Les procédés d’élaboration de pièces composites par infusion de résine, malgré leurs nombreux avantages, peinent à s’imposer dans les phases de production industrielle en raison de difficultés pour les maitriser. Ainsi, en partenariat avec ESI Group, un modèle complet pour la simulation de ces procédés est développé à l’ENSM-SE depuis les travaux précurseurs de P. Celle.Nos travaux portent sur la généralisation de ce modèle afin de traiter des cas, ainsi que sur son extension à la simulation des écoulements « post-infusion ». L'approche repose sur un découpage du domaine en trois zones (drainant, préformes imprégnées, préformes sèches) consistant ainsi à coupler un écoulement de Stokes dans le drainant à un écoulement de Darcy dans les préformes. De plus, l'influence mutuelle de la résine sur le comportement des préformes et de la déformation des préformes sur la perméabilité est considérée, à travers la loi de Terzaghi et des lois exprimant la perméabilité en fonction de la fraction de fibres, paramètre accessible uniquement dans une approche 3D mécanique couplée. Enfin, le procédé est découpé en trois phases : compression initiale des préformes sèches, remplissage et « post-infusion ». Les méthodes numériques, développées dans ces travaux, s'appliquent à des cas réels d'infusion souvent mis de côté dans les publications récentes car inaccessibles, impliquant des perméabilités très faibles (~10-15 m²), un drainant fin (~1 mm) et des géométries complexes.Cette approche innovante a été implémentée dans un code de calcul industriel (ProFlotTM), validée analytiquement sur des cas tests et expérimentalement sur des cas industriel dans le cadre du projet européen INFUCOMP. / Composite manufacturing processes by resin infusion, despite their many benefits, struggle to establish themselves in the industrial production phases due to difficulties to control them. So, in partnership with ESI Group, a comprehensive model for the simulation of these processes is developed at the ENSM-SE since the pioneering work of P. Celle.Our work focuses on the generalization of this model to handle complex industrial cases in three dimensions, as well as its extension to “post-infusion” flow simulation. The approach is based on three domains decomposition of the field (Distribution medium, impregnated preforms, dry preforms) consisting in coupling a Stokes flow in the distribution medium with a Darcy flow in the preforms. In addition, the mutual influence of the resin on the preforms and of the preforms deformation on the permeability is considered, through Terzaghi’s law and models expressing the permeability as a function of the fibre fraction, data only accessible with a 3D coupled mechanical approach. Finally, the process is divided into three phases: initial compression of dry preforms, filling and “post-infusion”. The numerical methods developed in this work, apply to real infusion cases often discarded in recent publications, involving very low permeability (~10-15 m²), thin distribution medium (~ 1 mm) and complex geometries (3D curved).This innovative approach has been implemented in an industrial simulation code (ProFlotTM), validated analytically over test cases and experimentally over industrial cases in the European project INFUCOMP.

Made available in DSpace on 2015-03-04T18:50:42Z (GMT). No. of bitstreams: 1 Apresentacao.pdf: 169709 bytes, checksum: 574c46462e9fcf63aa87693349129a55 (MD5) Previous issue date: 2006-11-29 / Conselho Nacional de Desenvolvimento Cientifico e Tecnologico / Estudamos problemas de Controle Ótimo de Sistemas de Parâmetros Distribuídos. O modelo consiste de uma equação diferencial parcial do tipo parabólica que modela o transporte de um poluente em um meio viscoso e incompressível, mais condições de contorno e condição inicial; ou seja, em nosso modelo estamos considerando além do termo difusivo, o termo convectivo. A modelagem matemática desenvolvida permite calcular a concentração do poluente que é despejada numa região do espaço, de forma que no tempo t=T, a concentração do poluente esteja o mais próximo possível da concentração máxima aceitável no meio. Mostramos a existência e unicidade de solução do sistema de estado e de um único controle ótimo sobre um conjunto de funções admissíveis. Caracterizamos o controle ótimo de forma a obter um sistema de otimalidade que permita o cálculo numérico do problema e mostramos a convergência do método. Provamos que o funcional de custo ótimo j(b)=J(u(b,t)) é diferenciável com derivadas parciais contínuas sobre um subconjunto convexo fechado U_ad do espaço de controles U. Como aplicação, estudamos o caso da contaminação de um rio/lagoa pelo mercúrio em água parada e em movimento.O objetivo maior desta parte do trabalho é minimizar, através dos controles, os efeitos causados pelos detritos do agente poluente. Na segunda parte deste trabalho, estudamos o problema de contato termoelástico que descreve as vibrações dinâmicas de uma viga que está engastada num de seus extremos enquanto o outro está livre e pode se mover entre dois obstáculos rígidos. O principal resultado desta parte do trabalho é mostrar a existência de solução do problema e que a energia associada ao sistema decai exponencialmente a zero quando o tempo vai para o infinito. Finalmente, em todos os casos, graficamos a solução do problema e analisamos os resultados.

