Tesis sobre el tema "Dynamique des fluides – Simulation, Méthodes de"
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Gevrin, Frédéric. "Modélisation dynamique de la fluidisation solide-liquide". Toulouse, INPT, 2002. http://www.theses.fr/2002INPT002G.
Texto completoEttaouil, Abdeslem. "Etude numérique du champ aérodynamique d'une hélice aérienne isolée ou en interaction avec une voilure : validation par comparaison de l'expérience". Aix-Marseille 2, 1987. http://www.theses.fr/1987AIX22093.
Texto completoMate, Annie. "Intéractions goutte-paroi dans un contacteur liquide-liquide". Toulouse, INPT, 1998. http://www.theses.fr/1998INPT008G.
Texto completoSicot, Frédéric. "Simulation efficace des écoulements instationaires périodiques en turbomachines". Ecully, Ecole centrale de Lyon, 2009. http://www.theses.fr/2009ECDL0019.
Texto completoMany industrial applications involve flows periodic in time. Flutter prediction or turbomachinery flows are some examples. Such flows are not simulated with enough efficiency when using classical unsteady techniques as a transient regime must be by-passed. New techniques, dedicated to time-periodic flows and based on Fourier analysis, have been developed recently. These methods, called harmonic balance, cast a time-periodic flow computation in several coupled steady computations, corresponding to a uniform sampling of the period. Their efficiency allow to get a precision good enough for engineering but much faster than classical nonlinear timemarching algorithms. The present study aims at imlementing one of these, the Time Spectral Method, in the ONERA solveur elsA. It is extended to an arbitrary lagrangian/eulerian formulation to take into mesh deformation for aeroelasticity applications. New implicit algorithms are developped to improve robustness. The TSM is successfully validated on external aerodynamic applications. Turbomachinery flows necessitate complex space and time interpolations ro reduce the computational domain to a single blade passage per row regardless of its geometry. Some applications in rotor/stator interactions and aeroelasticity are presented
Louste, Christophe. "Conception d'une méthode de planification de déplacement pour robot mobile selon la méthode des milieux continus appliquée aux fluides visqueux incompressibles". Montpellier 2, 1999. http://www.theses.fr/1999MON20196.
Texto completoDuguet, Yohann. "Simulation numérique de l'instabilité dans un cylindre de gaz tournant soumis à une compression périodique". Ecully, Ecole centrale de Lyon, 2004. http://www.theses.fr/2004ECDL0021.
Texto completoThis work concerns the direct numerical simulation of a new instability phenomenon occuring in confined rotating gas flows. It confirms the analytical results of J. F. Scott and J. P. Racz (2001) and the experimental work of L. Graftieaux (2003). A parametric resonance mechanism leads to conditional growth of inertial mode pair coupled by harmonic oscillations of a piston. A numerical code was developed under the assumption of axisymmetry of the flow, based on a galerkin-type spectral method. Special treatment of the velocity singularities in the cylinder corners is based on the substraction of an analytical lly specified flow the mimics the corner singularities. The results allow complete characterization of inertial mode pairs coupled by resonance, with particular attention focused on the primary axisymmetric mode studied experimentally. A marginal stability diagram and an exploration of the nonlinear regime were performed
Wernert, Philippe. "Méthodes de visualisation et de PIV appliquées à l'étude du décrochage dynamique profond et comparaison avec des résultats de simulation numérique". Aix-Marseille 2, 1997. http://www.theses.fr/1997AIX22110.
Texto completoLaucoin, Eli. "Développement du parallélisme des méthodes numériques adaptatives pour un code industriel de simulation en mécanique des fluides". Phd thesis, Grenoble 1, 2008. http://www.theses.fr/2008GRE10174.
Texto completoNumerical resolution of partial differential equations can be made reliable and efficient through the use of adaptive numerical methods. We present here the work we have done for the design, the implementation and the validation of such a method within an industrial software platform with applications in thermal-hydraulics. From the geometric point of view, this method can deal both with mesh refinement and mesh coarsening, while ensuring the quality of the mesh cells. Numerically, we use the mortar elements formalism in order to extend the Finite Volumes-Elements method implemented in the Trio-U platform and to deal with the non-conforming meshes arising from the adaptation procedure. Finally, we present an implementation of this method using concepts from domain decomposition methods for ensuring its efficiency while running in a parallel execution context
Laucoin, Eli. "Développement du parallélisme des méthodes numériques adaptatives pour un code industriel de simulation en mécanique des fluides". Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00385418.
Texto completoPaliard, Chloé. "Dimension reduction for fluid simulation and animation". Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAT023.
