Rozprawy doktorskie na temat „Conditions aux limites approchées”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Conditions aux limites approchées”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
Vial, Grégory. "Analyse multi-échelle et conditions aux limites approchées pour un problème avec couche mince dans un domaine à coin". Rennes 1, 2003. https://tel.archives-ouvertes.fr/tel-00005153.
Pełny tekst źródłaVial, Grégory. "Analyse asymptotique multi-échelle et conditions aux limites approchées pour un problème de couche mince dans un domaine à coin". Phd thesis, Université Rennes 1, 2003. http://tel.archives-ouvertes.fr/tel-00005153.
Pełny tekst źródłaAuvray, Alexis. "Contributions à l'amélioration de la performance des conditions aux limites approchées pour des problèmes de couche mince en domaines non réguliers". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC018/document.
Pełny tekst źródłaTransmission problems with thin layer are delicate to approximate numerically, because of the necessity to build meshes on the scale of the thin layer. It is common to avoid these difficulties by using problems with approximate boundary conditions — also called impedance conditions. Whereas the approximation of transmission problems by impedance problems turns out to be successful in the case of smooth domains, the situation is less satisfactory in the presence of corners and edges. The goal of this thesis is to propose new impedance conditions, more efficient, to correct this lack of performance. For that purpose, the asymptotic expansions of the various models -problems are built and studied to locate exactly the origin of the loss, in connection with the singular profiles associated to corners and edges. New impedance conditions are built, of multi-scale Robin or Venctel types. At first studied in dimension 2, they are then generalized in certain situations in dimension 3. Simulations have been carried out to confirm the efficiency of the theoretical methods to some
Rosier, Carole. "Étude numérique des équations bi-dimensionnelles de Navier-Stokes avec conditions aux limites périodiques". Paris 11, 1989. http://www.theses.fr/1989PA112234.
Pełny tekst źródłaThe aim of this work is to describe a new numerical method, well suited for computing the solution of the Navier-Stokes equations over large time intervals. Introduced by Foias, Manley and Temam, this method corresponds to a projection of the equations on a nonlinear subspace, while the usual Galerkin method can be interpreted as a projection on a linear space; this is why it is called "The nonlinear Galerkin method". The work is organized as follows. In the first chapter a description of the problem is presented and some theoretical results concerning the behavior as it goes to infinity of the solutions are recalled. The second chapter is devoted to a comparative study of schemes based on different time discretizations of the Navier-Stokes equations. Our study shows that the predictor-corrector or Runge-Kutta schemes are better suited to the Galerkin approximation than a projection scheme or the Adams-Bashforth-Crank Nicholson scheme. These schemes are used in the numerical calculations. In the third chapter, a theoretical motivation of the nonlinear Galerkin method is presented. We define manifolds, the approximate inertial manifolds, which approximate the strange attractor, and which describe the interaction between the small and large eddies of the flow. Numerical tests are given in the last chapter
Chamaillard, Mathieu. "Effective boundary conditions for thin periodic coatings". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLY001.
Pełny tekst źródłaWe have dealt with the case of the scalar Helmholtz equation. We will try to handle the case of Maxwell's equation. We also will focus on the case of meta-materials. In a first case the permittivity is negative in the thin layer and in the second case is the permeability (1/delta) ^ 2
Abbaspour, Nima. "Approche numérique et expérimentale des écoulements au sein des piles à combustible : innovations liées aux conditions aux limites". Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0507.
