Dissertationen zum Thema „Équation des milieux poreux“
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Baudry, Cécile. „Des invariants pour une équation elliptique-parabolique des milieux poreux : étude théorique et applications numériques“. Paris 13, 2010. http://www.theses.fr/2010PA132006.
Der volle Inhalt der QuelleIn this thesis, we study some invariants for selfsimilar solutions of an elliptic-parabolic equation, which is used for the modelling of water flows in saturated-unsaturated porous medium. We look into intermediate asymptotics, in space and in time, for Richards’ equation in 1D in a semi-infinite domain. At the initial time, a finite part is saturated and an infinite one is unsaturated. Indeed, selfsimilar solutions are solutions of problems with specific initial and boundary conditions. According to Barenblatt and Zel’dovich, these selfsimilar solutions are also good approximations of more general problems, with different boundary or initial conditions. Then selfsimilar solutions are called respectively intermediate asymptotics in space and in time for the general problem. We can do these approximations if the general problem and the selfsimilar problem check the same invariant. We underline it is only a necessary condition. This manuscript is divided into six chapters. The first one recalls the physics of the problem. The second and the third chapters deal with the theoretical and numerical aspects of a special case: the heat equation. The last three chapters concern Richards’ equation; we study intermediate asymptotics in space and in time after a bibliography about existence and unicity for this equation
Belaribi, Nadia. „Aspects probabilistes et numériques relatifs à une équation de type milieux poreux à coefficients irréguliers“. Paris 13, 2012. http://scbd-sto.univ-paris13.frintranet/edgalilee_th_2012_belaribi.pdf.
Der volle Inhalt der QuelleThe main object of this thesis is an evolution problem in L1(Rd) of the type ∂tu(t, x) =1/2xΔβ(u(t, x)), (t, x) ∈ ]0, T ] × Rexpd. (PDE). In our work, we have investigated some theoretical complements related to the (probabilistic) representation of that equation, via a non-linear diffusion process, when the coefficient β is discontinuous or in the case β(u) = um, 0 < m < 1 (“fast diffusion equation”). Even though the theoretical results concern essentially dimension d = 1, we have also establi- shed a uniqueness theorem for a multidimensional Fokker-Planck type with measurable, possibly unbounded and degenerated coefficients. This has been an important tool for the probabilistic representation. We have also established some density estimates (via Malliavin calculus) of the solution of an SDE with smooth unbounded coefficients, with bounded derivatives of each order, uniformly with respect to the initial condition. The main objective of the thesis consists however in the implementation of an interactive particle system algorithm, which approaches the solutions of the PDE. Comparison with recent deterministic numerical techniques have been performed. This has been done in the one dimensional and multidimensional cases
Zeltz, Eric. „Modélisations d'injections multiphasiques en milieux poreux“. Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0027/these.pdf.
Der volle Inhalt der QuelleBy using the mathematical techniques of homogenization and by starting from the Navier-Stokes equations, we model the injection of fuids in porous medium in three different cases. - First, in the case of a compressible fluid: we recover the model of Aronson. -then in the case of an incompressible fluid injected in the porous medium filled with another incompressible fluid. We demonstrate that the interface is determined by a problem of Riemann and that its average speed is linear. We show that the nature of the interface is essentially de fined by the coefficient of mobility of both fluids. We validate the model thanks to an experience of injection of resin in a porous medium. We use our model to interpret a known physical phenomenon but in our knowledge never explained in satisfactory way: the headway of the interface along the walls of the porous mould in the case of the injection of a very sticky fluid. - Finally we consider the previous case when the injected uid is condensable. We demonstrate again that the interface is determined by a Riemann problem but that its speed goes asymptotically towards zero. We validate our model with an experience of vapor injected in some concrete. We give a new explanation to a phenomenon classically called " phenomenon of cork " and observed in this type of experience
Chmaycem, Ghada. „Étude des équations des milieux poreux et des modèles de cloques“. Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1080/document.
Der volle Inhalt der QuelleIn this thesis, we study two completely independent problems. The first one focuses on a simple mathematical model of thin films delamination and blistering analysis. In the second one, we are interested in the study of the porous medium equation motivated by seawater intrusion problems. In the first part of this work, we consider a simple one-dimensional variational model, describing the delamination of thin films under cooling. We characterize the global minimizers, which correspond to films of three possible types : non delaminated, partially delaminated (called blisters), or fully delaminated. Two parameters play an important role : the length of the film and the cooling parameter. In the phase plane of those two parameters, we classify all the minimizers. As a consequence of our analysis, we identify explicitly the smallest possible blisters for this model. In the second part, we answer a long standing open question about the existence of new contractions for porous medium type equations. For m>0, we consider nonnegative solutions U(t,x) of the following equationU_t=Delta U^m.For 0
Ene, Ioana-Andreea. „Etude de quelques problèmes d'écoulement dans les milieux poreux“. Metz, 1995. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1995/Ene.Ioana_Andreea.SMZ9553.pdf.
