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Добірка наукової літератури з теми "Écoulements de Marangoni"
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Статті в журналах з теми "Écoulements de Marangoni"
Pham, Pascale, Jean-Luc Achard, Philippe Masse, and Jean Berthier. "Modélisation d'un écoulement Marangoni dans une goutte en équilibre avec sa vapeur." La Houille Blanche, no. 5 (October 2003): 58–65. http://dx.doi.org/10.1051/lhb/2003091.
Повний текст джерелаДисертації з теми "Écoulements de Marangoni"
Assemat, Pauline. "Dynamique non-linéaire des écoulements confinés : application à l'instabilité de Marangoni-Bénard et aux écoulements entre surfaces texturées." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/1225/.
Повний текст джерелаThe work focuses on two different physical situations: the convective structures resulting from the Marangoni-Bénard instability and the flow between patterned surfaces. The two systems are spatially constrained and are analysed using dynamical systems theories. Marangoni-Bénard convection has been studied in cylindrical geometries with either a circular or a weakly elliptical cross-section. The comparison of the two situations is carried out in the non-linear regime and the corresponding bifurcation diagrams are analysed using bifurcation theory with symmetries. Two-dimensional Marangoni convection in binary mixtures with Soret effect has also been studied in large periodic domains. The results show the formation of steady convective structures localized in space called convectons and the onset of stable convectons embedded in a background of small amplitude standing waves. Finally, the transport properties of flows in between patterned surfaces under weak inertia influence is studied. The flow is induced by a constant applied pressure gradient and the velocity field is calculated using an extension of the lubrication approximation taking into account the first order inertial corrections. Trajectories of tracers are obtained by integrating numerically the quasi-analytic velocity field. The transport properties are analysed by the study of Poincaré sections and their invariants
Valdez, Arnaut Héctor Gabriel. "Simulation des écoulements diphasiques en présence d'effets thermiques." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR38.
Повний текст джерелаThe development of accurate numerical approaches is required to study flows driven by surface tension gradients induced by temperature variations. Previous studies have employed various methods, including Smoothed Particle Hydrodynamics, Volume-of-fluid, levelset, and front tracking. These approaches have been demonstrated to be adopted for treating this kind of physical phenomena. The present study proposes an implementation on ARCHER, the inhouse code solver for Navier-Stokes equations, which is based on the coupled levelset and volume-of-fluid method. The impact of fluctuations in surface tension in response to temperature gradients is incorporated. Furthermore, the Boussinesq approximation is introduced to account for the buoyancy effect. Two canonical cases were subject to examination to validate this novel implementation. The first case study considers a flat interface between two fluids with a temperature gradient aligned with the interface. This results in the generation of a flow that can be analytically described for a range of scenarii, which was then reproduced through numerical simulation. The second case considers a spherical or circular bubble subjected to a temperature gradient. This results in the migration of the dispersed phase. Once more, the analytical solution is employed to validate the developed numerical approach. Finally, the impact of temperature gradients is studied by considering the Rayleigh Bénard-Marangoni instability at two limits: when driven by buoyancy and when driven by Marangoni stress. The observation of instability cells and the deformation of the interface were also noted. Finally, the final section of the manuscript addresses two-phase flow instabilities precipitated by the presence of temperature gradients. Thermoconvective instabilities induced by variations in density (buoyancy) and/or surface tension (Marangoni effect) were examined by considering boundary cases. In this study, instability cells and interface deformation were observed using the numerical approach developed
Robert, de saint vincent Matthieu. "Écoulements microfluidiques pilotés sans contact par une onde laser." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14072/document.
Повний текст джерелаThe thermocapillary (or Marangoni) effect is the mechanical result of an interfacial tension gradientinduced by a temperature gradient on a fluid interface. This effect manifests itself byinducing (i) the migration of an immersed finite-size object (droplet, bubble), and (ii) a deflexionof the interface. Due to its interfacial nature, the Marangoni effect is particularly relevantat small length scales, especially in the context of two-phase microfluidics. This thesis aims atapplying the thermocapillary effect locally induced by laser heating, in order to create some basicoptofluidic actuators (valve, switch, sampler). A quantitative study of these actuators is presented.The laser-forced destabilization of a co-flowing microfluidic jet, leading to its breakup,is also investigated. This “optical toolbox” represents a non-contacting, and microfabricationfreeapproach for the production and handling of droplets in digital microfluidics. Moreover, tocharacterize these droplet over long times, thus considering statistically significant populations,a simple optoelectronic device has been developed for measuring the size and velocity of thedroplets in real time
Kervil, Ronan. "Matière active et écoulements : jets de bactéries et nageurs interfaciaux." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1039/document.
