproduire correctement les propriétés des écoulements stationnaires. Nous avons enfin étudié un phénomène transitoire particulier afin de comprendre la manière dont l'épaisseur coulante évolue. Malgré la présence de certaines limitations, ce travail montre qu'une description locale des écoulements granulaire est appropriée et que la rhéologie proposée ouvre la voie à des modélisations plus complètes des écoulements granulaires denses.
Lecointre, Pierre. "A la recherche de la texture hydrophobe, et quelques effets collectifs dans les milieux granulaires et en économie". Thesis, Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAX009.
Fog or hot water can destroy the superhydrophobic properties of a textured surface owing to the condensation inside the texture. However, it was recently shown that such surfaces covered with cones at a scale of hundred nanometers could resist fog: condensed droplets can be ejected during their coalescence. We first experimentally show by electronic microscopy that a conical texture enables water drops to remain in a “fakir state”, even at a very small scale. We then studied different families of cone-textured surfaces by varying the spacing and the texture height. At the nanoscale, we showed that the texture size has a low influence on the antifogging efficiency whose limits rather lie in the water properties themselves, especially its viscosity. At the microscale, we described new situations where spontaneous ejection of condensed drops occurs despite a local trapping of water. We also studied the trajectory of expelled drops on such surfaces and confirmed that viscous effects play a major role in their ballistics. Finally, we focused on the ability of superhydropho- bic surfaces to repel hot water, a challenging situation for which we identified two independent recipes. In the second part of the thesis, we studied the ability of wetted fibers to capture dust. We showed that the quantities of captured particles is only influenced by the quantity of oil deposited on the fiber and not by its configuration (film or drop) on the fiber, unlike the growth kinetics of the aggregate where large differences are observed between the two configurations. The last part of the thesis focused on the Slutsky equation, a classical equation encountered in microeconomics. We described how the Slutsky matrix is modified when challenging classical economics hypotheses such as irrationality, interactions between goods or agents’ heterogeneity, and how it exhibits surprising features not predicted by consumer choice theory. The three parts can be addressed independently
Pascot, Arthur. "Rhéologie et propriétés de vidange de milieux granulaires modèles : application à l’écoulement en silo". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0156.
The discharge of grain in a silo is a common application in industry, but this typical granular flow is still not fully understood. Without a real fundamental understanding, the optimization of this application is done by empirical means, for example by applying vibrations to improve the discharge. Understanding the behaviour of this flow, and in particular the link between the apparent flow rate and the particle reorganization dynamics, would therefore allow a theoretical breakthrough and would open up practical ways of optimizing these flows in an industrial configuration. In this thesis, we study the discharge of model granular matter (monodisperse spherical beads) in a quasi-2D silo under the influence of mechanical vibrations. Experimental measurements and discrete element simulations (DEM) are performed to determine the effect of the geometry, particle properties and vibration characteristics. We evidence that vibrations make appear two distinct regimes, governed by the Froude number Fr and the relative frequency Ω of the vibrations. In the first regime, a decreased flow rate is observed when increasing the vibration intensity. This behavior is explained by the setting in motion, due to the vibration, of areas previously at rest and a higher energy dissipation. In the second regime, an increased flow rate is observed when increasing the vibration intensity. We find this behavior comes from the intermittent nature of the flow, with bursts of flow rate created by the propagation of shock waves all along the silo. As a first step, we propose for each regime an empirical law for the flow rate depending on the different parameters. Then, we studied the flow at the local scale in order to relate the apparent flow rate to local particle dynamics through flow rheology
Doppler, Delphine. "Stabilité et dynamique de pentes granulaires sous-marines". Phd thesis, Université Paris Sud - Paris XI, 2005. http://tel.archives-ouvertes.fr/tel-00109458.
Une première étude est consacrée aux seuils de mise en mouvement des particules. Deux modèles simples prenant en compte la gravité, la friction entre particules et le cisaillement du fluide, permettent de retrouver l'influence de la vitesse de l'écoulement d'eau et de la pente du lit sur les seuils de transport par érosion et par avalanche.
Le régime d'écoulements gravitaires est ensuite exploré pour des pentes au-delà de l'angle maximal de stabilité. Les mesures d'évolution de la pente du tas et du débit de particules (par PIV) montrent que l'avalanche atteint rapidement un régime quasi-stationnaire. La vitesse des grains dépend uniquement de la pente du tas, dans une relation quantitativement prédite par un modèle adapté des développements récents de modélisation de la rhéologie des granulaires.
Dans une troisième partie on s'intéresse à la déformation de l'interface granulaire dans un régime particulier. La formation de rides à tourbillon est observée à la surface de l'avalanche, lorsqu'on applique un écoulement d'eau qui tend à transporter les particules dans la direction opposée. Après une phase initiale de croissance exponentielle, l'amplitude des rides sature. La zone de recirculation à l'arrière de la ride semble contrôler la forme des structures tandis que la quantité de matière transportable par l'avalanche semble déterminer leur amplitude.