Der volle Inhalt der QuelleThe aim of this thesis is the study of two problems of flow through porous media. In the first and the second chapter we study in the general framework of the homogenization method the flow of a viscous fluid through an elastic thin porous media. After the proof of the convergence of the homogenization process by using the two-scale convergence method it is possible to take the limit as the second small parameter (who caracterize the thickness of the solid part) tends to zero. We obtain a viscoelastic media with fading memory. We consider the two classical cases, when we have a Stokes flow in the fluid part and when we have a Navier-Stokes flow in the fluid part. In the third chapter we study a double porosity model in a double periodicity media. From a mechanical point of view this model represents a fracturated porous media. From a mathematical point of view we study a Neumann problem with double periodicity. We prove existence and unicity for such a problem and using the three-scale convergence method we obtain the homogenized equation and the homogenized coefficients. The result we obtain is a Darcy law at the macroscale and this show us that, at least in the steady case, both the double periodicity model and the double porosity model are the same
Lyaghfouri, Abdeslem. „Sur quelques problèmes d'écoulement dans les milieux poreux“. Metz, 1994. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1994/Lyaghfouri.Abdeslem.SMZ9428.pdf.
Der volle Inhalt der QuelleIn this work, we study fluid flows through a porous medium with leaky boundary conditions. In the first chapter, the fluid is governed by a linear Darcy's low. The second chapter is about a unbounded dam. In the third chapter, we extend our results to the case of a maximal monotone graph. In the last chapter, the fluid is governed by a nonlinear Darcy's low. In this thesis, we investigate questions of existence, uniqueness and shape of the free boundary
Ondami, Bienvenu. „Sur quelques problèmes d'homogénéisation des écoulements en milieux poreux“. Pau, 2001. http://www.theses.fr/2001PAUU3002.
Der volle Inhalt der QuelleKelanemer, Youcef. „Transferts couplés de masse et de chaleur dans les milieux poreux : modélisation et étude numérique“. Paris 11, 1994. http://www.theses.fr/1994PA112060.
Der volle Inhalt der QuelleEl, Ossmani Mustapha. „Méthodes Numériques pour la Simulation des Ecoulements Miscibles en Milieux Poreux Hétérogènes“. Phd thesis, Université de Pau et des Pays de l'Adour, 2005. http://tel.archives-ouvertes.fr/tel-00009683.
Der volle Inhalt der QuelleMaarouf, Sarra. „Discrétisation spectrale du transfert de chaleur et de masse dans un milieu poreux“. Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066133/document.
Der volle Inhalt der QuelleThis thesis aims to show that the numerical simulation of heat and mass transfer in porous media can be effectively treated by a numerical program which is based on a space discretization of spectral type. The spectral method is optimal in the sense that the error obtained is only limited by the regularity of the solution. The starting point of this study is the system of nonlinear unsteady Darcy equations that models the unsteady flow of a viscous fluid in a porous medium when the permeability of the medium depends on the pressure. The second problem which we study models transfer of heat in a porous medium which is described by Darcy equations coupling with the heat equation. In the last part, the concentration of mass is taken into account in the medium, we describe a nonlinear problem that models unsteady transfer of heat and mass in porous media. In the three proposed problems, the results of the existence and the uniqueness are established. Then the corresponding discrete problems are described. We prove the error a priori estimates and we confirm the theoretical study with numerical results
Marusic-Paloka, Eduard. „Modélisation par homogénéisation des écoulements en milieux poreux fissurés“. Saint-Etienne, 1995. http://www.theses.fr/1995STET4008.
Der volle Inhalt der QuelleFabrie, Pierre. „Contribution à l'étude de la convection naturelle en milieux poreux“. Bordeaux 1, 1987. http://www.theses.fr/1987BOR10631.
Der volle Inhalt der QuelleJimenez, Julien. „Modèles non linéaires de transport dans un milieu poreux hétérogène“. Phd thesis, Université de Pau et des Pays de l'Adour, 2007. http://tel.archives-ouvertes.fr/tel-00204610.
Der volle Inhalt der QuelleEn premier lieu nous considérons un problème couplé hyperbolique/hyperbolique. Sous une condition de non dégénérescence du flux, nous avons obtenu un résultat d'existence et d'unicité d'une solution faible entropique d'abord en dimension 1 d'espace puis en dimension quelconque. La preuve de l'unicité est basée sur la méthode de dédoublement des variables due à S.N. Kruzkov puis sur un raisonnement presque partout à l'interface. Dans le cas particulier de la dimension 1 l'existence s'obtient par une régularisation adéquate du coefficient discontinu dans le terme de convection alors que nous utilisons la méthode de viscosité artificielle dans le cas général.
En second lieu nous traitons le cas de termes de convection qui apparaissent dans l'ingénierie pétrolière pour lesquels la condition de non dégénérescence de la non linéarité n'est pas vérifiée. Nous ne pouvons donc pas adapter les méthodes précédemment utilisées. Nous nous sommes donc intéressés à un problème couplé perturbé où sur l'un des deux ouverts un terme de diffusion est ajouté. Sous l'hypothèse que les caractéristiques provenant de la zone hyperbolique sont sortantes à l'interface, l'unicité d'une solution faible entropique est établie. La méthode de viscosité artificielle et la notion de processus entropique nous permettent de prouver le résultat d'existence .