In this thesis a multiscale mixed method aiming at the accurate approximation of velocity and pressure fields in heterogeneous porous media is proposed, the Multiscale Robin Coupled Method (MRCM). The procedure is based on a new domain decomposition method in which the local problems are subject to Robin boundary conditions. The method allows for the independent definition of interface spaces for pressure and flux over the skeleton of the decomposition that can be chosen with great flexibility to accommodate local features of the underlying permeability fields. Numerical simulations are presented aiming at illustrating several features of the new method. We illustrate the possibility to recover the multiscale solution of two wellknown methods of the literature, namely, the Multiscale Mortar Mixed Finite Element Method (MMMFEM) and the Multiscale Hybrid-Mixed (MHM) Finite Element Method by suitable choices of the parameter b in the Robin interface conditions. Results show that the accuracy of the MRCM depends on the choice of this algorithmic parameter as well as on the choice of the interface spaces. An extensive numerical assessment of the MRCM is conduct with two types of interface spaces, the usual piecewise polynomial spaces and the informed spaces, the latter obtained from sets of snapshots by dimensionality reduction. Different distributions of the unknowns between pressure and flux are explored. The results show that b, suitably nondimensionalized, can be fixed to unity to avoid any indeterminacy in the method. Further, with both types of spaces, it is observed that a balanced distribution of the interface unknowns between pressure and flux renders the MRCM quite attractive both in accuracy and in computational cost, competitive with other multiscale methods from the literature. The MRCM solutions are in general only global conservative. Two postprocessing procedures are proposed to recover local conservation of the multiscale velocity fields. We investigate the applicability of such methods in highly heterogeneous permeability fields in modeling the contaminant transport in the subsurface. These methods are compared to a standard procedure. Results indicate that the proposed methods have the potential to produce more accurate results than the standard method with similar or reduced computational cost. / Nesta tese é proposto um método misto multiescala visando a aproximação precisa de campos de velocidade e pressão em meios porosos altamente heterogêneos, o método Multiscale Robin Coupled Method (MRCM). Este procedimento é baseado em um novo método de decomposição de domínio no qual os problemas locais são definidos com condições de contorno de Robin. O método permite a definição independente de espaços de interface para pressão e fluxo sobre o esqueleto da decomposição que pode ser escolhida com grande flexibilidade para acomodar características locais dos campos de permeabilidade subjacentes. Simulações numéricas são apresentadas visando ilustrar várias características do novo método. Ilustramos a possibilidade de recuperar a solução multiescala de dois métodos bem conhecidos da literatura, a saber, o Multiscale Mortar Mixed Finite Element Method (MMMFEM) e o Multiscale Hybrid-Mixed (MHM) Finite Element Method por escolhas adequadas do parâmetro b nas condições da interface de Robin. Os resultados mostram que a precisão do MRCM depende da escolha deste parâmetro algorítmico, bem como da escolha dos espaços de interface. Uma extensa avaliação numérica do MRCM é conduzida com dois tipos de espaços de interface, os usuais espaços polinomiais por partes e os espaços informados, este último obtidos a partir da redução de dimensionalidade de conjutos de espaços de snapshots. Diferentes distribuições de incógnitas entre pressão e fluxo são exploradas. Os resultados mostram que b, adequadamente adimensionalizado, pode ser fixado em unidade para evitar qualquer indeterminação no método. Além disso, com ambos os tipos de espaços, observa-se que uma distribuição equilibrada de incógnita entre pressão e fluxo nas interfaces torna o MRCM bastante atraente tanto em precisão quanto em custo computacional, competitivo com outros métodos multiescala da literatura. As soluções MRCM são, em geral, apenas globalmente conservativas. Dois procedimentos de pós-processamento são propostos para recuperar a conservação local dos campos de velocidade multiescala. Investigamos a aplicabilidade de tais métodos em campos de permeabilidade altamente heterogêneos na modelagem do transporte de contaminantes na subsuperfície. Esses métodos são comparados a um procedimento padrão da literatura. Os resultados indicam que os métodos propostos têm o potencial de produzir resultados mais precisos do que o método padrão com custo computacional similar ou reduzido.

