[Truncated abstract] To date, many subsurface contaminant modelling studies have focused on increasing model complexity and measurement requirements to improve model accuracy and widen model application. However, due to the highly complex and heterogeneous nature of flow in the subsurface, the greater benefit in model development may lie in decreasing complexity by identifying key processes and parameters, simplifying the relationships that exist between them, and incorporating these relationships into simple models that recognise or quantify the inherent complexity and uncertainty. To address this need, this study aims to identify and isolate the key processes and parameters that control dense nonaqueous phase liquid (DNAPL) and aqueous phase migration through single, onedimensional fractures. This is a theoretical representation which allows the study of processes through conceptual and mathematical models. Fracture systems typically consist of multiple two-dimensional fractures in a three-dimensional network; however, these systems are computationally and conceptually demanding to investigate and were outside of the scope of this study. This work initially focuses on DNAPL migration in single, one-dimensional fractures. The similitude techniques of dimensional and inspectional analysis are performed to simplify the system and to develop breakthrough time scale factors. This approach relies heavily on the limitations of the equation used for the analysis and on the difficulty in representing variable aperture scenarios. The complexity of the conceptual model is then increased by embedding the fracture in a two-dimensional, porous matrix. ... These tools can be readily applied by the field investigator or computer modeller to make order-of-magnitude estimates of breakthrough times, reduce or target measurement requirements, and lessen the need to employ numerical multiphase flow models. To determine the implications of the results found in the one-dimensional studies to applications at the field scale, the complexity of the conceptual model was increased to a single, two-dimensional, planar fracture embedded in a three-dimensional porous matrix. The focus of this study was not DNAPL breakthrough times but the relative importance and interaction of different mass transport processes and parameters on plume migration and evolution. Observations clearly show that estimates of the size, location and concentration of the plume is highly dependent on the geologic media, the temporal and spatial location and resolution of measurements, and on the history, mass and location of the DNAPL source. In addition, the processes controlling mass transport (especially matrix diffusion and back diffusion) act in combination at the field scale in ways not always expected from an analysis of processes acting individually at smaller spatial and temporal scales. Serious concerns over the application of the common '1% Rule of Thumb' to predict DNAPL presence and the use of remediation efforts that rely largely on natural attenuation are raised. These findings have major implications for the field worker and computer modeller, and any characterisation, monitoring or remediation program development needs to be sensitive to these findings.

Made available in DSpace on 2014-12-17T14:48:17Z (GMT). No. of bitstreams: 1 GilvanBSJ_DISSERT.pdf: 3763149 bytes, checksum: 74cfc52e8eaadf3e1722a2a37d52aca9 (MD5) Previous issue date: 2014-03-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Usually masonry structures has low tension strength, hence the design to flexural efforts can results in high reinforcement ratio, specification of high unit and prism strength, structural members with larger section dimensions and modification in structural arrangement to be possible to use masonry members. The main objective of this study is to evaluate the stiffness, the efforts distribution and the effect of horizontal elements (girders) and vertical elements (counterforts) distribution on the behavior of masonry blocks retaining walls. For this purpose, numerical modeling was performed on typical retaining wall arrangements by varying the amount and placement of horizontal and vertical elements, beyond includes elements simulating the reactions of the soil supporting the foundation of the wall. The numerical modeling also include the macro modeling strategy in which the units, mortar and grout are discretized by a standard volume that represents the masonry elastic behavior. Also, numerical model results were compared with those ones of simplified models usually adopted in bending design of masonry elements. The results show horizontal displacements, principal and shear stresses distribution, and bending moments diagrams. From the analysis it was concluded that quantity and manner of distribution of the girders are both important factors to the panel flexural