Texto completoDespite tremendous improvements in graphics hardware performance aswell as key algorithmic advancements since the beginning of the years 2000, some natural phenomena remain extremely costly to simulate. For instance, several tracks have been proposed to improve the performance of fluid simulations, that are animated by solving partial differential equations (PDE), more specifically the highlynon-linear Navier-Stokes equations. In this thesis, we first explore the use of deep learning to create a reduced space in which a solver can operate with lower costs, while still out putting high-quality solutions. We propose a model that enables the simulation of turbulent flows at a resolution four times higher than that of the given input in each dimension, with improved runtime performance compared to a high-resolution solver. Secondly, we use the contributions on intrinsic operators for simulating fluids on 3D surfaces with reduced costs. We focus on the smoothed-particle hydrodynamics (SPH) model that we adapt to 3D surfaces, by gathering the particles' neighborhoods thanks to shortest-path geodesics, and by displacing such particles in an intrinsic manner on the surface. All of this is straightforward to implement on the GPU, enablingthe simulation of tens of thousands of particles on various triangle meshes at interactive speed
El, Soueidy Charbel-Pierre. "Éléments finis discontinus multi-domaines en temps pour la modélisation du transport en milieu poreux saturé". Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/public/theses_doctorat/2008/EL_SOUEIDY_Charbel-Pierre_2008.pdf.
Texto completoThis work treats the modeling of mass transport in porous media. The advective part of the transport equation is solved using the discontinuous Galerkin (DG) finite element method. In the first part, the discretization of the spatial operator is considered and two approximation spaces are studied and compared for unstructured meshes in 2-D. The temporal discretization is tackled in the second part of this study. Two alternatives to the traditional explicit scheme are presented : a class of semi-implicit schemes and an explicit local time-stepping procedure which allows spatially varying time steps. Finally, the last part of this work consists of using the developed numerical tools to simulate density coupled flow and transport in porous media. The local time procedure is implemented in a 3-D numerical code and numerical experiments show that the model gives accurate results being highly efficient for this kind of problems
Guilcher, Pierre-Michel. "Contribution au développement d'une méthode SPH pour la simulation numérique des interactions houle-structure". Nantes, 2008. http://www.theses.fr/2008NANT2065.
Texto completoVial, Christophe. "Apport des méthodes de la mécanique des fluides à l'étude des contacteurs gaz/liquide : expérience et simulation numérique". Vandoeuvre-les-Nancy, INPL, 2000. http://docnum.univ-lorraine.fr/public/INPL_T_2000_VIAL_C.pdf.
Texto completoThis work is devoted to the experimental study, the modelling and the numerical simulation of the hydrodynamics of a bubble column and an external loop airlift reactor. It includes three parts. First, measuring techniques have been developed to study the local and global hydrodynamic parameters of the bubbly flow. In this section, several treatments of the fluctuating wall pressure signal have been developed to identify the prevailing flow regime; three measuring techniques have been adapted to bubbly flows in order to measure the local velocity of the continuous phase: the "Pavlov" tube, an electrochemical method and Laser Doppler Velocimetry. These techniques have completed the methods already available to study the dynamics of the gas phase: local optical probes and an ultrasound Doppler technique. Then, this set of measuring techniques has been used to characterise the hydrodynamics in both reactors. Regime transitions have been deterrnined. The local and global parameters which have been measured are: the gas hold-up; the velocity, the size and the morphology of the bubbles; the liquid velocity and its local fluctuations. The Reynolds shear stress, which could not be measured, has been estimated using a simple model. The evolution of these parameters has been related to the gas flow rate, the gas distribution and the hydrodynamic regime. The whole experimental data are finally compared to the predicted values obtained using a commercial CFD code. Several models of drag, additional forces and turbulence have been used to obtain the best agreement between calculations and experiments. The ability of this commercial code to predict correctly the flow and its current limits have been highlighted
Roux, Yann. "Étude de l'amortissement visqueux dans les problèmes de tenue à la mer d'un flotteur immergé". Le Havre, 1999. http://www.theses.fr/2002LEHA0005.
Texto completoDenel, Bertrand. "Simulation numérique et couplage de modèles thermomécaniques puits-milieux poreux". Pau, 2004. http://www.theses.fr/2004PAUU3021.
Texto completoIn order to interpret recorded temperatures in petroleum wellbores, and thus to better characterize reservoirs, we develop a direct model, coupling the wellbore and the reservoir at both dynamic and thermal levels. To reach this goal, we couple a reservoir model, notably including viscous dissipation and compressibility effect, with a new pseudo 1D model. The original aspect of the latter model is to derive a conform approximation from a 2D model and by this way, to take into account the privileged direction of the flow, as well as the particular geometry of the wellbore, by explicitly writing the dependency of the unknowns in the radial direction. For each model, the fluxes are approximated by conservative Raviart-Thomas elements, ensuring natural transmission conditions at the interface. An analysis of the resulting mixed formulations is carried out and the well-posedness of the semi-discretized problems is established. Then, numerical results including real study cases are presented. Finally, a global coupling approach of the two models is exposed
Bousquet, Nathalie. "Prise en compte de l'intermittence de frontière dans la modélisation des écoulements cisaillés turbulents". Toulouse, INPT, 1999. http://www.theses.fr/1999INPT040H.