Berbiche, Amine. „Propagation d'ondes acoustiques dans les milieux poreux fractals“. Electronic Thesis or Diss., Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4758.
Der volle Inhalt der QuelleThe action integral minimization method (variational principle) provides the wave propagation equations. This method has been generalized to fractal dimensional porous media to study the acoustic propagation in the time domain, based on the equivalent fluid model. The resulting equation rewritten in the frequency domain represents a generalization for the Helmholtz equation. As part of the Allard-Johnson model, the propagation equation was solved analytically in the time domain, for both high and low frequencies fields. The resolution was made by the method of the Laplace transform, and focused on a semi-infinite porous medium. It was found that the wave velocity depends on the fractal dimension.For a fractal porous material of finite thickness which receives an acoustic wave at normal incidence, the Euler conditions were used to determine the reflected and transmitted fields. The resolution of the direct problem was made in the time domain by the method of the Laplace transform, and through the use of the Mittag-Leffler functions. The inverse problem was solved by the method of minimizing the least squares sense. Tests have been performed successfully on experimental data; programs written from the formalism developed in this work have allowed finding the acoustic parameters of porous foams, in the fields of high and low frequencies
Mchirgui, Walid. „Modélisation des transferts hydriques dans les milieux poreux partiellement saturés par homogénéisation périodique : Application aux matériaux cimentaires“. Thesis, La Rochelle, 2012. http://www.theses.fr/2012LAROS365/document.
Der volle Inhalt der QuelleWe propose in this work to construct, by periodic homogenization, macroscopic models of moisture transfer in unsaturated porous media. To do this, the liquid water and water vapor transport equations are averaged from the microscopic scale. The dimensional analysis of transport equations naturally lets appear dimensionless numbers characterizing the moisture transfer in unsaturated porous media. Three different transfer regimes are addressed (predominant water vapor diffusion, coupling diffusion / convection, predominant liquid water convection). For each transfer regime, the associated homogenized moisture diffusion tensor has a different expression. Then, the homogenized moisture diffusion tensors are calculated in both hygroscopic and super-hygroscopic regions on several geometries with varying complexity, describing 2D and 3D microstructures. Comparisons with experimental values are also addressed. Finally, based on experimental data of a BHP concrete, a numerical resolution of the homogenized macroscopic moisture transfer equation is performed
Oukfif, Samira. „Modélisation numérique du transport de masse et de la filtration dans les milieux poreux saturés“. Le Havre, 2010. http://www.theses.fr/2010LEHA0007.
Der volle Inhalt der QuelleThis work aims is devoted to the development of numerical model in order to simulate the mass transport in homogeneous and heterogeneous porous media. So to guarantee security, a reliable numerical model will be used at long term to predict the progression of pollution in a ground. The model is based on the convection-dispersion equation coupled with a deposition release kinetic. The transport equation in 1D and 2D is resolved by means of a Lagrangian method, called particle method which uses a dispersion velocity technique. The boundary conditions are interpreted with a technique of a ghost particle. Due to the retention and detachment of the particle, the Kozeny-Carman relation is employed to evaluate the porosity variation in the porous media. The sensitivity study of the model is performed by considering a various configurations when analytical solutions are provided and shows a sufficient precision for adequate numerical parameters. The numerical model validation is obtained by fitting the tracer laboratory column under the constant flow or constant flow head conditions. Under the constant flow head, a coupling between the transport equation and flow equation (Darcy’s low) are performed by resolving flow equation using a numerical model of the finite differences on a fixed grid. The coupling between the flow problem and the transport problem is realized with using a non iterative sequential scheme. The exchanges between the grid and the particles are ensured by means of interpolation function. A good fitting is obtained from the numerical results and experiment data measured in the term of breakthrough curves, in particular when the deposition and release kinetic were considered. The constant flow head shows an important reduction of the porosity profiles at the entry of the laboratory column. Then, the numerical model is used to simulate the erosion (suffusion) of a ground by considering only release, and the fitting of the laboratory column showed a good agreement. An interesting alternative to particle tracking random walk random is studied in order to simulate the transport of sorbing solutes in homogeneous and heterogeneous infinite media. The deposition release kinetic is replaced by a nonlinear Freundlich sorption is considered. A stochastic approach which consists in generating many simulations for which flow and transport problems are resolved. The final results are obtained by means of an average on all numerical simulations performed called Monte Carlo approach. The results obtained are in agreement with those presented in the literature. In order to simulate transport, deposition and release in a finite porous media, the numerical model presented in this study allowed the implementation of the particle method. Nevertheless, the model studied of the deposition and release kinetic can be improved in order to take account the coupling between the two processes and in particular the threshold of detachment of the particles
Berbiche, Amine. „Propagation d'ondes acoustiques dans les milieux poreux fractals“. Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4758.