behavior, the inclusion of the foundation changed significantly the behavior of the wall, especially the horizontal displacements, and has been proposed a new way of considering the flanges section of the counterforts / As estruturas de alvenaria solicitadas por elevados esfor?os de flex?o podem necessitar, dada a baixa resist?ncia ? tra??o, de elevadas taxas de armadura; de maior resist?ncia ? compress?o da alvenaria; de elementos estruturais com maiores dimens?es ou mesmo um rearranjo desses elementos para possibilitar o emprego da alvenaria. O estudo ora apresentado tem por objetivo avaliar a rigidez, a distribui??o de esfor?os e o efeito da distribui??o de cintas e de elementos verticais (contrafortes) no caso de muros de arrimo de alvenaria estrutural de blocos. Para tanto, foram realizadas modelagens num?ricas de arranjos t?picos de muro, variando a quantidade e o posicionamento de cintas horizontais, o espa?amento entre os contrafortes, al?m de incluir elementos simulando as rea??es do solo de apoio na funda??o do muro. A modelagem num?rica realizada empregou a estrat?gia de macromodelagem em que os blocos, a argamassa e o graute s?o discretizados pelo volume padr?o representativo do comportamento el?stico da alvenaria. Alternativamente, os resultados do modelo num?rico foram comparados com os de modelos simplificados comumente adotados nos projetos desse tipo de elemento estrutural. A an?lise dos resultados consistiu na verifica??o dos deslocamentos transversais, na distribui??o das tens?es principais (para balizar um futuro modelo de bielas e tirantes e os modos de ruptura), na distribui??o das tens?es de cisalhamento, e na obten??o de diagramas de momento fletor. A partir das an?lises foi poss?vel concluir que n?o apenas a quantidade, mas tamb?m a forma de distribui??o das cintas ? um fator relevante para a distribui??o dos esfor?os no painel fletido (pano de alvenaria), a inclus?o dos elementos de funda??o alterou significativamente o comportamento do muro, principalmente os deslocamentos transversais, al?m de ter sido proposta uma nova forma de considera??o de flanges na se??o resistente do contraforte

[pt] Esta pesquisa investiga o comportamento sísmico da barragem de terra de Breapampa, situada no Peru em zona de atividade sísmica. A previsão numérica é feita com auxílio do programa computacional FLAC 2D v.7, baseado no método das diferenças finitas. É simulada a construção incremental da barragem, a elevação gradual do nível d água do reservatório durante a etapa do primeiro enchimento do reservatório, é estabelecida a posição da linha freática em regime de fluxo permanente e são calculados os fatores de segurança estático da estabilidade dos taludes nas condições de final da construção e após o primeiro enchimento do reservatório. A simulação do comportamento sísmico da barragem é feita em seguida, discutindo-se vários e importantes aspectos que devem ser considerados para uma correta análise como a seleção do terremoto de projeto, a filtragem de altas frequências para minimizar o número de elementos da malha, a introdução de condições de contorno silenciosas, a escolha de modelos constitutivos incluindo a incorporação de amortecimento histerético, entre outros pontos. A resposta sísmica da barragem, nas condições de reservatório vazio e reservatório cheio, foi obtida em termos de deslocamentos permanentes, história de deslocamentos, amplificações da aceleração horizontal, desenvolvimento de poropressões no corpo da barragem e potencial de ruptura cíclica no material do núcleo. / [en] This research investigates the seismic behavior of the Breapampa earth dam, situated in Peru within a seismic activity zone. The numerical prediction is carried out using the computer program FLAC 2D v.7, based on the finite difference method. it is simulated the incremental construction of the dam, the gradual raise of the water level during the stage of reservoir impounding, the establishment of the phreatic line under steady state flow and the determination of safety factor for the stability of the soil slopes considering both conditions of after construction and after reservoir impounding. The modeling of the seismic behavior of the dam is then made with detailed discussion of several important aspects for a correct analysis such as the selection of the design earthquake, the filtering of high frequencies in order to minimize the number of elements in the mesh, the introduction of silent boundaries, the choice of proper constitutive soil models including the representation of hysteretic damping, among others points. The seismic response of the dam, under the conditions of full and empty reservoir, was obtained in terms of permanent displacements, displacement history, amplifications horizontal acceleration amplification, porepressure distribution and potential of cyclic failure in the saturated material of the core of the dam.