Texto completoCallot, Stanislas. "Analyse des mécanismes macroscopiques produits par les interactions rotor/stator dans les turbomachines". Ecully, Ecole centrale de Lyon, 2002. http://bibli.ec-lyon.fr/exl-doc/scallot.pdf.
Texto completoUnsteady phenomena produced by the relative motion between fixed and moving rows in turbomachinery is caracterized by different scales in space and time. From the numerical point of view, taking into account those effets requires new models. The purpose of this work is a better understanding of the unstaeday mechanisms in a multistage turbomachinery. In ordre to cast of any restricting hypothesis over the spatial periodicities, numerical simulations are operated over the whole circumference of each row. In the single stage case, it is shown that the unsteady flow presents a phase-lagged periodic condition which may be described by the double Fourier decomposition proposed by Tyler & Sofrin. The spatial modes precise the interaction between rows and a comparison is made with the Adamczyk's decomposition. The numerical simulation of a one and a half stage brings an extension of the analysis of the interactions in a multistage machine
Abide, Stéphane. "Une méthode de décomposition de domaine pour la simulation numérique directe : contribution à l'étude de jets plans en impact". Nantes, 2005. http://www.theses.fr/2005NANT2081.
Texto completoDirect Numerical Simulation is a powerful tool in Fluid Mechanics since it allows to describe accurately both in space and time the kinematic and dynamic features of a flow. However, due to the desirable high order discretization, this approach is often restricted to simple geometries. This work proposes a domain decomposition method dedicated to the numerical simulations of turbulent flows which is based on a direct multi-domain solution of the Navier-Stokes equations formulated in primitive variables. The method solves efficiently (parallelization) the incompressible Navier-Stokes equations on " complex " geometries, like inter-connected quadrilaterals, while preserving high order accuracy. Numerous validation test cases are proposed including space/time accuracy, the lid driven cavity, the backward facing step and the flow around a square cylinder. A Direct Numerical Simulation of a square pipe flow is also performed. For fast cooling applications, a preliminary study of the propagation front of the temperature within a thin plate by using plane laminary impinging jet is presented. Finally, an important part of this work is devoted to the study of plane jet impinging on a plane surface and a cubical obstacle for a Reynolds number equal to 3000. A detailed analysis of the statistical, spectral and structural properties of the flow is achieved to obtain a better understanding of the complex phenomena occuring in such a configuration
Strozzi, Camille. "Etude expérimentale de l'auto-inflammation de mélanges gazeux en milieux confinés et sa modélisation avec une description cinétique chimique détaillée". Poitiers, 2008. http://www.theses.fr/2008POIT2275.
Texto completoSelfignition of homogeneous CH4/air and n-C4H10/air mixtures is studied within a Rapid Compression Machine. In a first step of the analysis, the combustion process is studied by using pressure measurements (ignition delays and global heat release rates). Then, temperature heterogeneities are evidenced thanks to Schlieren imaging. Their influence on the ignition process is confirmed by using direct light visualizations. The flow field and temperature distribution are then characterized in non-reactive conditions using velocimetry (fast PIV) and fluorescence (PLIF toluene) methods. Gathered information provides a better understanding of the ignition phenomena, where propagation of intense reaction zones results from autoignition fronts or processes similar to deflagrations. In parallel, a PDF method is retained for the modelling of autoignition in these conditions. The proposed strategy accounts for (i) detailed chemical kinetics, and (ii) mixing and heat transfer phenomena that play a crucial role in the evolution of temperature distribution. The comparison of the results to experimental data suggests that the proposed approach is a well suited framework for the study of this combustion mode
Kostenko, Romaric. "Simulation d'écoulements non-newtoniens en milieu poreux macroscopique par la méthode de lattice-Boltzmann". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS561.