Pełny tekst źródłaThis thesis is part of a wider project that aims at improving proton exchange membrane fuel cell (PEMFC) efficiency and stability. Our contribution aims at improving the geometry and structure of channels in anode and cathode bipolar plates (BPP) using experiments and simulations. The operation of a PEMFC involves multiphase flows and multiphysics phenomenon such as reactant concentration and electron exchange between the components. To simulate such a complex system employed industrial codes as well as Lattice Boltzmann Method. Chapter 1 reminds the basic principle of PEM fuel cell and the role of the fluids that flow through BPP channels. We describe a standard version of the latter and the modifications which we consider here. Chapter 2 details a classical model that describes PEM fuel cell operation in steady regime and assumes single phase flows in channels. The underlying equations and their simulation (using COMSOL) are validated by an experiment performed on standard single cell. The simulation evidences channels exhibiting unequal fluid fluxes while the literature points the negative effects of such heterogeneity. Since the used models disregards the possibility of having water in two phases, Chapter 3 describes a LBMcolorgradientcodefortwophaseflows. Wevalidateitagainstanexperimentperformed of a T-junction, a device that has applications beyond fuel cell. Chapter 4, differently, is devoted to steady gas flows in parallel channels that differ from standard fuel cell. An algorithm automatically homogenizes the fluid flow by modifying domain geometry within definite limits. It applies to diverse settings, and manages parallel channels by varying parameters as channel number and widths. However, the distributing channels that span the fluid between channels at BPP inlet and recollect it at outlet also matter. The author thus proposes designs that equalize channel flows. The author creates a new design to study the manufacturing feasibility of BPP. Chapter 5 describes water drop directional spreading on metallic structures decorated with fin shaped channels of parallel axis: experiments reveal almost total spreading only in one direction. Three dimensional LBM and Volume of Fluid simulationsretrievetheobservedtrendandcapturesmallerscaledetailssuggestingsubsetsof the fluid domain where capillary forces or inertia dominate. Most significant results are two phase flows simulations. They describe the different regimes of films or drops at the outlet of a T-junction whose other branches are fed with immiscible wetting and non-wetting fluids. Moreover, they describe how water drops spread on a microscopic relief which results into skewed capillary force
Ferrier, Renaud. "Stratégies de résolution numérique pour des problèmes d'identification de fissures et de conditions aux limites". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN034/document.
Pełny tekst źródłaThe goal of this thesis is to study and to develop some methods in order to solve two types of identification problems in the framework of elliptical equations. As those problems are known to be particularly unstable, the proposed methods are accompanied with regularization procedures, that ensure that the obtained solutions keep a physical meaning.Firstly, we study the resolution of the Cauchy problem (boundary conditions identification) by the Steklov-Poincaré method. We start by proposing some improvements based on the used Krylov solver, especially by introducing a regularization method that consists in truncating the Ritz values decomposition of the operator in question. We study afterwards the estimation of uncertainties by the mean of techniques stemming from Bayesian inversion. Finally, we aim at solving more demanding problems, namely a time-transient problem, a non-linear case, and we give some elements to carry out resolutions on geometries that have a very high number of degrees of freedom, with help of domain decomposition.As for the problem of crack identification by the reciprocity gap method, we firstly propose and numerically test some ways to stabilize the resolution (use of different test-functions, a posteriori minimization of the gradients or Tikhonov regularization). Then we present an other variant of the reciprocity gap method, that is applicable on cases for which the measurements are incomplete. This method, based on a Petrov-Galerkin approach, is confronted, among others, with an experimental case. Finally, we investigate some ideas that allow to extend the reciprocity gap method for the identification of non-plane cracks
ROUSSEL, FABIENNE. "Simulation numerique d'ecoulements de fluides compressibles visqueux par une approche fluide parfait avec conditions aux limites de paroi modelisant la couche limite". Paris 6, 1992. http://www.theses.fr/1992PA066316.
Pełny tekst źródłaPhan, Minh Tuyen. "Modélisation explicite de l'écaillage sous incendie du béton : approche thermo-hydro-mécanique avec des conditions aux limites évolutives". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00787946.
Pełny tekst źródłaPhan, Minh Tuyen. "Modélisation explicite de l’écaillage sous incendie du béton : approche thermo-hydro-mécanique avec des conditions aux limites évolutives". Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1155/document.