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / One of the parameters involved in the design of pressurized hydraulic systems is the pressure drop of the pipes. This verification can be performed through the Darcy-Weisbach formulation, which considers a coefficient of loss of charge (f) that can be measured by the implicit Colebrook-White equation. However, for this determination it is necessary to use numerical methods. Numerous explicit approaches have been proposed to estimate the "f", with different precisions and complexity. Considering the above, the objective of this work is to analyze the explicit approximations of the pressure loss coefficient for pressurized conduits in relation to the Colebrook-White formulation, through the relative performance and error index, determining the most accurate ones so that they can replace the standard Implied for the turbulent flow regime. It was analyzed 29 explicit equations in the literature, determining the coefficient of loss of charge through Reynolds number values in the range of 4x10³ ≤ Re ≤ 108 and relative roughness of 10-6 ≤ Ɛ / D ≤ 5x10-2, obtaining 160 points for each equation, totaling 4800 points. Statistical analysis was performed by the performance index (Id) and the relative error (ER) of the explicit equations in relation to Colebrook-White. The equations of Chen (1979), Shacham (1980), Sonnad Goudar (2006), Buzzelli (2008), Vantankhah and Kouchakzadeh (2008), Fang et al. (2011) and Offor and Alabi (2016a) apply for the entire range of 4x10³ ≤ Re ≤ 108 and 10-6 ≤ Ɛ / D ≤ 5x10-2, and presented high “Id” and high precision, the latter being highlighted by extreme precision, which is indicated to replace the use of the Colebrook-White standard approximation. / Um dos parâmetros envolvido no dimensionamento de sistemas hidráulicos pressurizados é a perda de carga das tubulações. Essa verificação pode ser realizada através da formulação de Darcy-Weisbach, que considera um coeficiente de perda de carga (f) que pode ser mensurado pela equação implícita de Colebrook-White. Porém, para essa determinação é necessário utilizar métodos numéricos. Numerosas aproximações explícitas têm sido propostas para estimar o “f”, com diferentes precisões e complexidade. Diante do exposto, o objetivo desse trabalho é analisar as aproximações explícitas do coeficiente de perda de carga para condutos pressurizados em relação a formulação de Colebrook-White, através do índice de desempenho e erro relativo, determinando as mais precisas para que possam substituir a padrão implícita, para o regime de fluxo turbulento. Foi analisado 29 equações explícitas presentes na literatura, determinando o coeficiente de perda de carga através de valores do número de Reynolds na faixa de 4x10³ ≤ Re ≤ 108 e rugosidade relativa de 10-6 ≤ Ɛ/D ≤ 5x10-2, obtendo 160 pontos para cada equação, totalizando 4800 pontos. A análise estatística foi realizada pelo índide de desempenho (Id) e pelo erro relativo (ER) das equações explícitas em relação à Colebrook-White. As equações de Chen (1979), Shacham (1980), Sonnad Goudar (2006), Buzzelli (2008), Vantankhah e Kouchakzadeh (2008), Fang et al. (2011) e Offor e Alabi (2016a) se aplicam para todo intervalo de 4x10³ ≤ Re ≤ 108 e 10-6 ≤ Ɛ/D ≤ 5x10-2, e apresentaram elevado Id e elevada precisão, destacando-se a última por extrema precisão, sendo esta a indicada para substituir o uso da aproximação padrão de Colebrook-White.