Texto completoA non-newtonian fluid is a fluid which relation between it's shear rate and the stress under which it is put, is not linear. In a porous medium, the stress imposed to the fluid depends on the imposed pressure, but also on the pores size, and therefore on the macroscopic scale permeability. Some fluids have a rheology such that the fluid show a change of behaviour reaching a yield stress. If the pore size is random, then the fluid will present heterogeneous regime changes in the medium. The flow will then show a first regime where the whole fluid will be under the threshold, a regime where the whole fluid will be far above the threshold, and an intermediate regime for which both rheologies coexists. We are interested in intermediate regime for the flow of non-newtonian fluids in macroscopic porous media, and study it with numerical simulations. More particularly, we look at the flow of a Bingham fluid and that of a Carreau fluid. The Bingham fluid doesn't flow under a yield stress. Under the threshold, it behaves as a solid. Beyond, it's shear-rate/stress relation is an affine law. Carreau fluids have a shear-rate/stress relation that change regime between that of a newtonian fluid, and a power law. The macroscopic scale study is done simulating a Darcy-Brinkman law in a heterogeneous permeability field. We use for our simulations the lattice-Boltzmann method, on a regular node grid, and more specifically Irina Ginzburg two relaxation-time scheme. For each fluid, we study the flow-pressure relationship, as well as the geometric properties and the multi-scale properties in the fluid regions in the same flow regime (clusters), properties such as their size and shape. We also link these geometrical properties to the percolation theory, which studies the behaviour of randomly opening node maps and predicts fractal properties
Blanco, Alvarez Armando. "Quelques aspects de l'écoulement d'un fluide visqueux autour d'une bulle déformable : une analyse par simulation directe". Toulouse, INPT, 1995. http://www.theses.fr/1995INPT103H.
Texto completoMekhlouf, Réda. "Modélisation XFEM, Nitsche, Level-set et simulation sous FEniCS de la dynamique de deux fluides non miscibles". Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/30205.
Texto completoThe two-phase flow problems have an important role in the multitude of domains in science and engineering. Their complexity is so high that the actual models can solve only particular or simplified cases with a certain degree of precision. A new approach is a necessity to understand the evolution of new ideas and the physical complexity in this kind of flow, to contribute to the study of this field. A good study requires solid and robust tools to have performing results and a maximum of efficacy. At the interface of separation between the two immiscible fluids, the physical parameters are discontinuous, which gives us difficulties for the description of the physical variables at the interface and boundary conditions. The fact that the density and the viscosity are discontinuous at the interface creates kinks in the velocity, which represent a weak discontinuity. The existence of the surface tension at the interface create a discontinuity for the pressure field, it represents a strong discontinuity. The main objective of this work is to make a complete study based on strong and robust physical, mathematical and numerical tools. A strong combination, capable of capturing the physical aspect of the interface between the two fluids with a very good precision. Building such a robust, cost effective and accurate numerical model is challenging and requires lots of efforts and a multidisciplinary knowledge in mathematics, physics and computer science. First, an analytical study was made where the one fluid model of the Navier-Stokes equation was proved from Newton’s laws and jump conditions at the interface was proved and detailed analytically. To treat the problem of discontinuity, we used the XFEM method to discretize our discontinuous variables. Due to the large distortion encountered in this kind of fluid mechanic problems, we are going to use the Eulerian approach, and to correct the oscillation of solutions we will use the SUPG/PSPG stabilization technic. The treatment of the interface curvature k was done with the Laplace Beltrami operator and the interface tracking with the Level-set method. To treat the jump conditions with a very sharp precision we used the Nitsche’s method, developed in different cases. After building a strong mathematical and physical model in the first parts of our work, we did a numerical study using the FEniCS computational platform, which is a platform of computational development based on C++ with a Python interface. A numerical code was developed in this study, in the case of two-phase flow problem, based on the previous mathematical and physical models detailed in previous sections.
Rivero, Mayela. "Étude par simulation numérique des forces exercées sur une inclusion sphérique par un écoulement accéléré". Toulouse, INPT, 1991. http://www.theses.fr/1991INPT080H.
Texto completoDenis, Roland. "Modélisation et simulation de l'effet Leidenfrost". Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENM111/document.
Texto completoThe Leidenfrost effect is a special case of calefaction: when a liquid is dropped on a surface which temperature is far hotter than the liquid's boiling point, he evaporates before touching the hot plate and the produced gas forms a thin layer, under the liquid droplet, that makes it hovering and isolates it from the heat source.This thesis deals with the modeling and the numerical simulation of this complex phenomenon. In the first part, we study a sharp interface model that supplement the Navier-Stokes equations with interfacial conditions taking into account the phase change and the surface tension. Simulating an uniform liquid layer over a vaporous film reduces the problem to one dimension. The ALE method (Arbitrary Lagrangian Eulerian) is then used to deal with the variable height of each phase. The numerical code is finally validated on a test case.In the second part, the gas/liquid interface is captured by a Level-Set method. The interface is artificially thickened and inner regularization is applied to the thermodynamic quantities. Therefore, surface tension and phase change are approximated by volume terms. Each pure phase is supposed to be incompressible but, due to the phase change, the velocity field is not divergence-free in the interfacial zone.The third part focusses on the discretization of this three-dimensional model, for the simulation of a motionless and rotational symmetric droplet. The problem reduces to an axisymmetric two-dimensional setting. The use of the Level-Set method requires devoted numerical algorithms which are developed: non-diffusive efficient advection scheme, reinitialization by Hamilton-Jacobi equation with global volume correction taking into account the phase change. An adapted Chorin projection algorithm is used to ensure the prescribed compressibility constraint that holds on the interfacial fluid. In addition, we introduce a new finite difference scheme for the gradient approximation that uses a compact stencil.The last part describes and compares our simulation results with several theoretical curves based on different droplet shape simplifications, plotting the evolution of indicators like the volume and radius of the droplet, or the height of the vapor layer
Chatellier, Patrice. "Simulation de l'hydrodynamique des chenaux d'oxydation par l'utilisation des équations de Navier-Stokes associées au modèle k-epsilon : évaluation de la vitesse de circulation". Toulouse, INSA, 1991. http://www.theses.fr/1991ISAT0027.