Pełny tekst źródłaIn the recent years, there were major tunnels fires which caused fatalities and severe traffic restrictions. In such extreme conditions (temperatures exceeding 1200 °C for considerable time spans), pore pressure build-up, restrained thermal dilatation, cement paste to aggregate incompatibility, dehydration... are some main degradation mechanisms of concrete that may cause its thermal spalling. Progressive concrete spalling occurring during a fire presents as the breakdown of surface layers which flake into small pebble-like pieces. Then, the resistant section of the structure reduces which may lead to its premature failure.In this thesis, a THM finite element model is enriched with a detachment-buckling type criterion for progressive spalling. The thermo-hygral part of the THM model is based on the three fluid approach for partially saturated porous media. The mechanical part is derived within the framework of thermo-poro-mechanics coupled to damage and softening plasticity.The adopted modeling of spalling leads to a problem with evolving boundary and boundary conditions. A suitable numerical solution strategy without remeshing is then developed in order to transfer properly the THM boundary conditions simultaneously with spalling occurrence.The efficiency of the model THM-Spalling is illustrated by some numerical examples and by parametric studies. These studies identify the influence, on spalling, of size variation of spalling flakes, the average spalling velocity and uncertainties on different material parameters. Confrontation with experimental tests shows satisfactory capacity of the THM-Spalling model in reproducing qualitatively the occurrence of spalling
Ben, Zitoun Feyed. "Une nouvelle méthode pour la résolution d'équations fonctionnelles non linéaires et résolution d'un problème issu de la microscopie électronique". Lorient, 2010. http://www.theses.fr/2010LORIS185.
Pełny tekst źródłaThis thesis is composed of two parts. In the first part, we present a new method allowing to resolve a wide variety of functional equations. This method reduce a nonlinear functional equation (in constant and\or variable coefficients and with or without initial conditions and in the limits) to a system of algebraic equations. The problem consisting in resolving a nonlinear functional equation is so simplified and returned to the resolution of a system of algebraic equations. The resolution of this system allows to obtain Solution of the nonlinear functional equation under the shape of a truncated series. Our method makes no discrétisation what allows to obtain a value approached the exact solution of the functional equation completely of the domain. Having exposed our method in a general frame, the resolution of some problems tests brings to light the simplicity of the effective implementation of our technique The flexibility and the efficiency of our method and the precision of our results. In the second part, we approach a problem stemming from the electronic microscopy. We show that we can find the speed of an image supplies by an electron microscope with sweeping and stemming from the interaction of an electron beam with the surface of a sample of composite material by an approach of modelling of the potential of surface and an estimate of the value of the potential of surface. We observe an analogy between the digital mapping of the potential of surface at differents points of the sample and the contrasted image obtained with the scanning electron microscope
Diaz, Julien. "Approches analytiques et numériques de problèmes de transmission en propagation d'ondes en régime transitoire : application au couplage fluide-structure et aux méthodes de couches parfaitement adaptées". Phd thesis, Paris 6, 2005. http://tel.archives-ouvertes.fr/tel-00008708.
Pełny tekst źródłaDelavaud, Virginie. "Modélisation temporelle de l'interaction roue/rail pour une application au bruit de roulement ferroviaire". Phd thesis, Palaiseau, Ecole polytechnique, 2011. http://pastel.archives-ouvertes.fr/pastel-00628346.
Pełny tekst źródłaBaydoun, Ramez. "Modélisation de l'écaillage sous incendie des bétons par une approche thermo-hydro-mécanique du comportement : Analyse paramétrique des différents mécanismes d'occurence". Thesis, Rennes, INSA, 2019. http://www.theses.fr/2019ISAR0012.
Pełny tekst źródłaSpalling of concrete under fire is an instability that consists of the expulsion of concrete material in the form of spalls from the surface exposed to fire. The analysis of the spalling phenomenon requires the understanding and the characterization of concretes at high temperature. ln this thesis, a THM finite element model is developed to simulate the high temperature behavior, especially under fast-burning tire, of different types of concrete (from ordinary concrete to ultra-high performance). The Thermo-Hygral part of the THM model is based on the three-fluid approach in partially saturated media. To ensure numerical model stability in case of rapid development fire, we have appropriately chosen the TH state variables to control the solution of the finite element model. The mechanical model used is a modified Mazars model adapted to high temperature. This THM model is enriched by a progressive spalling model by proposing different detachment-buckling or confined bending expulsion type. This modeling of spalling leads to a problem with evolving boundary and boundary conditions. A strategy without remeshing was developed to transfer properly the THM boundary conditions simultaneously with spalling occurrence. The model is implemented in the CAST3M finite element code. A comparative analysis of different criteria explaining the occurrence of flaking is conducted to evaluate their relevance and ability to describe the phenomenon and to reconstruct the experimental observations for different classes of concrete and type of fire
Gauthier, Bertrand. "Approche spectrale pour l'interpolation à noyaux et positivité conditionnelle". Phd thesis, École Nationale Supérieure des Mines de Saint-Étienne, 2011. http://tel.archives-ouvertes.fr/tel-00631252.