Der volle Inhalt der QuelleThe action integral minimization method (variational principle) provides the wave propagation equations. This method has been generalized to fractal dimensional porous media to study the acoustic propagation in the time domain, based on the equivalent fluid model. The resulting equation rewritten in the frequency domain represents a generalization for the Helmholtz equation. As part of the Allard-Johnson model, the propagation equation was solved analytically in the time domain, for both high and low frequencies fields. The resolution was made by the method of the Laplace transform, and focused on a semi-infinite porous medium. It was found that the wave velocity depends on the fractal dimension.For a fractal porous material of finite thickness which receives an acoustic wave at normal incidence, the Euler conditions were used to determine the reflected and transmitted fields. The resolution of the direct problem was made in the time domain by the method of the Laplace transform, and through the use of the Mittag-Leffler functions. The inverse problem was solved by the method of minimizing the least squares sense. Tests have been performed successfully on experimental data; programs written from the formalism developed in this work have allowed finding the acoustic parameters of porous foams, in the fields of high and low frequencies
Trégarot, Gildas. „Modélisation couplée des écoulements à saturation variable avec hétérogénéités, forçages, et interfaces hydrologiques“. Toulouse, INPT, 2000. http://www.theses.fr/2000INPT010H.
Der volle Inhalt der QuelleBarrère, Jean. „Modélisation des écoulements de Stokes et Navier-Stokes en milieux poreux“. Bordeaux 1, 1990. http://www.theses.fr/1990BOR10516.
Der volle Inhalt der QuelleGipouloux, Olivier. „Contribution numérique à l'homogenéisation des équations de Stokes et de Navier-Stokes en milieux poreux“. Bordeaux 1, 1992. http://www.theses.fr/1992BOR10534.
Der volle Inhalt der QuelleEl, Ossmani Mustapha. „Méthodes numériques pour la simulation des écoulements miscibles en milieux poreux hétérogènes“. Pau, 2005. http://www.theses.fr/2005PAUU3005.
Der volle Inhalt der QuelleIn this thesis, we are interested in numerical methods for a model of incompressible and miscible flows having application in hydrogeology and oil engineering. We study and analyze a numerical scheme combining a mixed finite element method (MFE) and a finite volumes method (FV) to discretize the coupled system between an elliptic equation (pressure-velocity) and a convection-diffusion-reaction equation (concentration). The FV scheme considered is "vertex centred" type semiimplicit in time: explicit for the convection and implicit for the diffusion. We use a Godunov scheme to approach the convectif term and a P 1 finite element approximation for the diffusion term. We prove that the FV scheme is La and BV stable and satisfy the discrete maximum principle under a suitable CFL condition. Then, we show the convergence of the approximate solution obtained by the combined scheme MFE-FV towards the solution of the coupled problem. The proof of convergence is done in several steps : first we deduce strong convergence of the approximate solution in L2(Q), using La stability, BV estimates and a compactness argument. In the second step we study the decoupled MFE scheme, by giving a convergence result for the pressure and velocity. In the final step, the process of convergence of the approximate solution of the combined scheme MFE-FV towards the exact solution is obtained by passing in the limit and uniqueness of the solution of the continuous problem. . . Finally, we analyze a residual error estimator for a convection-diffusion-reaction equation discretized by a semi-implicit finite volume. We introduce two kinds of indicators. The first is local in time and space and constitutes an effective tool for the adaptation of the grid to each time step. The second is total in space but local in time and can be used for the adaptation in time. The error etimators with respect to both time and space yield global upper and local lower bounds on the error measured in the energy norm. Numerical results of adaptations of grid are presented and show the effectiveness of the method. The software part of this work concerns two shutters. The first allowed to carry out an IMPES simulator, MFlow, written in C++, for the simulation of the system of miscible flows considered in this thesis. The second shutter relates to the collaboration with a group of researchers for the development of the Homogenizer++ platform realized within the framework of the GDR MoMaS (http://momas. Univ-lyon1. Fr/)
Mchirgui, Walid, und Walid Mchirgui. „Modélisation des transferts hydriques dans les milieux poreux partiellement saturés par homogénéisation périodique : Application aux matériaux cimentaires“. Phd thesis, Université de La Rochelle, 2012. http://tel.archives-ouvertes.fr/tel-00823902.
Der volle Inhalt der QuelleFontaine, Vincent. „Quelques méthodes numériques robustes pour les modèles de transfert diffusif en milieu poreux“. La Réunion, 2008. http://elgebar.univ-reunion.fr/login?url=http://thesesenligne.univ.run/08_17-fontaine.pdf.