Texto completoLouedin, Olivier. "Simulation numérique des processus de mélange 3D dans la zone naissante des jets supersoniques". Rouen, 1999. http://www.theses.fr/1999ROUES086.
Texto completoHauville, Frédéric. "Optimisation des méthodes de calculs d'écoulements tourbillonnaires instationnaires". Phd thesis, Université du Havre, 1996. http://tel.archives-ouvertes.fr/tel-00125000.
Texto completoLe cadre général de cette thèse est l'amélioration de l'efficacité de ces méthodes sous trois aspects :
- décomposition linéaire / non linéaire
- approximation par domaine
- la programmation parallèle (PVM).
Des applications concernant des problèmes d'énergie éoliens, soit sur des générateurs à hélice (éolienne), soit sur les voiles de bateau pour l'interaction fluide/structure sont développés.
Cousin, Laurent. "Simulation de sillages par méthode de projection spectrale multidomaine et technique de pénalisation : application au sillage d'une sphère en fluide stratifié thermiquement". Nice, 2004. http://www.theses.fr/2004NICE4086.
Texto completoBenjelloun, Saad. "Quelques problèmes d’écoulements multi-fluide : analyse mathématique, modélisation numérique et simulation". Thesis, Cachan, Ecole normale supérieure, 2012. http://www.theses.fr/2012DENS0074/document.
Texto completoThis thesis contains three independent parts.The first part presents a proof of existence of weak global solutions to a Vlasov-incompressible-Navier-Stokes system with variable density. This system is obtained formally from a classical Vlasov-incompressible-Navier-Stokes model with fragmentation for which only two values for the particules radii are considered: a radius r1 for non fragmented particules and a radius r2<
Gueye, Abdoulaye. "Modélisation et simulations numériques des écoulements et instabilités thermiques de fluides non-Newtonien en milieu poreux". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10154/document.
Texto completoThe present thesis on porous media concentrates in two parts. The first concerns the numerical study of the flow of a Newtonian or a non-Newtonian fluid within a fluid/porous system. The approach of a single domain, which consists of/in writing the Navier-Stokes equation including the Darcy-Brinkham-Forchheimer term, is chosen in this study. The linear relation between the pressure gradient and the bulk velocity in the Darcy case, for which the fluid is Newtonian, is obtained. This relation is extended to the non-Darcy case, for which the fluid is non-Newtonian. The influence of Darcy and Forchheimer numbers on the structure of the flow is presented. In the second part, linear stability and numerical analysis of the natural convection of viscoelastic fluids saturating a horizontal porous layer heated by a constant flux is performed. A primary and secondary instability study allowed to show that, for a Newtonian fluid, the unicellular convection loses its stability to the benefit of longitudinal rolls. In the case of viscoelastic fluids, the elasticity of the fluid leads to the selection of propagation transverse rolls. A numerical solution based on a finite difference scheme has reinforced these analytical results
Fan, Yilin. "Distribution des fluides et intensification des transferts thermiques dans un échangeur thermique par l'intégration des distributeurs constructals". Chambéry, 2008. http://www.theses.fr/2008CHAMS040.
Texto completoThis thesis contributes to the advances in the conception, fabrication, modeling, experiment, and optimization of multi-scale fluid distributors. The function of such fluid distributors is to deliver a controlled amount or rate of fluid to an array of distributing ports, in order for example to feed uniformly the channels of a multi-channel heat exchanger and consequently intensify the heat transfer with the least increase of pressure drop. Their multi-scale internal channel structures are optimized by minimizing the viscous dissipation and the residence time simultaneously according to the "constructal theory". Polymer and metallic prototypes of the constructal components were fabricated using Stereolithography. Constructal distributor prototypes were assembled with a mini crossflow heat- exchanger to evaluate the effects of flow distribution on its thermal and hydraulic performances by experiments and by Computational Fluid Dynamics (CFD) simulations. The enhancement of heat transfer realized by flow uniform distribution and the thermal- hydraulic balance are discussed. The results indicate that the integration of one constructal collector at the outlet of the heat exchanger can approach the uniform flow distribution and consequently better intensify the heat transfer. It is also the most advantageous configuration based on a balanced consideration of heat transfer intensification and pump power consumption under the investigation conditions. The results may provide some original information and thoughts to the design and optimization of heat exchangers and flow distribution/collection systems
Bonometti, Thomas. "Développement d'une méthode de simulation d'écoulements à bulles et à gouttes". Toulouse, INPT, 2005. https://hal.science/tel-04582704.