Submitted by Joel de Lima Pereira Castro Junior (joelpcastro@uol.com.br) on 2016-07-25T20:27:38Z No. of bitstreams: 1 Fabio Moita.pdf: 3369547 bytes, checksum: 8fdd55ba00088fdc25924d22cd08e1e6 (MD5) / Approved for entry into archive by Biblioteca de Administração e Ciências Contábeis (bac@ndc.uff.br) on 2016-08-03T19:14:43Z (GMT) No. of bitstreams: 1 Fabio Moita.pdf: 3369547 bytes, checksum: 8fdd55ba00088fdc25924d22cd08e1e6 (MD5) / Made available in DSpace on 2016-08-03T19:14:43Z (GMT). No. of bitstreams: 1 Fabio Moita.pdf: 3369547 bytes, checksum: 8fdd55ba00088fdc25924d22cd08e1e6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Universidade Federal Fluminense. Pró-Reitoria de Gestão de Pessoas. Niterói, RJ / Atualmente no campo dos estudos organizacionais percebe-se uma grande presença de modelos e conceitos oriundos de países hegemônicos. Porém estes, quando aplicados no contexto social, econômico e cultural local, não apresentam a efetividade esperada. Diante disso, buscou-se neste trabalho uma abordagem pós-colonial, e a análise de conteúdo dos pensadores latino-americanos envolvidos com o tema. Isto revelou a influência da colonialidade nas ciências sociais. Para traçar um caminho alternativo, recorremos às reflexões de Darcy Ribeiro e suas intertextualidades com o pensamento social latinoamericano a fim de entendermos as razões da visão colonizada e buscarmos uma práxis livre e não subordinada aos poderes hegemônicos. / Actualmente en el campo de los estudios organizacionales se da cuenta una fuerte presencia de modelos y conceptos derivados de los países hegemónicos. Pero éstos, cuando se aplica a el contexto social, económico, y cultural local no tiene la efectividad esperada. Por lo tanto, en este estudio se buscó un enfoque postcolonial, y el análisis de contenido de los pensadores latinoamericanos que se ocupan de la cuestión. Esto reveló la influencia del colonialismo en las ciencias sociales. Para trazar una ruta alternativa, utilizamos las reflexiones de Darcy Ribeiro y su intertextualidad con el pensamiento social latinoamericano con el fin de comprender las razones de la visión colonizada y buscar una praxis libre y no sometida a los poderes hegemónicos.