Der volle Inhalt der QuelleIn this dissertation, our focus is on the well-known class of elliptic/parabolic boundary value problems, namely the second order diffusion equation, usually used to model mass transfer in porous media. We discuss the Mixed Finite Element (MFE) methods and its hybridization technique and families of flux-continuous schemes referred in the literature as Multi-Point Flux Approximation (MPFA) methods. MFE and MPFA methods are well suited for the resolution of this prototype equation since both approaches are locally conservative, handle easily unstructured grids and heterogeneous / discontinuous media. Low order MFE methods are considered in this work using either finite elements of Raviart-Thomas or Brezzi-Douglas-Marini. The family of flux-continuous schemes is presented in the physical space and reference space, and has been performed for a large range of quadrature points. Motivated by MPFA formulation, a Multipoint version of Mixed Finite Element (MPMFE) method that reduces to cell-centered finite differences is investigated on quadrilateral and simplicial grids that performs well for discontinuous full tensor coefficients. The link between MPMFE and MPFA formulations is show algebraically for the lowest order finite elements of Raviart-Thomas and of Brezzi-Douglas-Marini. The different tests carried out in anisotropic and heterogeneous media show the computational superiority of the MPMFE approximation
Guellouz, Sami. „Modélisation de la migration de colloïdes dans un milieu poreux“. Phd thesis, Ecole Nationale des Ponts et Chaussées, 1994. http://tel.archives-ouvertes.fr/tel-00529457.
Der volle Inhalt der QuelleVu, Minh Ngoc. „Modélisation des écoulements dans des milieux poreux fracturés par la méthode des équations aux intégrales singulières“. Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1168/document.
Der volle Inhalt der QuelleThis thesis aims to develop a method for numerical modelling of fluid flow through fractured porous media and for determination of their effective permeability by taking advantage of recent results based on formulation of the problem by Singular Integral Equations. In parallel, it was also an occasion to continue on the theoretical development and to obtain new results in this area. The governing equations for flow in such materials are reviewed first and mass conservation at the fracture intersections is expressed explicitly. Using the theory of potential, the general potential solutions are proposed in the form of a singular integral equation that describes the steady-state flow in and around several fractures embedded in an infinite porous matrix under a far-field pressure condition [136, 139]. These solutions represent the pressure field in the whole body as functions of the infiltration in the fractures, which fully take into account the fracture interaction and intersections. Closed-form solutions for the fundamental problem of fluid flow around a single fracture are derived, which are considered as the benchmark problems to validate the numerical solutions. In particular, the solution obtained for the case of an elliptical disc-shaped crack obeying to the Poiseuille's law has been compared to that obtained for ellipsoidal inclusions with Darcy's law [140].The numerical programs have been developed based on the singular integral equations method to resolve the general potential equations [132, 180]. These allow modeling the fluid flow through a porous medium containing a great number of fractures. Besides, this formulation of the problem also allows obtaining a semi-analytical infiltration solution over a single fracture depending on the matrice permeability, the fracture conductivity and the fracture geometry. This result is the important key to upscalling the effective permeability of a fractured porous medium by using different homogeneisation schemes. The results obtained by the self-consistent scheme have been in particular established. The multi-region approach can be used to extend the general potential solution written for the infinite domain to that for a finite domain [181]. A closed-form solution for flow in and around a single partially saturated fracture, surrounded by an infinite matrix subjected to a far-field condition, is also derived combining the solutions for a superconductive fracture and for an imprevious fracture. This solution is then employed to estimate the effective permeability of unsaturated fractured porous media [141].The effective permeability model is applied to study the hydromechanical behaviour of a fault zone constituted by a clay core surrounded by fractured zones in the context of CO2 geological storage. The pressure injection induces an overpressure in the reservoir that may affect the permeability of the fractured zones leading to complexe coupled hydromechanical phenomena. The simulation results allow evaluating the risk of leakage of the reservoir brine to higher aquifers as well as the risk of fault reactivation
Vu, Minh Ngoc, und Minh Ngoc Vu. „Modélisation des écoulements dans des milieux poreux fracturés par la méthode des équations aux intégrales singulières“. Phd thesis, Université Paris-Est, 2012. http://pastel.archives-ouvertes.fr/pastel-00777926.
Der volle Inhalt der QuelleCompère, Fabrice. „Transport et rétention de particules argileuses en milieu poreux saturé : approches expérimentales et numériques“. Poitiers, 1999. http://www.theses.fr/1999POIT2301.
Der volle Inhalt der QuelleMejni, Fatah. „Structures synchronisées dans les écoulements inhomogènes de convection mixte en milieux poreux“. Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10071/document.
Der volle Inhalt der QuelleMixed convection flow in porous media heated from below non uniformly and subjected to an horizontal pressure gradient is studied theorettcally and numericalIy. The prescribed temperature at the bottom boundary is assumed to vary slowly in space. The result is the establishment of a weak inhomogeneous basic state, the stabIllty of which is carried out using the WKBJ approximation. Depending on the choice of the imposed inhomogeneous temperature profile, two cases prove to be of interest: the base flow displays an absolute instability region either detached from the inlet or attached to it. Results from combined direct numerical simulations and limear stability approach have revealed that in the first case, the nonlinear solution is a steep nonlinear global mode, with a sharp stationary front located at a margimally absolutely unstable station. ln the second configuration, the scaling laws for the establishment of a nonlmear global mode quenched by the inlet are found to perfectly agree with the theory. It is also found that in both configurations, the global frequency of synchronized oscillations corresponds to the local absolute frequency determined by Iinear criterion, even far from the threshold of global instability. All these results agree remarkably with recent advances of nonlinear global modes theory, A good agreement is also found between the predictions of the theory and the measured global frequencies
Oumouni, Mestapha. „Analyse numérique de méthodes performantes pour les EDP stochastiques modélisant l'écoulement et le transport en milieux poreux“. Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00904512.