Pełny tekst źródłaGonzalez, Thierry. "Contributions aux conditions d'interface et conditions aux limites pour le systeme d'equations euler compressible". Paris 6, 2000. http://www.theses.fr/2000PA066512.
Pełny tekst źródłaBrouillat, Sébastien. "Conditions aux limites absorbantes d'ordre élevé en électromagnétisme". Bordeaux 1, 1996. http://www.theses.fr/1996BOR10608.
Pełny tekst źródłaEl, Ouaraini Rachida. "Sensibilité des assimilations d'ensemble globales et régionales aux conditions initialites et aux conditions limites latérales". Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/15999/1/ElOuaraini.pdf.
Pełny tekst źródłaUzan, Jean-Philippe. "Defauts topologiques et conditions aux limites en cosmologie primordiale". Paris 11, 1998. http://www.theses.fr/1998PA112143.
Pełny tekst źródłaSesques, Muriel. "Conditions aux limites artificielles pour le système de Maxwell". Bordeaux 1, 1990. http://www.theses.fr/1990BOR10606.
Pełny tekst źródłaBergeret, Pascale. "Systèmes de lois de conservation, effets non linéaires des conditions aux limites : traitement numérique des conditions aux limites et des jonctions dans un réseau de pipelines". Lyon 1, 1995. http://www.theses.fr/1995LYO10004.
Pełny tekst źródłaMachrouki, Hicham. "Incompressibilité et conditions aux limites dans la méthode Smoothed particle hydrodynamics". Poitiers, 2012. http://theses.univ-poitiers.fr/25282/2012-Machrouki-Hicham-These.pdf.
Pełny tekst źródłaA numerical particle method for solving the Bavier-Stokes equations in velocity-pressure formulation for two dimensional incompressible flows is presented. The basis of the method is the Smoothed particle hydrodynamics (SPH) formulation for the moment transport. On advantage of this meshless method is an easy treatment of computational domains with complex boundaries. The pressure is computed by solving a poisson equation that ensures the flow incompressibility and the boundary conditions are imposed by using a boundary integral method (BIM). This last method, is known to be strongly CPU time consuming. To overcome this difficulty, the source term of the poisson equation was solved by introducing a cartesian grid and by using finite differences. The same treatment has been applied to the generalize Helmholtz equation for the velocity field as well. The different steps were validated by studying several academic cases including a driven cavity low, a dam break and an impulsively started flow around a circular cylinder. Aditionaly to this standard use for flow numerical modelling, the method was also applied for rebuilding the pressure and velocity fields from velocity fields experimentally measured by a PIV method. The method was then applied to the flow around a moving NACA profile
TAJCHMAN, MARC. "Conditions aux limites absorbantes pour des fluides viscoélastiques de type différentiel". Paris 11, 1994. http://www.theses.fr/1994PA112100.
Pełny tekst źródłaBarucq, Hélène. "Etude asymptotique du système de Maxwell avec conditions aux limites absorbantes". Bordeaux 1, 1993. http://www.theses.fr/1993BOR10620.
Pełny tekst źródłaCroizet, Cédric. "Modelisation cinetique d'une suspension et conditions aux limites sur une paroi". Paris 6, 2000. http://www.theses.fr/2000PA066499.
Pełny tekst źródłaGauthier, Bertrand. "Approche spectrale pour l’interpolation à noyaux et positivité conditionnelle". Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0615/document.