L’objectif de notre étude est de modéliser un réservoir géothermique. Si nous supposons que le réservoir géothermique n’est composé que d’eau pure le transfert de matière et d’énergie est classiquement décrit par deux équations de conservation : la conservation de la matière et la conservation de l’énergie. À ces deux équations vient s’ajouter la vitesse du fluide classiquement donnée par la loi de Darcy tandis que les propriétés thermodynamiques, obtenues grâce à des équations théoriques ou empiriques (les équations d’état), ferment le modèle mathématique. Dès lors, ce modèle fermé, il existe différents schémas de résolution. Le premier est de résoudre en pression et température puis de procéder à un changement de variables lors du passage de monophasique à diphasique ou de diphasique à monophasique. TOUGH2 utilise le couple pression-saturation dans la zone diphasique.La seconde approche est de résoudre en pression et enthalpie afin d’accroître la stabilité lors de la transition entre l’état monophasique et l’état diphasique (voir Hydrotherm). Nous avons adopté la seconde option, résoudre en pression et enthalpie. De plus la résolution spatiale est faite avec les volumes finis.La modélisation d’un réservoir géothermique fait intervenir des équations fortement dépendantes l’une de l’autre. Cependant nous avons fait le choix de découpler la résolution afin de se libérer de la complexité de la résolution du système couplé. En effet, cette méthode possède l’avantage d’être moins consommatrice de mémoire puisque nous travaillons toujours avec le même nombre de données, mais dans une matrice deux fois moins importante. Nous montrerons que cette méthode demeure suffisamment précise pour une utilisation aussi bien dans le domaine industriel que dans celui de la recherche.Nous offrons à l’utilisateur une grande liberté grâce à l’implémentation de plusieurs méthodes : Euler implicite, explicite, Runge-Kutta ou BDF2 pour les solveurs temporels ou GMRES et BICGSTAB pour les solveurs linéaires. Nous pouvons gérer des conditions aux limites très variées telles que des flux nuls (décrivant une frontière qui n’échange pas de matière avec l’extérieur) ou une condition mixte (un Dirichlet sur la pression et un Dirichlet ou condition « sortie libre » sur la température… Cette dernière situation décrit une zone de recharge ou de décharge. Nous avons développé un outil multilangage : Python,Fortran et C++ (une implémentation de l’IAPWS provenant du projet freesteam incluant la zone supercritique). Tous ces langages sont orientés objet. L’IAPWS est l’outil permettant de calculer les propriétés physiques inconnues et par conséquent il ferme le système.Enfin nous avons appliqué le modèle sur le bassin parisien, France, sur plusieurs systèmes 1D et un autre système 2D réalisés par Coumou avec la plateforme CSMP++. Le bassin parisien est un réservoir exploité pour produire de la chaleur par le biais du pompage d’une eau à 70 _C et réinjecté à 40 _C. Les simulations 1D permettent de visualiser le déplacement d’un front de chaleur en haute enthalpie. La simulation 2D montre la convection naturelle de l’eau dans une faille. Chaque simulation a été comparée aux résultats obtenus avec un autre code (CSMP++, HYDROTHERM ou TOUGH2) et les résultats sont en accord. / The purpose of our study is to model a geothermal reservoir. When geothermal reservoirs are assumed to be composed of pure water, the transfer of mass and energy is classically described by two balance equations: the mass balance equation and the energy balance equation. In addition to those equations, fluid velocity is classically given by the Darcy law while thermodynamic properties, inferred from theoretical or empirical equations of state, are used to close the mathematical system. Once this system is closed, there exist different solutions. The first one is to solve for pressure and temperature with a variable switch to saturation in the two-phase region (e.g. TOUGH2). The second one is to solve for pressure and enthalpy to increase the stability of phase transition between single and two-phase states (e.g. Hydrotherm). We adopted the second option. We solve the system by using a splitting method — to get rid of the complexity of coupling equations — and a finite volume method for the spatial discretization. We offer some freedom to users thanks to the implementation of several methods like explicit or implicit Euler, Runge-Kutta or BDF2 for time solvers or GMRES and BICGSTAB for the linear solver. We can handle several boundary conditions like no-flow — describing a boundary which cannot exchange matter withthe exterior — or like a mixed-therm condition — a Dirichlet condition to the pressure and a Dirichlet or an outflow condition to the temperature in order to describe a recharge or a discharge zone — …Selecting object-oriented languages, we developed a multi-language framework, combining Python, Fortran and a C++ implementation of IAPWS (from the freesteam project) including the supercritical equations. To close the system physical propertiesare determined by the IAPWS- IF97 thermodynamic formulation. We’ve applied this simulation model to the dogger in Paris, France, to several onedimensional systems and a two-dimensional one made by Coumou with the CSMP++platform. The dogger is a reservoir exploited to produce heat by pumping water at 70 _C and reinjecting it in the reservoir at 40 _C. In the one-dimensional systems we wanted to observe the process of heat transfer from a higher temperature boundary to a smaller one in a high-energy domain. The last simulation shows the natural convection of water in a fault. For every simulation we compared the solutions we found with another code (TOUGH2 or CSMP++) and they agreed.