Afin de surmonter les difficultés de la méthode des éléments finis (MEF) liées à la forte dépendance de la solution au maillage, des méthodes sans maillage ont été développées durant les 20 dernières années. Ces techniques ont l’avantage de procurer des approximations très régulières, capables de répondre de manière plus satisfaisante aux exigences croissantes des applications. Cependant, certaines caractéristiques intrinsèques à la plupart de ces approches rendent leur mise en œuvre difficile : souvent des techniques supplémentaires spécifiques doivent être mises en place pour imposer les conditions aux limites et traiter les discontinuités physiques. Récemment, la méthode des éléments naturels (MEN) est apparue, se basant sur les concepts de diagramme de Voronoï et de voisins naturels. C’est une approche capable d’associer les avantages d’une approximation très régulière propre aux méthodes sans maillage et une mise en œuvre quasiment identique à la MEF. Cette thèse porte sur l’étude et le développement de la MEN dédiée aux applications du génie électrique. Le but principal de ce travail exploratoire est l’étude des limitations ainsi que des avantages et du potentiel de la MEN et ses concepts sous-jacents. Les analyses de performances de la méthode sont présentées. Sur les points ouverts tels que l’intégration numérique, la montée en ordre et l’interpolation vectorielle, des développements originaux sont proposés. / In order to overcome the limitations related to the finite element method’s (FEM) narrow dependency of the solution on the mesh, meshless or meshfree methods were developed over the last 20 years. These techniques present the advantage of yielding very smooth approximations, being able to respond more adequately to the increasing demands of applications. However, some intrinsic features of most of these approaches make the implementation difficult, often requiring additional specific techniques for the imposition of the boundary conditions and the treatment of physical discontinuities. Recently, the natural element method (NEM) was developed. This approach, based on the Voronoi diagram and the “natural neighbors” concepts, combines the advantages of very smooth approximations and a FEM-like implementation. This thesis focuses on the study and development of the NEM, dedicated to electrical engineering applications. The main purpose of this exploratory work is the study of the limitations, benefits and the potential of the NEM and its underlying concepts. Several analyses of NEM’s performance are presented. As far as the numerical integration, higher order approximations and the vector interpolation are concerned, original developments are proposed.

En l’espace d’une quarantaine d’année, les connaissances sur l’angiogenèse tumorale ont littéralement explosé. Dans les années 1970, Judah Folkman démontre que les tumeurs ont besoin d’être vascularisées pour continuer à proliférer. Peu de temps après, les protagonistes principaux de l’angiogenèse tumorale ont été découverts, de même que les mécanismes dans lesquels ils sont impliqués. La décennie suivante marque le début des recherches sur les molécules à visée anti-angiogénique et c’est en 2004 que le bevacizumab (Avastin, Roche), premier médicament anti-angiogénique utilisé en oncologie, voit le jour. Parallèlement à cela, l’essor de la modélisation à effets-mixtes couplée aux progrès des outils informatiques ont permis de développer des méthodes d’analyses de données de plus en plus performantes. Dès 2009 L’agence de régulation FDA (Food and Drug Administration) aux Etats-Unis a identifié le rôle central de la modélisation numérique pour mieux analyser les données d’efficacité et de toxicité, préclinique et clinique en cancérologie. Le but de ce projet est d’étudier les effets de différents inhibiteurs de l’angiogenèse sur la dynamique tumorale, en se basant sur une approche populationnelle. Les modèles développés seront des modèles à base d’équations différentielles ordinaires intègrant des données et des informations issues de la littérature. L’objectif de ces modèles est de caractériser la dynamique des tailles tumorales chez les animaux et chez les patients, afin de comprendre les effets des traitements anti-angiogéniques et apporter un soutien pour le développement de ces molécules ou pour la prise de décisions thérapeutiques par les cliniciens. / Within the last 40 years, knowledge of tumor angiogenesis has literally exploded. In the seventies, Judah Folkman demonstrated that tumors need to be vascularized to continue to proliferate. Shortly after, the main protagonists of tumor angiogenesis have been discovered, as well as the mechanisms in which they are involved. The next decade is the beginning of the research on molecules with anti-angiogenic effects and in 2004 bevacizumab (Avastin, Roche), the first antiangiogenic drug used in oncology, was available for treating solid cancer patients. Along with this, the increasing interest of mixed-effects modeling coupled with advances in computer tools allowed developing more efficient methods of data analysis. In 2009, the regulatory agency FDA (Food and Drug Administration) in the United States has identified the central role of numerical modeling to better analyze the efficacy and toxicity preclinical and clinical oncology data. The aim of this project is to study the effects of different angiogenesis inhibitors on tumor dynamics, based on a population approach. The developed models are models based on ordinary differential equations and that integrate data and information from the literature. The objective of these models is to characterize the dynamics of tumor sizes in animals and patients in order to understand the effects of anti-angiogenic treatments and provide support for the development of these molecules, or to help clinicians for therapeutic decision making.