Saingier, Guillaume. "Mécanismes et dynamiques d’interactions entre grains et liquide : du matériau granulaire sec au mélange saturé". Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS230.
Granular materials are ubiquitous, both in nature and in industry or in our daily life. Blending grains and liquid is a basic operation at the origin of many industrial processes. Nevertheless, the understanding and the modeling of the mechanisms of exchanges of liquid and grains, implied in the mixing process, remain largely unknown. In this PhD, we propose to investigate the mechanisms of interactions between a granular material containing a variable quantity of liquid and flowing dry grains. Depending on the amount of liquid, the wet granular phase can be eroded by the granular flow, or flowing grains can be captured by granular accretion or the liquid can be transported from the wet to the dry phase by impregnation. First, we focus on the mechanisms and the dynamics of granular accretion observed after the impact of a dilute granular jet on a wet granular substrate. We highlight the role of liquid interfaces on the growth dynamics and the sources of energy dissipations implied in the capture. Then, using an experiment of accretion with a dense and shear granular flow, we study the influence of the flow properties on the dynamics of capture and we propose a general accretion law. The rotating drum configuration with an isolated aggregate in a granular flow allows us to extend our investigation with the situation of unsaturated granular materials growing by accretion before being eroded. In the second part of the PhD, we study the impregnation in a dense granular jet penetrating into a liquid bath. By modeling the grains intrusion as the impregnation of a porous medium, we highlight the link between the shape of the front profile and the immersion speed. We also characterize the influence of the physico-chemical properties of the grains. This work constitutes a first step in the understanding of local phenomena implied in granular blending processes and the transition from dry to wet granular media
Benmansour, Leïla. "Écoulement gravitaire dans un silo parallélépipédique". Compiègne, 1996. http://www.theses.fr/1996COMPD941.
Abbas, Micheline. "Auto-diffusion de particules dans un écoulement cisaillé : des interactions hydrodynamiques aux effets collisionnels". Toulouse, INPT, 2008. http://ethesis.inp-toulouse.fr/archive/00000622/.
Lagrangian simulations are used to study the rheophysics of sheared suspensions of spherical particles. The effects of the fluid inertia, the Brownian diffusion and the gravity are neglected. Depending on the particle inertia characterized by the Stokes number, the suspensions are divided into two major classes. The limit of vanishingly small Stokes numbers corresponds to solid particles suspended in a very viscous fluid. The "Force Coupling Method" is used to model the direct hydrodynamic interactions controlling the dynamics of these monodisperse suspensions. This method is based on a finite multipole expansion of the velocity field perturbation induced by each particle. The motion of all the suspension particles is simultaneously coupled through the direct solution of the Stokes equations written for the carrying fluid flow. The macroscopic evolution is studied while the solid volume fraction is increased from low to moderately concentrated [φ=1-20%]. The results (velocity fluctuation, self-diffusion, velocity auto-correlation and spatial distribution of pairs. . . ) are in agreement with several former studies of the literature. We showed that the particle agitation is enhanced by increasing the concentration and leads to a diffusive behavior of the suspension. The agitation level and the characteristic diffusion time are increasing as many-body hydrodynamic interactions control the suspension dynamics. The accuracy of the method is improved by calculating the exact lubrication forces for particle pairs near contact. Hence, this allows to simulate larger suspension concentrations (up to 35%), and to quantify the effective viscosity in this regime. The model is extended to the bidisperse suspension configurations. The dependence of the statistical quantities (of both species) on the size ratio and concentration ratio is discussed for a fixed total volume fraction. For a constant concentration ratio, we obtained that an increase of the size ratio enhances (resp. Reduces) the fluctuation level of the small (resp. Large) particles. The increase large particle number induces a significant enhancement of the fluctuations and self-diffusion of both species. The suspensions characterized by moderate to high Stokes numbers are generally of gas-solid type. A hard-sphere collision model coupled with the particle Lagrangian tracking is used to simulate the suspension dynamics. The particle motion is controlled by only the drag force and particle collisions. The simulations show that the suspension properties depend strongly on the particle inertia and concentration. Increasing the Stokes number from 1 to 10 induces an enhancement of the suspension agitation by three orders of magnitude, and an evolution of the velocity distribution function from a highly peaked (close to the Dirac delta function) to a Maxwellian shape. The numerical results are compared to the predictions of two theoretical models based on the kinetic theory of granular flows adapted to moderate inertia regimes. The velocity distribution used for weakly (resp. Highly) agitated suspensions is the Dirac delta (resp. Deviated Maxwellian) function. A new prediction of the Lagrangian self-diffusion tensor is proposed and validated by the simulations results. The diffusion coefficients and solid phase viscosity are compared to the classical models used in engineering applications. The inelasticity effect on the statistical quantities is discussed as well. The conclusion of the manuscript proposes a unified approach of all the results related to the evolution of the effective viscosity in the bulk. A modification of the Force Coupling Method is proposed to properly simulate the particle inertia and hydrodynamic effects
Abbas, Micheline Climent Éric Simonin Olivier. "Auto-diffusion de particules dans un écoulement cisaillé des interactions hydrodynamiques aux effets collisionnels /". Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000622.