Der volle Inhalt der QuelleKrepysheva, Natalia. „Transport anormal de traceurs passifs en milieux poreux hétérogènes : équations fractionnaires, simulation numérique et conditions aux limites“. Avignon, 2005. http://www.theses.fr/2005AVIG0502.
Der volle Inhalt der QuelleIn a number of disordered porous, solute spreading does not obey Fick's law. The latter describes the evolution of a plume of tracer. When initial data represent a local impulse, the concentration is a Gaussian variance is proportional to time. Experimental data obtained in aquifers have put into evidence qualitatively different behaviors, replacing Gaussians by stable Lévy densities, which also are non increasing functions. But in the large values asymptotics, they behave algebraically, and in general the second moment does not converge. Moreover, stable Lévy densities are the fundamental solutions of a wide class of partial differetial equations, which are space-fractional equations. They resemble heat equation, with the Laplacean being replaced by a derivative of non-integer order. They also rule the evolution of the concentration of a cloud of random walkers performing Lévy flights, wich are more general than Brownian motion, with the jump length density being a stable Lévy law. All these point are detailed in the thesis. The main results concern the spreading of matter in a semi-infinite medium where the motion of tracer particles is described by Lévy flights (on the small scale) except when they meet the boundary. With a reflexive wall, it is necessary to modify the kernel of the fractional derivative on the right hand-side of the equation ruling the evolution of the concentration of walkers. The theoretical result is illustrated by a Monte Carlo simulation, and compared with the numerical discretization of the fractional equation in a semi-infinite medium
Guellouz, Sami. „Modélisation de la migration de colloïdes dans un milieu poreux“. Phd thesis, Marne-la-vallée, ENPC, 1994. http://www.theses.fr/1994ENPC9431.
Der volle Inhalt der QuelleDelache, Alexandre. „Étude analytique et numérique des instabilités spatio-temporelles des écoulements de convection mixte en milieux poreux : comparaison avec l'expérience“. Lille 1, 2005. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2005/50376-2005-Delache.pdf.
Der volle Inhalt der QuelleVu, Thanh Long. „Modélisations et simulations numériques d'écoulements d'air dans des milieux micro poreux“. Phd thesis, Université Paris-Est, 2011. http://tel.archives-ouvertes.fr/tel-00679375.
Der volle Inhalt der QuelleKaczmaryk, Anne. „Approches multi-continuum de la dualité homogénéisation-inversion des propriétés hydrodynamiques en milieu poreux fracturé“. Poitiers, 2008. http://theses.edel.univ-poitiers.fr/theses/2008/Kaczmaryk-Anne/2008-Kaczmaryk-Anne-These.pdf.
Der volle Inhalt der QuelleThe quite-systematic scarcity of sampled data hampers the study of underground media. This is why the question remains of getting suited interpretations based on in situ data to evaluate macroscopic parameters ruling flow and mass transport in underground reservoirs. The aim of this work is to invert dynamic data by means of tools with a physical view on the reservoir functioning (opposed here to a systemic approach). Hydraulic interference testing has been held in two campaigns over the fractured limestone aquifer of the Hydrogeological Experimental Site (HES) in Poitiers (France). Drawdown data are interpreted by enhanced dual-medium approaches, with special care given to karstic draining observed on data of the second campaign. A tool for mass transport inversion is also developed with calculations handled by a Lagrangian approach in time over bond networks. Among various refinements, inversion is coupled with an analytical derivation of the model sensitivity to parameters. Finally, the trace of the network is eliminated by substituting the classical transport equations by the Langevin equations. The latter include a force field yielding a hyperbolic term that would mimic the eventual channelling effects of a network. Several analytical developments of the mean displacement and dispersion of particles, both in transient and asymptotic context, testify that the substitution is feasible. This work should be pursued however, for instance by addressing with the tools mentioned above field tracer test experiments carried out in various contexts
Verdière, Sophie. „Méthodes numériques de double maillage pour la simulation d'écoulements polyphasiques dans les milieux poreux“. Pau, 1997. http://www.theses.fr/1997PAUU3004.
Der volle Inhalt der QuelleGemelli, Fabrizio. „Modélisation de l'endommagement pour les milieux poreux saturés : une approche multi-échelle“. Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENI113/document.