Le phénomène de coup de terrain est une explosion violente de roche qui peut se produire dans les mines souterraines. Dans la présente recherche, nous avons essayé de démontrer les causes qui peuvent influer sur la prédisposition aux coups de terrain en utilisant la modélisation numérique. Cependant, avant tout, l'état de contrainte avant l'exploitation minière et les contraintes induites par les excavations environnantes doivent être étudiés avec précision. La mine de charbon de Provence, qui a subi un phénomène de coup de terrain au niveau de son puits vertical entouré de nombreux panneaux de longue taille, a été choisie comme cas d’étude. Un modèle numérique 3D à grande échelle a été construit pour inclure la zone du puits vertical avec ses piliers et galeries à petite échelle et les panneaux de longue taille à grande échelle avec leurs zones de foudroyage associées. Plusieurs problèmes ont été rencontrés lors du développement de ce modèle numérique à grande échelle. Le premier porte sur l'initialisation de l'état de contrainte à grande échelle, où les contraintes verticales mesurées divergent avec le poids des déblais et les contraintes in situ sont très anisotropes. Le deuxième porte sur la simulation de la zone de foudroyage associée aux panneaux de longue taille. Le troisième concerne l'évaluation de l’instabilité du pilier en fonction de son ratio résistance/contrainte moyenne et de son volume. Le quatrième concerne l'évaluation de la prédisposition aux coups de terrain au niveau du puits vertical en fonction de différents critères. Cinq méthodes ont été développées pour initialiser l’état de contrainte hétérogène dans le modèle numérique à grande échelle avant l’exploitation minière. Elles sont basées sur la méthode de corrélation Simplex, qui consiste à optimiser la différence entre les valeurs de contrainte mesurées in-situ et les valeurs numériques. Le but est de développer des gradients qui soient capables d'exprimer l'hétérogénéité de la contrainte et qui soient compatibles avec les mesures in-situ. La méthode basée sur l’initialisation de l'état de contrainte avec des gradients 3D s’est avérée plus efficace que celle traditionnelle basée sur les ratios de contrainte horizontale à verticale. Concernant la simulation du foudroyage, trois modèles ont été développés et intégrés dans le modèle numérique pour exprimer le comportement mécanique dans la zone de foudroyage au-dessus des panneaux de longue taille. Deux d’entre eux sont basés sur un comportement élastique alors que le troisième est basé sur un comportement elasto-plastique avec écrouissage un phénomène de consolidation. Il a été constaté que la zone de foudroyage au-dessus des panneaux de longue taille peut atteindre 32 fois l'épaisseur de la couche exploitée et que le module d'élasticité de la partie la plus endommagée de la zone foudroyée ne doit pas excéder 220 MPa pour satisfaire la convergence toit-mur. Mais, avec l'avancée de l'exploitation, ce matériau souple se compacte sous la pression des couches supérieures. Dans le cas d'une largeur critique et super-critique, la contrainte verticale dans la zone de foudroyage pourrait dépasser le poids des déblais et pourrait augmenter jusqu'à 4 fois ce poids sur les bords. La contrainte verticale a augmenté dans les piliers au niveau du puit vertical suite à l'exploitation des panneaux de longue taille à proximité. Il a été constaté que le volume du pilier joue un rôle important dans sa stabilité. Le rapport contrainte/résistance a été jugé insuffisant pour expliquer un coup de terrain. Plusieurs critères ont été intégrés au modèle numérique pour évaluer la prédisposition aux coups de terrain. Il a été constaté que les critères basés sur les contraintes et les déformations sont capables d'évaluer la prédisposition aux coups de terrain / Rockburst is a violent explosion of rock that can occur in underground mines. In the current research, the main objective is to demonstrate the causes that may influence the rockburst proneness by using the numerical modeling tool. However, firstly, the pre-mining stress state and the induced stresses due to surrounding excavations have to be studied precisely. The Provence coal mine, where a rockburst took place in its shaft station that is surrounded by many longwall caving panels, has been chosen as a case study. A large-scale 3D numerical model has been constructed to include the shaft station area with its small-scale pillars and galleries, and the large-scale longwall panels with their accompanying goaf area. Many problems appeared while developing such large-scale numerical model, the first problem was the initialization of stress state at a large-scale, where the measured vertical stresses are in disagreement with the overburden weight, and the in-situ stresses