Texto completoThis work deals with the development of an interface-capturing method aimed at computing three-dimensional incompressible two-phase flows that may involve high density and viscosity ratios and capillary effects. The applications we have in mind concerns chemical engineering as well as environmental problems. We use a front-capturing method to advance the interface but do not perform any explicit reconstruction. We show that the base version of this method results in a smearing of the fronts in regions where the flow undergoes a stray stretching. We propose an improved technique in which the local velocity field within the fronts is modified and the above problem is fixed. This algorithm allows the interfaces to deform properly while maintaining the numerical thickness of the transition region within three computational cells. A detailed study of several aspects of the dynamics of two- and three-phase flows, such as drops in microchannels or hydrodynamic interactions in a bubble swarm, is then performed in both axisymmetric and three-dimensional configurations. The results concerning microfluidics are compared with very recent experiments. Finally, a study of the dynamics of a bubbly suspension involving up to 27 bubbles allow us among other things to enlighten the influence of the bubbles Reynolds number on the velocity fluctuations induced in the liquid
Galmiche, Martin. "Interaction turbulence-champs moyens et ondes de gravités internes dans un fluide stratifié". Toulouse, INPT, 1999. http://www.theses.fr/1999INPT017H.
Texto completoCouto-Barba, Laurent. "Contribution à la simulation du mélange turbulent par la schématisation de fonctions densité de probabilité". Pau, 2005. http://www.theses.fr/2005PAUU3014.
Texto completoThis thesis considers a method which simplifies the mixing at different levels, depending on turbulence length and time scales. The analysis is here restricted to the case of homogeneous and isotropic turbulent flows. The model is based on elementary fluid particles considered in their different levels of neighborhoods. For each vicinity level, a specific mixing model is applied. The approach takes into account - from small to high length scales - laminar diffusion (Fick diffusion process), internal mixing into fluid particle (Kerstein model, 1988), external mixing between fluid particles contained into a same eulerian volume (inspired from the LMSE model developpef by Dopazo, 1974, or from the Curl model,1963) and turbulent dispersion (where lagrangian moves are computed). An internal clock organizes the sequence of applications of the different models. Each one is applied instantaneously at different periodic times. Two different cases have been studied. The first case is the time evolution of mixing between two components initially introduced in two different areas. The numerical results have been compared to those of Direct Numerical Simulations by Eswaran & Pope (1988). The time evolution of Probability Density Functions, and the evolutions of variance, symetry coefficient and flatness coefficient have been compared. A parametrical study of the parameter governing the sequence of application of the different models has been performed. The second case considers thermal mixing layers emitted from one or two hot films placed inside a grid turbulence with uniform mean flow. Numerical results are in qualitative agreement with the experimental results by Warhaft (1984)
Garrelie, Florence. "Simulation Monte Carlo de l'expansion d'un panache plasma créé par ablation laser - Comparaison avec l'expérience". Limoges, 1998. http://www.theses.fr/1998LIMO0030.
Texto completoImbs, Julien. "Modélisation numérique de débitmètre électromagnétique". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE047.
Texto completoThis work concerns numerical modelling and study of electromagnetics flowmeters developed by Siemens. These devices are able to measure the flowrate of a conductive fluid in motion subject to a magnetic field. An induced potential is created and measured by two electrodes. The main purpose of this thesis is to modelize an electromagnetic flowmeter in order to get a realistic and reliable model to optimize the sensor in the futur. The first part of the work is to introduce the development theory of elec-tromagnetic flowmeter since the discovery of the induction law of Farady until today. The chapter II describes the industrial electromagnetics flowmeters manufactured by Siemens and provides the necessary knowledges for a better understanding of this work. In the chapter III, the electromagnetic flowmeter equation is derived and solved for the case of a homogenous magnetic field and point electrodes. This equation allows to get a relation between the induced potential, the velocity of the fluid and the magnetic field. We will discuss about the assumptions choose for this theory and used for the numerical model. In a first time the chapter IV focus on the theory of the magnetism and magnetics materials. In a second time, we present the magnetic characterization of the materials used in the electromagnetics flowmeters. In the chapter V, an introduction to the numerical modelling is done in order to justify the using of the finite element method for the magnetic simulation on the software NX Nastran. The second part of this chapter concerns the development and the numerical simulation of an electromagnetic flowmeter. At last, the third part is about the installation of a test bed to measure the magnetic field produced inside the electromagnetic flowmeter and to compare the results with the simulation. Numerical simulation of the magnetic field being checked by the measurements, the next chapter introduces molecular dynamics of the charged particles inside the measuring pipe in order to compute electrical potential. Finally, the last part introduces the calibration of electromagnetics flowmeters where a theoretical model was developed in order to compare them with experimentals values measured in production on Haguenau Siemens site
Risso, Frédéric. "Déformation et rupture d'une bulle dans une turbulence diffusive". Toulouse, INPT, 1994. http://www.theses.fr/1994INPT103H.