Pełny tekst źródłaWe propose a spectral approach for the resolution of kernel-based interpolation problems of which numerical solution can not be directly computed. Such a situation occurs in particular when the number of data is infinite. We first consider optimal interpolation in Hilbert subspaces. For a given problem, an integral operator is defined from the underlying kernel and a parameterization of the data set based on a measurable space. The spectral decomposition of the operator is used in order to obtain a representation formula for the optimal interpolator and spectral truncation allows its approximation. The choice of the measure on the parameters space introduces a hierarchy onto the data set which allows a tunable precision of the approximation. As an example, we show how this methodology can be used in order to enforce boundary conditions in kernel-based interpolation models. The Gaussian processes conditioning problem is also studied in this context. The last part of this thesis is devoted to the notion of conditionally positive kernels. We propose a general definition of symmetric conditionally positive kernels relative to a given space and exposed the associated theory of semi-Hilbert subspaces. We finally study the optimal interpolation problem in such spaces
Prat, Marc. "Modélisation des transferts en milieux poreux : changement d'échelle et conditions aux limites". Toulouse, INPT, 1989. http://www.theses.fr/1989INPT067H.
Pełny tekst źródłaLohéac, Jean-Pierre. "Conditions aux limites artificielles pour des modèles de la mécanique des fluides". Lyon 1, 1989. http://www.theses.fr/1989LYO19009.
Pełny tekst źródłaDarblade, Gilles. "Méthodes numériques et conditions aux limites pour les modèles Shallow-Water multicouches". Bordeaux 1, 1997. http://www.theses.fr/1997BOR10588.
Pełny tekst źródłaChalindar, Bruno. "Conditions aux limites absorbantes appliquées à des problèmes hyperboliques intervenant en sismique". Saint-Etienne, 1988. http://www.theses.fr/1988STET4013.
Pełny tekst źródłaHouari, Menouar. "Etude des conditions aux limites dans un modèle numérique d'agitation de houle". Marne-la-vallée, ENPC, 2002. http://www.theses.fr/2002ENPC0209.
Pełny tekst źródłaCORNUBERT, REMI. "Conditions aux limites des modeles cinetiques discrets : couche de knudsen et obstacles". Paris 6, 1991. http://www.theses.fr/1991PA066450.
Pełny tekst źródłaChalindar, Bruno. "Conditions aux limites absorbantes appliquées à des problèmes hyperboliques intervenant en sismique". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37612449h.
Pełny tekst źródłaKarimou, Gazibo Mohamed. "Etudes mathématiques et numériques des problèmes paraboliques avec des conditions aux limites". Phd thesis, Université de Franche-Comté, 2013. http://tel.archives-ouvertes.fr/tel-00950759.
Pełny tekst źródłaTourrette, Loïc. "Conditions aux limites artificielles pour les équations de Navier-stokes compressibles linéarisées". Palaiseau, Ecole polytechnique, 1990. http://www.theses.fr/1990EPXX0006.
Pełny tekst źródłaEl, Hamdani Driss. "Application de la théorie de l'homogénéisation aux problèmes aux limites : À conditions périodiques, en formulation intégrale". Besançon, 1990. http://www.theses.fr/1990BESA2005.
Pełny tekst źródłaFavraud, Gael. "Acoustique dans les écoulements cisaillés : conditions limites de géométries complexes, application à l’acoustique et aux couches limites visqueuses". Thesis, Le Mans, 2012. http://www.theses.fr/2012LEMA1024/document.
Pełny tekst źródłaThe first part is a study of the interactions between acoustic and vorticity perturbations in linear incompressible shear flows, which can decomposed as a sum of a hyperbolic part and of a rigid rotation part. The plane Couette flow is an example of such flows. By using the non-modal approach, the equations governing the evolution of compressible perturbations reduce to an ODE of dimension three in time, which depends on a dimensionless parameter ε representing the ratio between the shear rate of the flow and the frequency of the perturbations. For small ε values, the WKB method allows us to exhibit naturally three modes (two acoustic modes and one vorticity mode) and to highlight couplings between these modes. These couplings are exponentially small in 1/ε, and cannot be taken into account by an asymptotic method. They seem to be linked to the hyperbolic part of the flow.The second part deals with the reflection of a wave by a geometrically complex surface. A conformal mapping allows us to transform a complex boundary into a plane boundary, but makes appear varying coefficients in the bulk equations. These equations are then solved with the multimodal impedance matrix method, which reduce the problem to a Riccati equation for the impedance matrix. A method to find geometries allowing for the existence of trapped modes is proposed. Then the solving method is applied to the modeling of the viscous boundary layer of a fluid oscillating near a periodical rough surface. A perturbative solution is proposed. The presence of recirculation areas is studied
Favraud, Gael. "Acoustique dans les écoulements cisaillés : conditions limites de géométries complexes, application à l'acoustique et aux couches limites visqueuses". Phd thesis, Université du Maine, 2012. http://tel.archives-ouvertes.fr/tel-00821059.