Obando, Vallejos Benjamin. "Mathematical models for the study of granular fluids". Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0274.
This Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely : • In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids : the viscous nature of the interstitial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. • In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. • In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface
Lecomte, Charles-Edouard. "Instabilités dans un milieu granulaire : tôle ondulée sur un lit de sable, et ségrégation au sein des astéroïdes lâches". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN024/document.
This thesis, consisting of two parts, is focusing on instabilities into a granular assembly.The first part deals with washboard road instability, which is the growth of a ripplepattern on a track subjected to repeated passages of vehicles. Our experimental work aswell as soft spheres numerical simulations provide us a better understanding of this phenomenon.In the case of a rigid wheel dragged at constant velocity, we quantitatively studiedthe impact of the cohesion into the granular media on the main features of the instability :critical velocity, wavelength and growth rates. Finally, we have begun preliminary studieson a yield stress fluid, namely a carbopol microgel.The second part is devoted to the granular segregation in asteroids. Several keys showthat a significant part of them are rubble-piles, without internal cohesion and held togetherby their weak self-gravity. The distribution of grains is heterogeneous : while some regionsconsist in fine sand or powder, large boulders seem to accumulate in other parts. Wenumerically simulated a granular pile and subjected it to repeated quakes : we managedto reproduce segregation. We studied the influence of physical and numerical parameterson the segregation level and the dynamics of the phenomenon. We also investigate variouscauses of the segregation : granular convection, kinetic sieving, depletion pressure, etc.Finally, we highlighted an azimuthal segregation which can explain observations duringspatial missions
Larrieu, Emeline. "Dynamique d'un lit granulaire sous écoulement visqueux oscillant". Toulouse 3, 2006. http://www.theses.fr/2006TOU30219.
The interaction between a granular bed and a viscous oscillating Couette flow is studied. The Shields number is close to 1 and the particle Reynolds number small relative to 1. The injection an ink streak above the ripples shows the existence of a steady streaming directed from troughs to crests. Theoretical calculations including lagrangian deformation of the streak recover the experimental results. Growth of the ripples is then studied. The initial wavelength seems independent of Shields number and is quite scattered. A latency period exists before the onset of instability, during which bed compaction is observed, whereas decompaction occurs during ripple growth. Macroscopic and grain-size behaviours are strongly related. Decompaction seems localised on ripples'crests. An independant part deals with the collapse of a dry granular column. A shallow-water model combined with progressive mass addition enables to reproduce numerically experimental scaling laws for runout distance and height
Badr, Sarah. "Erosion d'un milieu granulaire par un jet". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112349/document.
The present thesis consists in the experimental study of the erosion of a horizontal granular bed by a vertical jet. In a first part we study in details the erosion threshold. With the injector fixed at a given distance from the granular surface, the mean jet velocity is gradually increased until the displacement of first grains at the bed surface. Depending on the jet-bed distance, different jet flow regimes are observed, from laminar to turbulent. Using self-similar jet models in either laminar or turbulent regimes, which predict the axial velocity decay as a function of the distance from a flow point source called virtual origin, the local velocity at the bed position is estimated, allowing us to show that the local erosion mechanism described by the Shields number is inertial and independent of the jet regime. In a second part, we study the shape of craters formed above erosion threshold. Increasing the Shields number, the crater goes from a shape entirely parabolic to a more complex one with an invariant parabolic region close to the jet axis and a constant avalanching slope further on the side. We show that the bed thickness has no influence on the crater characteristics as long as the jet does not reach the bottom wall. When it does, we observe a third shape for the crater composed of a central flat region without any grains connected to the avalanching crown on the side by a small parabolic crown. We show the crater characteristics are governed by the jet-bed distance and that it is necessary to take into account the difference between the Shields number and its threshold value in this distance analysis
de, Moraes Franklin Erick. "Dynamique de dunes isolées dans un écoulement cisaillé". Toulouse 3, 2008. http://thesesups.ups-tlse.fr/302/.
The transport of solid particles entrained by a fluid flow as bed-load is frequently found in nature and in industrial environments. If bed-load takes place over a non-erodible ground, and if the particles flow rate is small enough and the fluid flow one-directional, an initial thin continuous layer of particles becomes discontinuous and composed of isolated dunes with a crescentic shape: the barchans. We present here an experimental study concerning barchans dynamics when submitted to a rectangular closed-conduit turbulent fluid flow. On the one hand, we investigate the migration of barchan dunes. On the other hand, we investigate the fluid flow perturbation caused by the dune, in particular the shear stress acting on its surface
Seguin, Antoine. "De la pénétration en milieu granulaire". Phd thesis, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00727081.