Der volle Inhalt der QuelleThis work presents the constitutive modeling of a geomaterial consisting of a deformableand saturated porous matrix including a periodic distribution of evolving fluid-filledcavities. The homogenization method based on two-scale asymptotic developments isused in order to deduce a model able to describe the macroscopic hydro-mechanicalcoupling. By taking into account the cavity growth and without any phenomenologicalassumption, it is proposed a mesoscopic energy analysis coupled with the homogenizationscheme which provides a damage evolution law. In this way, a direct link between themeso-structural fracture phenomena and the corresponding macroscopic damage isestablished. Lastly, a numerical study of the local macroscopic hydro-mechanical damage behaviour is presented
In questa tesi si presenta la modellazione costitutiva di un geomateriale composto da unamatrice porosa satura e deformabile contenente una distribuzione periodica di cavitàriempite da fluido che si propagano. Il metodo di omogeneizzazione basato sugli sviluppiasintotici a doppia scala viene utilizzato con l'obiettivo di dedurre un modello capace didescrivere l'accoppiamento idro-meccanico macroscopico. Prendendo in considerazione lapropagazione delle cavità e senza nessuna ipotesi fenomenologica, si propone un'analisienergetica mesoscopica accoppiata ad uno schema di omogeneizzazione che fornisce unalegge di evoluzione del danno.In questo modo, una relazione diretta tra i fenomeni difrattura meso-strutturali ed il corrispondente danno macroscopico viene stabilita. Infine,uno studio numerico del comportamento macroscopico locale di danno idro-meccanico viene presentato
Nguyen, Trung Kien. „Homogénéisation numérique de structures périodiques par transformée de Fourier : matériaux composites et milieux poreux“. Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00598465.
Der volle Inhalt der QuelleCherblanc, Fabien. „Etude du tranport miscible en milieux poreux hétérogènes: Prise en compte du non-équilibre“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 1999. http://tel.archives-ouvertes.fr/tel-00010366.
Der volle Inhalt der QuelleCherblanc, Fabien. „Etude du transport miscible en milieux poreux hétérogènes : prise en compte du non-équilibre“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 1999. http://tel.archives-ouvertes.fr/tel-00106971.
Der volle Inhalt der Quelledans les sous-sols. La dispersion anormale observée à l'échelle de l'aquifère est en partie attribuée aux
effets du non-équilibre, comme l'échange de masse entre des régions présentant un contraste de
perméabilité élevé.
En présence de non-équilibre à grande échelle, le transport miscible ne peut plus être décrit par une
équation classique de convection-dispersion. Une méthode de changement d'échelle doit permettre de
prendre en compte les hétérogénéités, et donner une représentation macroscopique du transport.
Différentes techniques peuvent être utilisées, la méthode de prise de moyenne volumique à grande échelle
est employée ici. Cette méthode calcule les équations de transport et les propriétés effectives associées
par un processus de moyenne spatiale sur les équations correspondant à l'échelle inférieure. Au travers de
trois problèmes de fermeture, une expression explicite des propriétés à grande échelle est proposée. Le
modèle obtenu peut être vu comme une extension des modèles à double-porosité, capable de représenter
la plupart des comportements anormaux. Différents modèles à une équation sont ensuite dérivés et
comparés entre eux (comportement asymptotique, hypothèse d'équilibre local, cas de non-équilibre).
Une procédure numérique générale est mise en place afin de résoudre les problèmes de fermeture,
et ainsi calculer les coefficients de transport macroscopiques. Afin de valider le modèle à deux équations,
les prédictions théoriques sont comparées aux expériences numériques réalisées sur des milieux stratifiés
et nodulaires. Nous explorons enfin la possibilité d'utiliser une approche à deux équations en relation avec
une définition géo-statistique des hétérogénéités. Des systèmes stratifiés aléatoires et des milieux
aléatoires bi-dimensionnels sont étudiés, un bon accord est obtenu entre l'approche théorique et les
résultats expérimentaux.
Mesnier, Raphaël. „Étude des liens entre la texture et les propriétés de diffusion de molécules modèles dans des milieux poreux bimodaux“. Phd thesis, Toulouse, INPT, 2008. http://oatao.univ-toulouse.fr/7773/1/mesnier.pdf.
Der volle Inhalt der QuelleCoulaud, Olivier. „Contribution à l'étude des écoulements en milieux poreux : résolution des équations de Navier-Stokes par des méthodes spectrales et multigrilles“. Bordeaux 1, 1988. http://www.theses.fr/1988BOR10636.
Der volle Inhalt der QuelleMaisse, Éric. „Analyse et simulations numériques de phénomènes de diffusion-dissolution - précipitation en milieux poreux, appliquées au stockage de déchets“. Lyon 1, 1998. http://www.theses.fr/1998LYO10021.
Der volle Inhalt der QuelleVohralik, Martin. „Méthodes numériques pour des équations elliptiques et paraboliques non linéaires. Application à des problèmes d'écoulement en milieux poreux et fracturés“. Phd thesis, Université Paris Sud - Paris XI, 2004. http://tel.archives-ouvertes.fr/tel-00008451.
Der volle Inhalt der QuelleVohralík, Martin. „Méthodes numériques pour les équations elliptiques et paraboliques non linéaires : application à des problèmes d'écoulement en milieux poreux et fracturés“. Paris 11, 2004. https://tel.archives-ouvertes.fr/tel-00008451.