Повний текст джерелаThis work address different situations where active matter, made out of self-propelled particles, is submitted to external constraints.In a first part, we consider the response of magnetotactic bacteria –capable of swim alignment along magnetic field lines- directed through an hourglass shape geometry. We characterize the dynamic properties of the system, both at the individual bacteria scale and at the scale of the jammed region or of the induced outgoing jet. We show that in high density regions, couplings between the bacteria interactions, swim velocity and magnetic forcing take a much more complex form than had been considered so far in theoretical models.In a second chapter, we are addressing a new active system made out of camphor disks lying at the air-water interface. First of all, we study in details the individual swim properties of such particles, which spontaneously break the system symmetry to start moving. In particular, we show that all experimental data can be rationalized within the framework of a very simple model of this complex problem where hydrodynamic flows and surfactant transports are coupled through Marangoni stress.In a last chapter, we addressed the collective dynamics of an assembly of such interfacial swimmers that interact through the flow and chemical fields they generate. At intermediate swimmers concentrations, an intermittent swim regime appears characterized by pseudo-periodic activity bursts. Using tools and concepts from the turbulence domain, we show that, remarkably, this simple system exhibits dynamical properties matching the ones of canonical turbulence as predicted by Kolmogorov in the 40s. This demonstration opens up rich perspectives in the historical domain of turbulence together with in the emerging one of active matter
Robert, De Saint Vincent Matthieu. "Écoulements microfluidiques pilotés sans contact par une onde laser." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-00532632.
Повний текст джерелаSaadlaoui, Yassine. "Simulation numérique des procédés thermomécaniques dans une approche couplant les écoulements du fluide avec les déformations du solide : application au soudage laser et à la fusion d'un lit de poudre." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSES005.
Повний текст джерелаIn the current study, numerical methods are developed to simulate the laser welding and the melting of a powder bed while taking into account their complexity. These methods are based on a new strategy of fluid/solid coupling. They allow to simulate the formation of the melted zone by taking into account the fluid flows through the two effects of the surface tension ("curvature effect" and "Marangoni effect") and the buoyancy. An ALE approach is used to follow the evolution of the free surface. The interaction between the fluid flows in the molten pool and the deformations in the solid part is ensured by imposing the velocities of the solid nodes during the fluid computation. Several analytical and numerical tests are used to validate the formulation of the fluid problem and the new strategy of fluid/solid coupling. The results confirm the efficiency and the robustness of the numerical methods developed.As first application, a thermal-fluid-mechanical simulation of laser welding is carried out. The results obtained show a good correlation with the literature results. The second application consists of simulating the melting of a powder bed. It allows to take into account the shrinkage of the powder layer after melting, and the change of the thermalphysical properties depending on the material state (powder or compact).Although the study consisted mainly in developing numerical methods, it also includes an experimental part. Specific set-up has been done using different instrumentation tools. These tools allow to better understand the physical phenomena involved during the two processes. In a second step, a database (morphology of molten pool, temperature and residual stresses) on welded parts is constituted. This database will allow in a subsequent work to carry out a global validation process of the proposed numerical methods
Bammou, Lahcen. "Instabilité thermoconvective d'un écoulement Poiseuille-Rayleigh-Bénard-Marangoni en canal ouvert à surface libre." Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3030/document.
Повний текст джерелаSeveral studies both numerical and experimental have reported the presence of thermal instabilities in liquid films uniformly heated from below for specific boundary conditions and flows. The presence of these instabilities modifies the associated heat transfer. The subject of this PhD thesis is to study numerically the instability of three-dimensional laminar mixed convection within a liquid flowing on a horizontal channel heated uniformly from below. The upper surface is free and assumed to be flat. The variations of the surface tension with the temperature (Marangoni effect or thermocapillary effect) are taken into account. Although of great interest for many industrial applications, this problem has received little attention from an academic point of view. In this configuration, several types of thermoconvective structures may appear. When the strength of the buoyancy, thermocapillary effects and forced convective currents are comparable, the results show the development of instabilities in the form of steady longitudinal convective rolls similar to those encountered in the Poiseuille-Rayleigh-Bénard flow. To our knowledge, this is the first time that the Poiseuille-Rayleigh-Bénard flow associated to the Marangoni effects has been investigated. The number and spatial distribution of the convective rolls along the channel depend on the flow conditions. We propose a numerical study on the flow conditions that could lead to thermal instabilities with an evaluation of their effect on the heat transfer. The coupled Navier-Stokes and energy equations are solved numerically by the finite volume method taking into account the thermocapillary effects. The results presented concern the influence of several control parameters (the Reynolds, Rayleigh, Biot and Marangoni numbers and the aspect ratio of the channel) on the flow patterns and heat transfer characteristics. In the second part of this work, complimentary to the first, a linear stability analysis of a horizontal liquid film flowing in an open channel, with infinite lateral extension and uniform heating from below, is carried out. An eigenvalue problem is obtained in the course of this analysis which is solved numerically using the Chebyshev collocation spectral method. The stability diagrams determining the threshold parameters leading to thermoconvective instabilities were obtained and analyzed as well as the associated spatial patterns
Carvalho, Victor. "Mise en oeuvre de méthodes optiques de vélocimétries 2D et 3D appliquées à l’étude de l’effet Marangoni autour d’une bulle unique." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2073/document.