Rondon, Loic. "Effondrement granulaire : couplages fluide-grains". Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10209/document.
Nous étudions expérimentalement l'effondrement d'une colonne granulaire dans un liquide visqueux. Contrairement au cas sec, la morphologie des dépôts n'est principalement plus contrôlée par le rapport d'aspect initial du tas mais par la fraction volumique initiale de la masse granulaire. Deux régimes différents sont identifiés selon l'empilement initial. L'empilement lâche donne lieu à des dépôts minces et longs et la dynamique est rapide. Une surpression du liquide est mesurée sous de la colonne. Pour l'empilement dense, l'étalement final est deux fois moindre, le mouvement est lent et une dépression interstitielle est mesurée. Ces observations suggèrent que la dynamique de l'effondrement granulaire dans un fluide est fortement affectée par le comportement de la dilatance du milieu granulaire.Nous développons ensuite un modèle théorique basé sur des équations diphasiques moyennées dans l’épaisseur prenant en compte les mécanismes de dilatance. L’étude dimensionnelle de notre modèle permet de montrer que l’effondrement d’une colonne est contrôlé par trois paramètres sans dimension : le rapport d’aspect de la colonne, la fraction volumique initiale, et le nombre de grains dans l’épaisseur. On montre également que le temps caractéristique met en compétition le frottement visqueux et la gravité.De ce modèle, nous développons un algorithme de résolution lagrangien. Cette approche, grossière mais robuste, permet d’implanter s sans trop de difficulté. Le code est validé sur des configurations simples sur plan incliné avant de simuler l’effondrement de colonnes granulaires immergées dans la même gamme de paramètres que nos expériences
Deseigne, Julien. "Système expérimental modèle d'un fluide actif polaire". Phd thesis, Université Paris-Diderot - Paris VII, 2010. http://tel.archives-ouvertes.fr/tel-00567513.
Serres, Marion. "Étude hydrodynamique d'un écoulement gaz-liquide dans un milieu poreux confiné". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN018/document.
This thesis focuses on gas-liquid flow in porous media, a common problem encountered in various domains from fundamental physics to applied chemical engineering. We have characterized the hydrodynamic regimes based on two different experimental devices geometry: a millichannel (1D flow) and a Hele-Shaw cell (2D flow). The originality of this work is to analyze the influence of the porous medium (monodisperse micro-packed beds or open cell solid foams), confinement (1D/2D) and gravity by coupling global and local analysis from either chemical engineering or fundamental physics community. On the one hand, a global analysis made it possible to quantify pressure drops, residence time distributions (RTD) based on fluorescent dye transport and gas-liquid mass transfer on the 1D device. On the other hand, a local analysis of the liquid fraction and the spatio-temporal evolution of its frequency pointed out the existence of two hydrodynamic regimes: a Taylor-like regime in which the characteristics of the periodic flow upstream are conserved in the porous medium and a modulated regime characterized by the flow disorganization at the porous medium entrance. A phenomenological model is developed based on bubbles propagation inside the medium and reproduces well both regimes. These two analyses are finally coupled to study multiphase flows inside the Hele-Shaw cell. The effects of gravity and confinement are discussed
Zou, Zhenhai. "Etude de l'éjection de grains hors d'un cylindre pressurisé". Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0412.
We consider a hypothetical scenario of reactivity initiated accident in a nuclear power plant. The violence of the so-called fuel-coolant interaction phenomena depends strongly on the flow rate of particles out of the gas pressurized rod. The aim of this thesis was to study how this discharge rate is driven by the internal geometry and the pressurized gas. We focused firstly on the discharge of a rectangular silo with an inclined bottom. For a small inclination angle, the granular flow orientation is controlled by the wall friction, whereas a large inclination angle fully determines this orientation. Secondly, we focused on two configurations with pressurized gas : a case with constant gas overpressure at the top of the silo and a more transient case for which an initial larger overpressure initiates the rupture of an orifice. The granular flow rate increases significantly with the gas flow, especially for the finer particles and the large overpressures. In both cases, the flow rate scales with a modified Beverloo law where the gas pressure gradient near the outlet acts as an additional driving force. The pressure gradient is well described by a Forchheimer resistance law through the granular medium. We therefore propose a quasi-steady model for the transient description of the granular flow rate. The two configurations were successfully reproduced by numerical simulations based on a continuum multiphase model. For the larger flow rates, instabilities of the granular jet were found to be initiated by pressure oscillations in the outlet region. The presence of water surrounding the silo only acts through an additional hydrostatic pressure effect
Haffner, Benjamin. "Stabilité des suspensions fortement aérées". Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1095/document.