Pełny tekst źródłaLamarque, Nicolas Poinsot Thierry. "Schémas numériques et conditions limites pour la simulation aux grandes échelles de la combustion diphasique dans les foyers d'hélicoptère". Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000593.
Pełny tekst źródłaDuprat, Véronique. "Conditions aux limites absorbantes enrichies pour l'équation des ondes acoustiques et l'équation d'Helmholtz". Phd thesis, Université de Pau et des Pays de l'Adour, 2011. http://tel.archives-ouvertes.fr/tel-00817506.
Pełny tekst źródłaMeslameni, Mohamed. "Équations de Stokes et d'Oseen en domaine extérieur avec diverses conditions aux limites". Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3002/document.
Pełny tekst źródłaIn this work, we study the linearized Navier-Stokes equations in an exterior domain or in the whole space at the steady state, that is, the Stokes equations and the Oseen equations. We give existence, uniqueness and regularity of solutions. The case of very weak solutions is also treated. We consider not only the Dirichlet boundary conditions but also the Non Standard boundary conditions, on some components of the velocity field, vorticity and also on the pressure. Since the domain is not bounded, the classical Sobolev spaces are not adequate. Therefore, a specific functional framework is necessary which also has to take into account the behaviour of the functions at infinity. Our approach rests on the use of weighted Sobolev spaces
Gisclon, Marguerite. "Etude des conditions aux limites pour des systèmes strictement hyperboliques, via l'approximation parabolique". Lyon 1, 1994. http://www.theses.fr/1994LYO10294.
Pełny tekst źródłaVovelle, Julien. "Prise en compte des conditions aux limites dans les équations hyperboliques non-linéaires". Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX11059.
Pełny tekst źródłaMondoloni, Antoine. "Existence d'une solution faible d'une équation d'onde quasi-linéaire avec conditions aux limites". Corte, 2000. http://www.theses.fr/2000CORT3052.
Pełny tekst źródłaKadri, Harouna Souleymane. "Ondelettes pour la prise en compte de conditions aux limites en turbulence incompressible". Grenoble, 2010. http://www.theses.fr/2010GRENM050.
Pełny tekst źródłaThis work concerns wavelet numerical methods for the simulation of incompressible turbulent flow. The main objective of this work is to take into account physical boundary conditions in the resolution of Navier-Stokes equations on wavelet basis. Unlike previous work where the vorticity field was decomposed in term of classical wavelet bases, the point of view adopted here is to compute the velocity field of the flow in its divergence-free wavelet series. We are then in the context of velocity-pressure formulation of the incompressible Navier-Stokes equations, for which the boundary conditions are written explicitly on the velocity field, which differs from the velocity-vorticity formulation. The principle of the method implemented is to incorporate directly the boundary conditions on the wavelet basis. This work extends the work of the thesis of E. Deriaz realized in the periodic case. The first part of this work highlights the definition and the construction of new divergence-free and curl-free wavelet bases on [0,1]n, which can take into account boundary conditions, from original works of P. G. Lemarie-Rieusset, K. Urban, E. Deriaz and V. Perrier. In the second part, efficient numerical methods using these new wavelets are proposed to solve various classical problem: heat equation, Stokes problem and Helmholtz-Hodge decomposition in the non-periodic case. The existence of fast algorithms makes the associated methods more competitive. The last part is devoted to the definition of two new numerical schemes for the resolution of the incompressible Navier-Stokes equations into wavelets, using the above ingredients. Numerical experiments conducted for the simulation of driven cavity flow in two dimensions or the issue of reconnection of vortex tubes in three dimensions show the strong potential of the developed algorithms
Tonnoir, Antoine. "Conditions transparentes pour la diffraction d'ondes en milieu élastique anisotrope". Palaiseau, École nationale supérieure de techniques avancées, 2015. http://www.theses.fr/2015ESTA0016.