are highly anisotropic. The second problem was the simulation of the goaf area accompanying longwall panels. The third problem was the assessment of pillars instability in terms of its strength/average stress ratio, and its volume. The Fourth problem was the assessment of rockburst proneness in the shaft station based on different rockburst criteria. Five methods were developed to initialize the heterogeneous pre-mining stress in the large-scale numerical model. These methods are based on the Simplex Method, which is mainly based on optimizing the difference between the in-situ measured stress values and the numerical stress values to develop stress gradients able to express the stress heterogeneity and compatible with the in-situ measurements. The method that is based on initiating the stress state with 3D stress gradients was found to be more efficient than the traditional method that is based on the horizontal-to-vertical stress ratios. Regarding the goaf simulation, three models were developed and implemented in the numerical model to express the mechanical behavior within the goaf area above longwall panels. Two of these models are based on an elastic behavior, and the third one is based on the strain-hardening elasto-plastic behavior that takes the consolidation phenomenon into consideration. It was found that the goaf area above longwall panels could reach up to 32 times the seam thickness, and the elastic modulus of caved area (the first few meters in the goaf area) did not exceed 220 MPa to fulfill the roof-floor convergence. But, with advance of the exploitation, this soft material consolidated under the pressure of the overlying strata. In case of critical and super-critical width, the vertical stress in the goaf area exceeded the overburden weight, and it increased up to 4 times the overburden weight on the rib-sides. The vertical stress increased in the shaft station pillars as a result of exploiting the nearby longwall panels. It was found that the pillar volume plays an important role in its stability. And, the strength/stress ratio was found to be insufficient to quantify the rockburst proneness in underground mines. Many rockburst criteria were implemented in the numerical model to assess the rockburst proneness. It was found that the criteria that are based on stress and strain changes were able to assess the rockburst proneness

L'objectif de ce travail est de contribuer à une meilleure prédiction de la rupture des Anévrismes de l'Aorte Abdominale. Pour ce faire, des simulations par éléments finis ont été mises en oeuvre sur des anévrismes modèles dans des conditions proches de la réalité physiopathologique, i.e. en tenant compte de l'anisotropie de la paroi anévrismale, du caractère poreux du thrombus et des Interactions Fluide-Structure. Dans la première partie, une étude statique en l'absence du thrombus a permis de mettre en évidence l'influence de la géométrie de l'anévrisme et du comportement mécanique (isotrope ou anisotrope) de la paroi sur la distribution des contraintes, i.e. la rupture potentielle de l'anévrisme, ainsi que sur l'évolution du module de Peterson. Dans la seconde partie, une modélisation poro-hyperélastique du thrombus est proposée, en s'appuyant sur des données expérimentales de la littérature. La prise en compte de ce comportement et des Interactions Fluide-Structure montre que la pression intra-thrombus demeure du même ordre de grandeur que la pression intra-luminale, conformément à des mesures in vivo réalisées par ailleurs. Enfin, nous montrons que ceci n'est pas en contradiction avec une réduction du risque de rupture potentielle de l'anévrisme. / The aim of this work is to contribute to a better prediction of the Abdominal Aortic Aneurysm rupture (AAA). For that purpose, finite elements simulations have been performed on idealized AAA models under physiopathological like conditions, by taking into account the aneurysmal wall anisotropy, the intra-luminal thrombus porosity and the Fluid-Structure Interactions. In the first part, the influence of the aneurysm geometry and its wall properties (isotropic or anisotropic hyperelasticity) on the wall stress distribution and the Peterson's modulus has been studied in a static analysis and without taking into account the thrombus. In the second part, based on the experimental results from the litterature, a porohyperelastic model has been proposed for the thrombus. By considering such behavior for the thrombus and the Fluid-Structure Interactions, we observe that the intra-thrombus pressure is the same order as the intra-luminal pressure, which is consistent with in vivo measurements. Our results show that despite this unchanged pressure, the maximum wall stress decreases leading to a decrease of the aneurysm potential rupture.