We study the drainage of granular suspensions foams. Our control parameters are the gas fraction, the bubble size, the particles size and the interstitial particle fraction. First, we measure the proportion of liquid and particles retained in the foam network as function of the above mentioned parameters. These measurements are performed when the drainage is over, they are essential for the description of drainage velocity. We show that certain combinations of our study parameters lead to the jamming of the three-phase system : gas, liquid, solid. Secondly, we highlight different regimes of drainage velocity, we show that is controlled by two parameters : (i) lambda, the ratio of the particle size and constriction size, (ii) the fraction of particles in the interstitial network : phi. The key to understand these regimes is the trapping of particles in the foam : (i) the jamming, which may occur for surprisingly low fractions due to the geometry of the pore network, (ii) the particles captured by the foam network when they become larger than the constrictions network. Finally, larger particles excluded from the network increase the drainage velocity, as a consequence the minimum for the velocity corresponds to the individual capture. The granular fraction of the suspension in the foam network is the other key parameter. Especially, the drainage can be stopped for sufficiently high fractions for certain values of lambda. This work offers promising outlook for the stability of three-phase materials
Hamidouche, Souria. "Étude expérimentale et numérique de l'écoulement autour d'une ride isolée". Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2311/document.
The aim of this study is to examine the processes leading to development a bed river, estuary or coastal environments morphology. The ability to investigate the complex nature of the interaction between fluids and sediments mechanisms and its role in bed transport and river stability is important to understand river evolution. Dunes or ripples are in frequent interaction with the bed. Hence, the topology of dune is related to the macroturbulence of the flow, mean flow field and the instantaneous structures of the vortices generated by these forms. Details of different mechanisms and hydrodynamic process generated behind a fixed single ripple are exposed by examining a laminar flow over the dune itself. Measurements with two-component Particle Image Velocimetry, three-component Stereo-PIV and flow visualization coupled with a numerical studies are performed to acquire and to obtain a detailed knowledge of the flow over the dune concerning the three-dimensionality, the instantaneous behavior of the flow and the large dynamic of vortex in the recirculation zone along the ripple. A set experiment generating turbulent flow is conducted in a hydro-sedimentary channel to detail the quantitative measurement of bedload transport processes in order to determine the effects of the turbulent flow on dune creation. A spatio-temporal monitoring of particles transport from crest to dune slip face is conducted to point the particular role of the recirculation region. Finally, the analyze and the effect of hydraulics conditions on the critical shear stresses for incipient particle motion as well as the formation and the migration of the mobile dune are emphasized by a geomorphological st
Yuan, Chao. "Modélisation à l'échelle des pores et étude hydro-mécanique des matériaux granulaires partiellement saturés". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI033/document.
The situation of two immiscible fluids through a deformable granular material is widely encountered in nature and in many areas of engineering and science. To understand the physical evolution of the multiphase system is of great importance for the applications. It requires the knowledge of all component phases, their distribution and interactions. A pore-scale coupled hydromechanical model is presented in this thesis based on previous work, aiming at simulating the quasi-static drainage of a deformable granular materials. The model combines a pore network approach and the discrete element method (DEM) for the fluids and grains, respectively. A local criterion for determining the local movements of the fluids interfaces established to approximate the role of the local pore geometry on capillarity and namely on the forces exerted on the solid grains inside each pore. Special attentions have been paid to the entrapment events of the receding fluid and to the preferential invasion along the boundaries. The model is validated through comparisons with experimental results (water retention curves). We apply the model for examining two issues: (1) finite size effects and the concept of representative elementary volume (REV); (2) Bishop's effective stress parameter and to the relationship between macro-scale effective stress and micro-scale contact stress. Finally, an extension to the pendular regimes is proposed and first results are presented and analyzed
Rakotonirina, Andriarimina. "Fluid-solid interaction in a non-convex granular media : application to rotating drums and packed bed reactors". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN047/document.
Non convex granular media are involved in many industrial processes as, e.g., particle calcination/drying in rotating drums or solid catalyst particles in chemical reactors. In the case of optimizing the shape of catalysts, the experimental discrimination of new shapes based on packing density and pressure drop proved to be difficult due to the limited control of size distribution and loading procedure. There is therefore a strong interest in developing numerical tools to predict the dynamics of granular media made of particles of arbitrary shape and to simulate the flow of a fluid (either liquid or gas) around these particles. Non-convex particles are even more challenging than convex particles due to the potential multiplicity of contact points between two solid bodies. In this work, we implement new numerical strategies in our home made high-fidelity parallel numerical tools: Grains3D for granular dynamics of solid particles and PeliGRIFF for reactive fluid/solid flows. The first part of this work consists in extending the modelling capabilities of Grains3D from convex to non-convex particles based on the decomposition of a non-convex shape into a set of convex particles. We validate our numerical model with existing analytical solutions and experimental data on a rotating drum filled with 2D cross particle shapes. We also use Grains3D to study the loading of semi-periodic small size reactors with trilobic and quadralobic particles. The second part of this work consists in extending the modelling capabilities of PeliGRIFF to handle poly-lobed (and hence non-convex) particles. Our Particle Resolved Simulation (PRS) method is based on a Distributed Lagrange Multiplier / Fictitious Domain (DLM/FD) formulation combined with a Finite Volume / Staggered Grid (FV/SG) discretization scheme. Due to the lack of analytical solutions and experimental data, we assess the accuracy of our PRS method by examining the space convergence of the computed solution in assorted flow configurations such as the flow through a periodic array of poly-lobed particles and the flow in a small size packed bed reactor. Our simulation results are overall consistent with previous experimental work
Lefebvre, Gautier. "Incorporation de liquide dans un milieu granulaire : mécanismes du mélange". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-01061870.