Повний текст джерелаThe Marangoni convection is a phenomenon that appears in the presence of a tension surface gradient along an interface between two immiscible fluids. It is possible to observe that appear convection around vapor bubbles in the heat exchangers with the phase change. However, the Marangoni convection has been neglected to other phenomena involved in the heat transfer. In the age of miniaturization, it becomes impossible to overlook this micro convection. The aim of this thesis si to characterize the dynamics of Marangoni convection around a bubble. The first part deals with the 2D results around an air bubble in the presence of a temperature gradient. This case is easier to implement and allows having a better knowledge with the Marangoni convection. The second part focuses on the two-dimensional study of the convection around a vapor bubble The results showed that the phenomenon quickly became three-dimensional. The last section therefore presents a method for measuring optical innovative 3D3C
Koleski, Goce. "Flower-like azimuthal instability of a divergent flow at the water/air interface." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0244.
Повний текст джерелаAxisymmetric flows on a water-air interface prove to be azimuthally unstable. In this thesis work, we design two setups to explore this fact : (1) a small subaquatic fountain propelling a jet against the water-air interface where it creates a centrifugal radial flow, (2) a laser – heated microbead in partial wetting at the surface of water that induces a divergent thermocapillary flow. At sufficiently high jet speeds or laser powers appears a symmetry – breaking of the toroidal base flow in the form of counter – rotating vortex pairs surrounding the source. Morphological traits of the torus and the dipole are uncovered through a wealth of laser tomography and dye injection experiments. In the water jet experiment, we show that the torus size is primarily fixed by the distance between the injector and the surface. In both experiments,the tracking of tracer particles evidences a ‘locked’ interface in the toroidal regime, whereas it ‘unlocks’ when a dipole sets in. Such a phenomenon is conditioned by surface elasticity. Cogent evidence is brought by the elastic response to laser shutdown of a surfactant layer adsorbed at the water surface. Unveiling the key role of surface elasticity in the scenario of the instability is the main achievement of this work.On a theoretical level, we focus on thermocapillary convection induced by a fixed point source of heat sitting across the water-air interface. We solve the incompressible Stokes equation within the water – filled half – space and derive an exact solution to the advective nonlinear regime in the far – field axisymmetric limit. We then lay the groundwork on which to build a model of the instability. This thesis work paves the way for understanding how a hot microsphere found on the water surface triggers such an instability, thereby becoming an ‘active particle’ able to achieve self – propulsion at large speeds
Clerget, Mattéo. "Formation et destruction de mousse en écoulement dans un milieu confiné." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS493.
Повний текст джерелаFoam injection into porous media is a highly promising technique for a wide range of applications, including carbon dioxide storage, soil remediation, and enhanced oil recovery. The flow of this foam in a confined environment brings into play different processes of formation or destruction of the bubbles of which it is composed. Understanding the physical mechanisms of these processes is essential to improve this technique, in particular by optimizing the formulation of the liquid phase.Our approach is to decouple these different phenomena, using two-dimensional flow model devices, at the micro- or milli-fluidic scale. Their transparency allows us to visualize the structure of the flowing foam and to relate it to its macroscopic properties. Various surfactants and additives are systematically tested to investigate the ability of our devices to screen them, and the results obtained are systematically compared with those obtained in porous media.Our first experiment, which studies the formation of bubbles during the passage of a gas/liquid co-flow in a microfluidic pore, highlights a formation hysteresis phenomenon explained by a hydrodynamic feedback process initiated by the downstream flow. Using numerical simulations, we also demonstrate the existence of a limit to the quality of foam that can be formed, linked solely to the pore geometry. Different surfactants are investigated, and these results are compared with measurements both in volume and in three-dimensional porous media.Our second experiment studies the influence of an additive on this formation, in particular through the Marangoni effects it generates. A simple theoretical model is developed to account for these effects.Finally, we describe a millifluidic setup for observing and studying foam destruction by bubble coalescence. We show that the results vary drastically depending on the surfactants and additives used