[pt] Prever o comportamento de estruturas de solo de grande porte, como barragens, durante a construção, em operação e inclusive sob o efeito de eventos sísmicos tem muita importância para evitar possíveis consequências catastróficas e indesejáveis. Neste sentido, este estudo apresenta, através de uma análise acoplada hidromecânica pelo método dos elementos finitos, os resultados numéricos discutidos em termos de tensões e suas trajetórias, deslocamentos verticais e horizontais, poropressões, incluindo a estabilidade de taludes. Além disso, é apresentada também a análise da resposta sísmica quando a estrutura é submetida a um carregamento dinâmico. Para tanto, analisou-se a barragem de terra zonada Recreta, situada na província de Huaraz - Peru, mediante o emprego do programa PLAXIS 2010. Foram descritas as metodologias de análise para simular passo a passo a construção incremental da barragem, o primeiro enchimento do reservatório por incrementos de níveis de água, o avanço da frente de saturação até atingir a condição de fluxo permanente e a avaliação da resposta dinâmica quando a barragem é submetida ao último maior movimento sísmico (história de acelerações) registrado em 1974 na capital do Peru, Lima, adjacente à cidade onde se localiza este projeto. Também se empregou o software Seismosignal versão 5.0, para o tratamento do sinal sísmico, e os programas Shake 2000 e Strata para a calibração dos parâmetros de amortecimento. Os resultados fornecidos por estas ferramentas numéricas foram avaliados em função do fundamento teórico, exposto na revisão bibliográfica, e de uma série de testes para o estabelecimento das metodologias e procedimentos mais adequados para a obtenção destes resultados. / [en] Predicting the behavior of soil structures, such as large-scale dams, during construction and operation, including the effect of earthquakes, is very important to prevent possible catastrophic and undesirable consequences. This study presents, through a coupled hydromechanical analysis by the finite element method, numerical results discussed in terms of stresses and trajectories, vertical and horizontal displacements, poropresssures and soil slope stability analyses. The investigation of the seismic response when the structure is subjected to a seismic load is also included, considering the dynamic behavior of the zoned earth dam Recreta, located in the province of Huaraz in Peru. The numerical analyses were carried out using the computational program PLAXIS 2010 to simulate the incremental construction of the dam, the first fill of the reservoir by increments of the water levels, the advance of the front of saturation until achieving the condition of steady flow condition and the seismic response when the dam is subject to the last major earthquake (accelerations history) registered in Peru s capital, Lima, in 1974, which is located near to the site of the Recreta dam. The Seismosignal software version 5.0 was also used for seismic signal processing and the programs SHAKE 2000 and STRATA were also employed for calibration of the damping parameters of the soils. All the results provided herein were discussed, based on the theoretical basics presented in the literature review as well as on the various numerical examples investigated with the main purpose to better understand the hydromechanical behavior of a zoned earth dam subject to static and dynamic loads.