Burdeau, Alexis. "Propriétés cinétiques de milieux granulaires vibrés". Paris 6, 2009. http://www.theses.fr/2009PA066249.
Obando, Vallejos Benjamin. "Mathematical models for the study of granular fluids". Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0274/document.
This Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely : • In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids : the viscous nature of the interstitial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. • In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. • In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface
Taberlet, Nicolas. "Ecoulements gravitaires de matériaux granulaires". Rennes 1, 2005. https://tel.archives-ouvertes.fr/tel-00010108.
Guillard, François. "Trainée et portance dans les milieux granulaires". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4782/document.
This thesis presents an experimental and numerical study of the forces experienced by an object moving in granular media. This problem, which is of practical importance in many applications (robots, animal locomotion), is also of fundamental interest (rheology of granular materials, granular segregation). The experiment consists in a horizontal cylinder rotating around the vertical axis in glass beads. Both drag forces and lift forces experienced by the cylinder are measured.During the first half rotation, before the cylinder crosses its own wake, we measure a strong lift force (despite the symmetry of the object), about 20 times the buoyancy of the cylinder, and independent of its depth. Molecular dynamic simulations (Discrete Element Method) shed lights on how this lift force arises from the modification of the grain flow due to the pressure gradient in the medium. After several rotations, when the cylinder goes through its own wake, the drag force drops and becomes independent of depth. The rotation of the cylinder induces a structure in the granular packing, which screens the weight of the grains above it. Finally, a numerical study of forces on a large particle flowing with the granular medium is sketched, in relation with the phenomenon of granular segregation
Bertho, Yann. "Dynamique d'écoulements gaz-particules en conduite verticale". Palaiseau, Ecole polytechnique, 2003. https://pastel.archives-ouvertes.fr/tel-00171722.
Kneib, François. "Force moyenne et fluctuations subies par un obstacle indéformable soumis à l’écoulement confiné d’un milieu granulaire". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI024/document.
The existing studies dealing with the design of civil-engineering structures against snow avalanches are generally based on force times series that are smoothed over time. However the strong heterogeneity of snow leads to systematic observations of a high level of force fluctuations. This PhD thesis aims at characterizing the force fluctuations exerted on an obstacle that is overflowed by a granular flow. Numerical simulations based on the discrete elements method are implemented to model the interaction between the snow, represented by an assembly of spherical particles, and a rigid motionless wall-like obstacle. A key feature of this work is the broad range of flow regimes investigated, from quasistatic to collisionnal. Two model systems are studied in order to focus on a zone restricted to the upstream of the obstacle, and to allow a full control of the macroscopic flow variables (shearing velocity, confinement pressure, system sizes). The first one confines the grains between four walls from which the top one imposes a constant shearing velocity while the force signals are measured on the wall facing the corresponding displacement. The second system confines the grains between a static bottom wall, a shearing top wall, and a periodic boundary condition in the shear direction, while the wall-like obstacle is fully immersed in the grains. Each system is studied through a time-averaged analysis then the fluctuations are characterized from the instantaneous force time series.The macroscopic inertial number built from the shear velocity and the confinement pressure imposed to the system turns out to be the main control variable of both the mean dynamics and the fluctuations in the systems. An empirical law has been established to predict the mean force transmission on the obstacle as a function of the macroscopic inertial number for each of the two systems, and the measurement of local strain and stress tensors revealed that the granular flow µ(I)-rheological law is respected nearly everywhere in the samples. The autocorrelations of force signals on the obstacle at the mesoscopic scale revealed the presence of a memory effect of both systems at low inertial numbers which vanishes with the transition from the quasistatic to the dense inertial flow regimes. The force distributions at three different spatial scales are also controlled by the macroscopic inertial number: for slow regimes the distributions are tightened and resemble Gaussian shapes, for fast regimes the distributions are rather exponential. Truncated log-normal probability density functions (with three parameters) have been established in order to predict empirically the force distributions on the obstacle.This work contributes to advance the knowledge on both the time-averaged and the fluctuating components of the force exerted on a wall subjected to a granular flow. The results enable to look forward with the modeling of gravity-driven systems approaching real flow conditions, thus allowing a comparison with laboratory experiments and full-scale measurements, with the aim of better designing of civil engineering structures impacted by avalanches
Fortin, Jerome. "SIMULATION NUMERIQUE DE LA DYNAMIQUE DES SYSTEMESMULTICORPS APPLIQUEE AUX MILIEUX GRANULAIRES". Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2000. http://tel.archives-ouvertes.fr/tel-00011222.