Texto completoDechriste, Guillaume. "Méthodes numériques pour la simulation d'écoulements de gaz raréfiés autour d'obstacles mobiles". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0388/document.
Texto completoThis work is devoted to the multidimentional simulation of rarefied gases in a domain with moving boundary. The governing equation is given by BGKtype model of Boltzmann equation and velocity space is discretized with a standard discrete velocity method.We first propose three space discretizations that take boundary motion into account by specific treatment of the boundary conditions. These approaches are implemented and validated for several 1D flows. Based on this study, the cut cell method is chosen to be extend to multidimentional flows.Then we detail the cut cell algorithm for 2D and 3D flow simulations. Robustness and accuracy of the implementation are investigated through the simulation of numerous test cases. Our results are rigorously compared to the ones coming from the literature and good agreement is shown. The cut cell method has been optimized with an adaptive refinement mesh technique. The 3D unstationary simulation of the Crookes radiometer rotating vanes is a perfect illustration of the method potential
Vaudor, Geoffroy. "Atomisation assistée par un cisaillement de l'écoulement gazeux. Développement et validation". Rouen, 2015. http://www.theses.fr/2015ROUES024.
Texto completoAssisted atomization enables to transform a liquid jet into drops using a co-flowing high-speed gas jet. This method is applied in cryogenic engines and aircraft propulsion systems. However, numerical study of these configurations is challenging, due to the high shearing associated with the high density ratio between the liquid and gaseous phases, which make most solvers unstable, including the ARCHER solver developed in CORIA laboratory. Numerical developments on the modeling of the convective term based on Rudman's work have been performed. The main idea is to re-establish the consistency between numerical mass and momentum transport. The original discretization requires moving the interface onto a dual grid. This method has proved to be stable but numerically costly. A new discretization which enables to get rid of the second grid is suggested and validated on different test cases. Experimental studies on assisted atomization have been carried out in LEGI laboratory for years and the new numerical scheme developed during these studies have enabled to simulate numerically a 2D sheared liquid film and a coaxial liquid jet in 3D, which have then been compared to the experimental results
Troadec, François. "Simulation numérique directe d'un écoulement supercritique pour validation des approches RANS et LES". Rouen, 2010. http://www.theses.fr/2010ROUES043.
Texto completoThe main aim of this work is to develop tools able to realise numerical simulation of cryogenic flows by proposing tests case based on numerical experiments through the use of Direct Numerical Simulation (DNS). Many problems encountered during experiments are due to experimental conditions (high pressure and very flammable reactives) that impose researchers to consider new numerical ways. Indeed, beyond a given pressure, the distinction between liquid and gaseous phase disappears and molecular interactions can’t be neglected anymore. This affects thermo-physical variables. So, different physical models have been studied and results have been compared to reference data (NIST). Some of them have been introduced in Asphodele solver. This solver is based on a low Mach number formulation. The reference configuration used simulates the destabilization of a jet in supercritical condition. Main aim being to reach conditions present inside the rocket’s combustion chamber and to test low Mach number formulation applied in supercritical flows. Finally, from results extracted from DNS simulation, a priori tests are used to study RANS and LES terms modelisation like the mixture fraction formulation (RANS) and the use of filtered variable in equation of state (LES)
Bizid, Wided. "Développement de méthodes de pénalisation pour la simulation de l’écoulement turbulent autour d’obstacles". Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0631/document.
Texto completoIn the perspective of application to wind turbine design, this thesis aims to extend theuse of fictitious domain methods and in particular the method of penalization for the simulation of unsteady turbulent flows around obstacles of complex geometry. The unsteady turbulence modeling at high Reynolds numbers was studied by hybrid approaches(RANS / LES) such as (DES) and (DDES). In order to improve the prediction, a wall model based on simplified Thin Boundary Layer Equations (TBLE) was introduced.After a brief presentation of the tools and methods implemented, full 2D / 3D computations on cylinder and channel configuration are then presented, analyzed and compared to numerical and experimental results.The simulation results show the feasibility and effectiveness of the proposed models and the coupling method (DDES / TBLE).The latest investigation focuses on the simulation of the flow around the airfoil of a wind turbine. The success and fails of the computations are highlighted and explained
Benguigui, William. "Modélisation de la réponse dynamique d’une paroi solide mise en vibration par un écoulement fluide diphasique". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLY014.