De nombreuses études ont été menées sur les matériaux composites, concernant le comportement mécanique à l’échelle macroscopique. D’autre part, le développement continu des techniques de détection et de mesures de champs permet d’aller plus loin dans l’analyse des structures complexes, dont les matériaux composites. Ainsi, la corrélation volumique (DVC) basée sur des acquisitions de la structure interne à différents états de déformation, permet la mesure du champ des déplacements dans le volume des échantillons. Le gauchissement des sections dû aux contraintes de cisaillement transverse est un phénomène propre aux structures anisotropes comme les structures composites. De nombreuses études traitent du développement des modèles analytiques pour la modélisation numérique et la détermination des déplacements avec le plus de précision possible. Ainsi, de nombreux modèles existent, certains très complexes, pour la prise en compte de ce phénomène dans l’étude des structures multicouches. L'objectifs de ce travail doctoral est d’utiliser les mesures de champs issues de la corrélation volumique couplée à la tomographie rayons X, pour visualiser le gauchissement des sections pour un cas de sollicitation de flexion trois points. Une méthode de mesure ainsi qu’un système de chargement in-situ spécifique sont développés dans ce travail de recherche. Les modèles analytiques existants sont évalués et comparés à partir de mesures expérimentales. Aussi, un nouveau modèle est également proposé à partir d'une identification numérique, basée sur les mesures de champs volumiques réalisées. Les résultats de ce travail de thèse permettront une meilleure compréhension du phénomène physique rencontrés lors de l’utilisation des matériaux composites et pourront envisager des pistes d’optimisation de leur conception et de leur mise en œuvre. / The complex mechanical behaviour of composite materials, due to internal heterogeneity and multi-layered composition impose deeper analysis. Several studies have already been conducted on the composite structures mechanical behavior at the macro level. On the other hand, the continuous development of detection techniques and field measurements can now go further in the analysis of complex structures, including composites. Thus, the digital volume correlation (DVC) based on the acquisition of the internal structure at different deformation states, allows the measurement of displacement fields through the thickness of the specimen. Warping sections due to transverse shear is a phenomenon linked to anisotropic structures, such as composite structures, which has been the subject of many studies to develop analytical models for the numerical modeling and the determination of displacements with the greatest possible precision. Many theories and models exist, some very complex, for the consideration of this phenomenon .. One goal of this doctoral work is to use measurements from the density correlation to determine whether these models the effects of transverse shear are physically consistent, and if their validity is good in the case of a kinematic measurement volume. A second objective of this thesis is to acquire know-how in the processing of information resulting from acquisitions by X-ray tomography In this sense, several studies are planned for the treatment and use of this information in an industrial context. The results of this work will provide a better understanding of physical phenomena encountered in the use of composite materials to generate optimization of their design and implementation paths.

Cette thèse porte sur l’étude numérique de la dynamique des écoulements fluide-particules au sein des lits fluidisés denses. Le but de ces travaux est d’améliorer la compréhension des phénomènes qui s’y déroulent afin d’optimiser les performances des procédés industriels confrontés à ces écoulements diphasiques. En effet, la diversité des échelles de longueur et les différents types d’interaction fluide-solide et solide-solide rencontrées dans ce type de configuration rendent cette catégorie d’écoulement particulièrement complexe et intéressante à étudier. Le modèle développé à cet effet permet de suivre individuellement la trajectoire des particules et de traiter les collisions avec leurs voisines tandis que la phase fluide est décrite de façon localement moyennée. Dans ce mémoire, nous présentons tout d’abord les origines physiques du phénomène de fluidisation d’une population de particules et les grandeurs physiques qui le caractérisent. Puis nous détaillons le modèle Euler-Lagrange implémenté et présentons une série de tests de validation basés sur des résultats théoriques et des comparaisons à des résultats expérimentaux. Cet outil numérique est ensuite employé pour simuler et étudier des lits fluidisés comportant jusqu’à plusieurs dizaines de millions de particules. Enfin, nous comparons des simulations réalisées conjointement à l’échelle micro et avec le modèle développé au cours de cette thèse à l’échelle méso. / This thesis deals with numerical analysis of particulate flows within dense fluidized beds. The aim of this work is to improve phenomena understanding in such flows in order to optimize engineering processes design. Wide variety of length scales and various fluid-solid and solid-solid interactions makes complex and challenging this type of flows study. The present developed model permits individual particle tracking and handle particles collisions whereas fluid flow is space averaged. In this manuscript, we first present origins of fluidization phenomenon and describe the macroscopic quantities which characterize it. Then we introduce the Euler-Lagrange model we developed and detail its numerical implementation. Moreover, we present a bench of validation tests based both on theoretical results and experimental data comparison. This numerical tool is then used to simulate and study fluidized beds containing up to several tenth of millions particles. Finally, we compare simulations performed both at micro and meso scales, i.e. with the model developed during this thesis.