des milieux granulaires. Dans un premier temps, nous présentons
une méthode numérique par Eléments Discrets de type Dynamique des
Contacts, qui modélise en 2D le mouvement d'un ensemble de corps
rigides, entrant en collision entre eux et avec des parois, et
sujets à des forces de frottement lors de ces chocs. L'utilisation
du bipotentiel de contact conduit à un algorithme local basé sur
un schéma prédicteur-correcteur par projection sur le cône de
frottement et à un critère de convergence fondé sur un indicateur
d'erreur relative en loi de comportement. La prise en compte
exacte des conditions de Signorini et de Coulomb nous oblige à
considérer les phénomènes de chocs multiples. Dans ce cadre, nous
utilisons le formalisme de la mécanique non-régulière. Nous
aboutissons à un algorithme comportant, à chaque itération, une
phase de résolution de l'équation de la dynamique, fournissant une
nouvelle approximation de la vitesse, et une phase d'utilisation
de l'algorithme local, fournissant une nouvelle valeur de
l'impulsion. Les simulations numériques tant quasi-statiques que
dynamiques mettent en évidence la convergence et la robustesse de
l'algorithme.
Dans un second temps, pour permettre le passage de l'échelle
microscopique à l'échelle macroscopique, nous établissons une
expression du tenseur des contraintes moyen, qui prend en compte
les efforts volumiques. Nous montrons sur un exemple analytique
simple d'un grain rigide cylindrique roulant sur un plan incliné,
que les effets dynamiques sont essentiels pour symétriser le
tenseur des contraintes moyen.
Merceron, Aymeric. "Milieux granulaires réactifs : dynamique et structure autour de grains en transformation". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066473/document.
Physical and chemical transformations appearing in reactive granular media yield strong dynamical and structural reorganizations. Widely used for industrial applications, the behavior of these evolving materials needs to be understood. In this work, we experimentally study the rearrangements of a model granular packing undergoing localized transformations of one or several grains. The experimental setups allow a two-dimensional tracking of the surrounding structure while one or several grains are either reducing in size or being pulled out of the packing. The average long-term response of the material is similar to quasi-static flows commonly observed in silos. The instantaneous behavior of the packing is heterogeneous in space and time. It shows an intermittent dynamic with events decorrelated in time whose amplitudes are power-law distributed. The sizes of the evolving grains play an important role on the dynamical response of the granular packing by the appearance of arches for the smallest intruders. Moreover, the presence of a second evolving grain generates cooperative effects. A characteristic distance between the two intruders is found, it does depend on the packing properties and not on the size of the evolving grains. Finally, instantaneous evolutions of local densities show similar distributions suggesting a unique mechanism in terms of structural reorganizations
Bonnoit, Claire. "Ecoulement de suspensions granulaires modèles". Paris 6, 2009. https://pastel.archives-ouvertes.fr/tel-00463534.
Madec, Laurent. "Conception, mise en oeuvre et modélisation d'un procédé d'agglomération de particules submicroniques en vue de les rendre filtrables et redispersables". Vandoeuvre-les-Nancy, INPL, 2000. http://www.theses.fr/2000INPL064N.
Fortin, Jérôme. "Simulation numérique de la dynamique des systèmes multicorps appliquée aux milieux granulaires". Lille 1, 2000. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2000/50376-2000-41.pdf.
Bouteloup, Joris. "Simulation numérique de la dynamique d'un lit granulaire cisaillé par un fluide visqueux". Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/17966/1/Bouteloup_Joris_INPT.pdf.
Pailha, Mickaël. "Dynamique des avalanches granulaires immergées : rôle de la fraction volumique initiale". Aix-Marseille 1, 2009. https://tel.archives-ouvertes.fr/tel-00433171.
Initiation of underwater granular avalanches : inuence of the inital volume fraction. The aim of this thesis is to obtain a better understanding of geophysical ows like landslides. In those events, the coupling between the granular material and the uid play an important role during the initiation. This thesis studies physical phenomenon during the initiation of underwater granular avalanches with an experiment and a model. The ow is shown to strongly depends on the initial volume fraction, its initiation being dramtically delayed by a slight
Békri, Samir. "Dissolution et déposition dans les milieux poreux fracturés". Châtenay-Malabry, Ecole centrale de Paris, 1995. http://www.theses.fr/1995ECAP0455.