Texto completoIn nuclear power plants, steam generator tubes vibrate because of steam/water cross-flows. In order to understant this phenomenon, reduced-scale experiments are performed. Numerical simulations have shown their ability to accurately reproduce the vibration induced by a single phase flow in a tube bundle. The aim of the present work is to do the same with two-phase flow and to characterize the effect of the mixture physical properties on vibration.To do so, a CFD code based on a two-fluid approach is used. A "discrete forcing" method is implemented in order to allow solid body motion in a two-phase flow. The validation is performed with simple and industrial cases using experimental and theoretical results.Using an existing implicit algorithm, a fluid-structure coupling based on the developed interface tracking method is implemented. Validated for single and two-phase flows, it is now possible to have solid motion induced by fluid forces.The different numerical models dedicated to two-phase flows are then evaluated on a freon/freon flow across an inclined tube bundle. The use of a multi-regime model is required. In order to investigate the role of the different physical properties on the vibration, three simple studies are performed.Finally, the industrial application, a freon/water flow across a square pitch tube bundle, is performed. First, it is compared to a steam/water flow in order to characterize the discrepancies when we are using a modeling mixture. Then, the vibration induced by single- and two-phase flows is reproduced by the developed method on feasibility test cases
Buffat, Marc. "Étude de la simulation numérique par une méthode d'éléments finis des écoulements internes subsoniques instationnaires bi et tridimensionnels". Lyon 1, 1991. http://www.theses.fr/1991LYO10002.
Texto completoBenguigui, William. "Modélisation de la réponse dynamique d’une paroi solide mise en vibration par un écoulement fluide diphasique". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLY014/document.
Texto completoIn nuclear power plants, steam generator tubes vibrate because of steam/water cross-flows. In order to understant this phenomenon, reduced-scale experiments are performed. Numerical simulations have shown their ability to accurately reproduce the vibration induced by a single phase flow in a tube bundle. The aim of the present work is to do the same with two-phase flow and to characterize the effect of the mixture physical properties on vibration.To do so, a CFD code based on a two-fluid approach is used. A "discrete forcing" method is implemented in order to allow solid body motion in a two-phase flow. The validation is performed with simple and industrial cases using experimental and theoretical results.Using an existing implicit algorithm, a fluid-structure coupling based on the developed interface tracking method is implemented. Validated for single and two-phase flows, it is now possible to have solid motion induced by fluid forces.The different numerical models dedicated to two-phase flows are then evaluated on a freon/freon flow across an inclined tube bundle. The use of a multi-regime model is required. In order to investigate the role of the different physical properties on the vibration, three simple studies are performed.Finally, the industrial application, a freon/water flow across a square pitch tube bundle, is performed. First, it is compared to a steam/water flow in order to characterize the discrepancies when we are using a modeling mixture. Then, the vibration induced by single- and two-phase flows is reproduced by the developed method on feasibility test cases
Medale, Marc. "Modélisation numérique de l'étape de remplissage des moules de fonderie par la méthode des éléments finis". Compiègne, 1994. http://www.theses.fr/1994COMPD714.
Texto completoAl, Isber Aziz. "Modélisation de l'écoulement instationnaire décollé à la traversée d'un diaphragme par la méthode des vortex aléatoires". Toulouse, ENSAE, 1991. http://www.theses.fr/1991ESAE0002.
Texto completoMorente, Antoine. "Développement d'une méthode de pénalisation pour la simulation d'écoulements liquide-bulles". Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19922/1/MORENTE_Antoine.pdf.
Texto completoZhong, Guoming. "Contribution à l'étude de l'adsorption dans une colonne : modélisation et simulation numérique". Compiègne, 1991. http://www.theses.fr/1991COMPD373.
Texto completoDuarte, Max. "Méthodes numériques adaptatives pour la simulation de la dynamique de fronts de réaction multi-échelles en temps et en espace". Phd thesis, Ecole Centrale Paris, 2011. http://tel.archives-ouvertes.fr/tel-00667857.
Texto completoCunha, Guilherme. "Optimisation d'une méthodologie de simulation numérique pour l'aéroacoustique basée sur un couplage faible des méthodes d'aérodynamique instationnaire et de propagation acoustique". Thesis, Toulouse, ISAE, 2012. http://www.theses.fr/2012ESAE0028/document.
Texto completoThe present work consisted in improving, assessing and validating further the CFD/CAA surface weak coupling methodology, with respect to its application to realistic problems of aircraft noise. In particular, it was here shown how far such hybrid methodology could (i) cope with all stringent constraints that are dictated by real-life applications, (ii) without being jeopardized by some of the unavoidable side-effects (such as the signal degradation to which CFD data are subjected, when processed or being then acoustically exploited)