Der volle Inhalt der QuelleWe study numerical methods for the simulation of flow and contaminant transport in porous and fractured media. In Chapter 1 we propose a scheme allowing for efficient, robust, conservative, and stable discretizations of nonlinear degenerate parabolic convection–reaction–diffusion equations on unstructured grids in two or three space dimensions. We discretize the generally anisotropic diffusion term by means of the nonconforming finite element method and the other terms by means of the finite volume method and show the existence and uniqueness of a discrete solution and its convergence to a weak solution. We finally propose a version of this scheme for nonmatching grids and apply it to real simulations. In Chapter 2 we present a direct proof of the discrete Poincaré–Friedrichs inequalities and indicate optimal values of the constants in these inequalities. The results are important in the analysis of nonconforming numerical methods. In Chapter 3 we show that the lowest-order Raviart–Thomas mixed finite element method is equivalent to a particular multi-point finite volume scheme. This approach allows significant reduction of the computational time of the mixed finite element method without any loss of its high precision, which is confirmed by numerical experiments. Finally, in Chapter 4 we propose a version of the lowest-order Raviart–Thomas mixed finite element method for flow simulation in fracture networks that perturb rock massifs, prove that it is well posed, and study its relation to the nonconforming finite element method
Daadaa, Mouna. „Discrétisation spectrale et par éléments spectraux des équations de Darcy“. Paris 6, 2009. http://www.theses.fr/2009PA066397.
Der volle Inhalt der QuelleSboui, Amel. „Quelques méthodes numériques robustes pour l'écoulement et le transport en milieu poreux“. Phd thesis, Université Paris Dauphine - Paris IX, 2007. http://tel.archives-ouvertes.fr/tel-00284856.
Der volle Inhalt der QuelleEnfin une méthode numérique pour le calcul de transport de contaminants est proposée. Les techniques précédentes sont implémentées en 3-D et des résultats numériques sont présentés sur le benchmark 3-D champ lointain du GDR Momas et de l'Andra.
Wu, Li. „Contribution to the multi-physics study of porous media heated intermittently by RF energy in a coaxial cell“. Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/15667/1/WU_Li.pdf.
Der volle Inhalt der QuelleKadiri, Mostafa. „Shape οptimizatiοn and applicatiοns tο hydraulic structures : mathematical analysis and numerical apprοximatiοn“. Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC214/document.
Der volle Inhalt der QuelleWe are interested in the theoretical and numerical study of different flow models (shallow water system, multilayer, stationary and non stationary porous media) and their applications to the shape optimization of some hydraulic structures.We explore the well-posedness of the models and derive the adjoint equations related to each system.A penalty method is used to relax the incompressibility constraint for the velocity. We express the shape gradient of the cost function in terms of the velocity value as a state variable, the adjoint variables and the unit normal vector to the boundary of the domain.We propose a discrete finite element method to approximate the solution for the penalizedproblem and establish a priori estimates to prove the convergence of the approximate solution to the solution of the non perturbed problem. Error estimates for the velocity and the pressure are established.The optimization procedure is implemented using the continuous adjoint method and the finite element method
El, Amri Hassan. „Analyse numérique et résultats d'existence pour quelques modèles de problèmes physiques : vibrations d'une barre mince sous contraintes, écoulements quasi-newtoniens, écoulements en milieux poreux“. Lyon 1, 1990. http://www.theses.fr/1990LYO10006.
Der volle Inhalt der QuelleHutridurga, Ramaiah Harsha. „Homogénéisation et dispersion pour des écoulements complexes en milieu poreux et applications“. Phd thesis, Palaiseau, Ecole polytechnique, 2013. https://theses.hal.science/index.php?halsid=b5dg7470uitq63omogbminqdg3&view_this_doc=pastel-00866253&version=1.
Der volle Inhalt der QuelleOur work is a contribution to the understanding of transport of solutes in a porous medium. It has applications in groundwater contaminant transport, CO2 sequestration, underground storage of nuclear waste, oil reservoir simulations. We derive expressions for the effective Taylor dispersion taking into account convection, diffusion, heterogeneous geometry of the porous medium and reaction phenomena. Microscopic phenomena at the pore scale are upscaled to obtain effective behaviour at the observation scale. Method of two-scale convergence with drift from the theory of homogenization is employed as an upscaling technique. In the first part of our work, we consider reactions of mass exchange type, adsorption/desorption, at the fluid-solid interface of the porous medium. Starting with coupled convection-diffusion equations for bulk and surface concentrations of a single solute, coupled via adsorption isotherms, at a microscopic scale we derive effective equations at the macroscopic scale. We consider the microscopic system with highly oscillating coefficients in a strong convection regime i. E. , large Péclet regime. The presence of strong convection in the microscopic model leads to the induction of a large drift in the concentration profiles. Both linear and nonlinear adsorption isotherms are considered and the results are compared. In the second part of our work we generalize our results on single component flow to multicomponent flow in a linear setting. In the latter case, the effective parameters are obtained using Factorization principle and two-scale convergence with drift. The behaviour of effective parameters with respect to Péclet number and Damköhler number are numerically studied. Freefem++ is used to perform numerical tests in two dimensions