Ezaoui, Alan. "Comportement expérimental statique et dynamique des sables et modélisation "élasto-visco-plastique" anisotrope en petites et moyennes déformations". Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0036/these.pdf.
A study on sand Hostun S28 dry and saturated was conducted in small and medium deformations on a triaxial apparatus developed precisely to ENTPE. This experimental prototype can apply many types of loads on a cylindrical sample of sand, confined in a controlled air pressure. Of quasi-static loads can be applied to the sample, controlled strength and movement from the internal sensors of the cell. The extent of deformation is ensured by a system of local, arranged on the central part of the sample. Sensors without contact with high accuracy are used to study the behaviour of the material in the field of small deformations (a few 10-6 m / m) to the field of medium and large strains (some 10-2 m / m). In addition, solicitations dynamic propagation of radial and axial waves are made in the specimen from a set of piezoelectric sensors. The experimental procedure consists of tests of compression and extension triaxial in dry and saturated during which, periods of creep, relaxation periods, the rapid change in speed of solicitation, solicitation cyclical low amplitudes and dynamic wave propagation, are applied to various states of duress
Ezaoui, Alan Di Benedetto Hervé. "Comportement expérimental statique et dynamique des sables et modélisation "élasto-visco-plastique" anisotrope en petites et moyennes déformations". Villeurbanne : Doc'INSA, 2009. http://docinsa.insa-lyon.fr/these/pont.php?id=ezaoui.
Marouazi, Ghita. "Étalement de dispersions granulaires sous vibrations". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0307.
This work focuses on the spreading of granular materials under vibrations. The dynamics of granular materials is complex and diverse, sparking growing interest in research due to their frequent occurrence in nature and industry. Understanding how they are transported, stored, and mixed is essential for optimization, requiring a deep understanding of their rheological behavior. The first part of this work deals with the spreading of dry granular materials. Initially, we studied the free spreading of a fixed-mass granular pile on a rough solid surface under vibrations. We demonstrated that the shape of the pile becomes self-similar at long times, suggesting a parabolic solution. Then, we investigated the spreading of a variable-mass granular pile under vibrations. We showed that there are certain frequency ranges of vibrations that can block or slow down the avalanche of a granular pile when the excitation frequency is in resonance with system characteristics. A higher angle of repose indicates higher internal friction, making particles more resistant to slipping. The application of vibrations to a granular medium can reduce viscosity by allowing better particle spreading. This viscosity then depends on system properties and is controlled by granular pressure, particle size, gravitational force, and vibration acceleration. The second part focuses on the spreading of granular pastes under vibrations through a rheological study that involves subjecting different samples to shear within a measurement cell, similar to a Couette cell configuration. This method allowed us to explore the properties of granular paste under various conditions. This section opens up to the possibility of studying the spreading of a granular column under vibrations
Meruane, Carolina. "Equations continues pour l'étude de la dynamique des écoulements granulaires denses hétèrogènes". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00719232.
Yacoub, Boulaïd. "Étude du frottement et de la dilatance des matériaux granulaires : Expérimentation et modélisation". Artois, 2008. http://www.theses.fr/2008ARTO0210.
Duttine, Antoine. "Comportement des sables et des mélanges sable / argile sous sollicitations statiques et dynamiques avec et sans "rotations d'axes"". Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0036/these.pdf.
The behaviour of sands and mixtures of sand/clay are investigated by the means of the prototype “T4C StaDy” developped at DGCB/ENTPE, which is an innovative torsion/compression device. Independent static and dynamic loadings can be applied to a hollow cylinder specimen and the effects of induced anisotropy, sudden or continous rotation of stress principle axes, investigated under three-dimensional stress paths. Dynamic loadings are carried out thanks to piezo-electric transducers. The measurable strain range covers very small strains (several 10-6m/m) to large strains (several 10-2m/m) with an innovative local measurement system. A comprehensive series of triaxial compression tests and torsional shear tests (from an anisotropic initial stress state) were performed including creep, small cyclic and dynamics loadings. Eight terms of the compliance tensor linking strain and stress increments can be determined under small cyclic loadings. Several properties of this tensor are reported. Inverse analysis of dynamic measurements gives also several terms of the compliance tensor. Isotropic elasticity and transverse isotropic elasticity are considered. Static and dynamic measurements show a good agreement all the more since transverse isotropic elasticity is assumed in dynamic analysis. The viscous behavior of the materials can be characterized thanks to creep strains. The proposed modelling is based on a three-component model. Small strain (non viscous) behaviour and viscous behaviour are respectively simulated by the first and the third component. Experimental static, dynamic and creep results are well predicted by the model. The first component is incorporated into field wave propagation equations (cross-hole tests on a nuclear plant site) and allow to determine overall soils and soils skeletons elastic properties under isotropic and anisotropic assumptions. Results enlighten the importance of considering anisotropic soils behaviour