Pełny tekst źródłaThis thesis is motivated by the numerical simulation of Non Destructive Testing by ultrasonic waves. It aims at designing a method to compute by Finite Element (EF) the diffraction of elastic waves in time-harmonic regime by a bounded defect in an anisotropic plate. The goal is to take into account an infinite plate and to restrict the FE calculations to a bounded area. This point is difficult due to the anisotropy and, in particular, methods such as perfectly matched layers fail. In this thesis, we have mainly considered two-dimensional cases that enabled us to implement the main ingredients of a method designed for the three-dimensional case of the plate. The first part deals with the diffraction problem in an infinite strip. The classical approach consists in writing transparent conditions by matching on a boundary the displacement and the axial stress using a modal expansion in the safe part of the plate, and the FE representation in the perturbed area. We have shown the interest of imposing these matching conditions on two separated boundaries, by introducing an overlap between the modal domain and the FE domain. Thus, we can take advantage of the bi-orthogonality relations valid for general anisotropy, and also improve the rate of convergence of iterative methods of resolution. In the second part, that represents the main part of the thesis, we discuss the diffraction problem in an anisotropic medium infinite in the two directions. The key idea is that we can express the solution (via the Fourier transform) in a half-plane given its trace on the boundary. Therefore, the approach consists in coupling several analytical representations of the solution in half-planes surrounding the defect (at least 3) with the FE representation. The difficulty is to ensure that all these representations match, in particular in the infinite intersections of the half-planes. It leads to a formulation which couples, via integral operators, the solution in a bounded domain including the defect, and its traces on the edge of the half-planes. The approximation releases a truncation and a discretization both in space and Fourier variables. For each of these two parts, the methods have been implemented and validated with a C++ code developed during the thesis, first in the scalar acoustic case, and then in the elastic case
Vezinet, René. "Conditions aux limites absorbantes d'ordre élevé appliquées aux équations de Maxwell dans le vide et en milieu conducteur". Limoges, 1993. http://www.theses.fr/1993LIMO0225.
Pełny tekst źródłaRejaiba, Ahmed. "Equations de Stokes et de Navier-Stokes avec des conditions aux limites de Navier". Thesis, Pau, 2014. http://www.theses.fr/2014PAUU3050/document.
Pełny tekst źródłaThis thesis is devoted to the study of the Stokes equations and Navier-Stokes equations with Navier boundary conditions in a bounded domain of . The work contains three chapters: In the first chapter, we consider the stationary Stokes equations with Navier boundary condition. We show the existence, uniqueness and regularity of the solution in the Hilbert case and in the -theory. We prove also the case of very weak solutions. In the second chapter, we focus on the Navier-Stokes equations with the Navier boundary condition. We show the existence of the weak solution in , with by a fixed point theorem over the Oseen equation. We show also the existence of the strong solution in . In chapter three, we study the evolution Stokes problem with Navier boundary condition. For this, we apply the analytic semi-groups theory, which plays a crucial role in the study of existence and uniqueness of solution in the case of the homogeneous evolution problem. We treat the case of non-homogeneous problem through imaginary powers of the Stokes operator
Pilon, Dominic. "Influence des conditions aux limites sur les mesures acoustiques au tube à ondes stationnaires". Mémoire, Université de Sherbrooke, 2002. http://savoirs.usherbrooke.ca/handle/11143/1172.
Pełny tekst źródłaOuarzazi, Mohamed-Najib. "Bifurcations associées à des imperfections des conditions aux limites pour des problèmes de convection". Lille 1, 1993. http://www.theses.fr/1993LIL10147.
Pełny tekst źródła