Les mécanismes responsables du transport hydrodynamique anormal (non-Fickéen) peuvent être rattachés à la complexité de la géométrie du milieu à l'échelle des pores. Dans cette thèse, nous étudions la dynamique des vitesses de particules à l'échelle des pores. À l'aide de simulations de suivi de particules effectuées sur un échantillon numérisé de grès de Berea, nous présentons une analyse détaillée de l'évolution Lagrangienne et Eulérienne et de leur dépendance aux conditions initiales. Le long de leur ligne de courant, la vitesse des particules montre un signal intermittent complexe, alors que leur sériede vitesses spatiales présente des fluctuations régulières. La distribution spatiale des vitesses des particules converge rapidementvers l'état stationnaire. Ces résultats dénotent un processus Markovienqui permet de prédire les fluctuations de vitesse dans le réseau poral.Ces processus, associés à la tortuosité et à la distance de corrélation de vitesse permettent de paramétrer un modèle de marche aléatoire dans le temps (CTRW) et de réaliser le changement d’échelle pour simuler le transport à l’échelle de Darcy. Le modèle, comme tout modèle issu d’un changement d'échelle, repose sur la définition d'un volume élémentaire représentatif (VER). Nous montrons qu’un VER basé sur les statistiques de vitesse permet de définir un support pertinent pour la modélisation du transport hydrodynamique pré-asymptotique à asymptotique, et ainsi d’éviter les limitations associées à l’équation d’advection-dispersionFickéenne. Cette approche est utilisée pour étudier l’impact de l’hétérogénéité du réseau poral sur le volume de mélange et la masse du produit d’une réaction bimoléculaire. / The mechanisms responsible for anomalous (non-Fickian) hydrodynamictransport can be traced back to the complexity of the medium geometry atthe pore-scale. In this thesis, we investigate the dynamics of pore-scaleparticle velocities. Using particle tracking simulations performed on adigitized Berea sandstone sample, we present a detailed analysis of theevolution of the Lagrangian and Eulerian evolution and their dependenceon the initial conditions. The particles experience a complexintermittent temporal velocity signal along their streamline while theirspatial velocity series exhibit regular fluctuations. The spatialvelocity distribution of the particles converges quickly to thesteady-state. These results lead naturally to Markov processes for theprediction of these velocity series.These processes, together with the tortuosity and the velocitycorrelation distance that are properties of the medium, allow theparameterization of a continuous time random walk (CTRW) for theupscaling of the transport. The model, like any upscaled model, relieson the definition of a representative elementary volume (REV). We showthat an REV based on the velocity statistics allows defining a pertinentsupport for modeling pre-asymptotic to asymptotic hydrodynamictransport at Darcy scale using, for instance, CTRW, thus overcomingthe limitations associated with the Fickian advection dispersionequation. Finally, we investigate the impact of pore-scale heterogeneityon a bimolecular reaction and explore a methodology for the predictionof the mixing volume and the chemical mass produced.

This thesis examines how three nineteenth-century British novels purvey and critique contemporary standards regarding social performance and reticence and the strains such standards place on those whose dispositions disincline them to conform to the regulations for decorum articulated in conduct books of the time. Utilizing the psychological lens of introversion and extroversion alongside the cognitive narrative theories of Alan Palmer and Lisa Zunshine, this thesis investigates the construction of individual character identities through the reading of interactions among multiple fictional minds in Charlotte Brontë’s Villette (1853), Jane Austen’s Pride and Prejudice (1813), and George Eliot’s The Mill on the Floss (1860).

Les procédés par infusion de résine consistant à infuser une résine liquide à travers un empilement de préformes fibreuses sous l’action d’une pression extérieure ap-pliquée à cet empilement. Un drainant peut être utilisé pour créer un lit de résine sur ou sous cet empilement fibreux. Ces procédés sont utilisés pour fabriquer des pièces minces utilisées dans l’aéronautique par exemple. Les caractéristiques physiques et mécaniques des pièces obtenues sont difficiles à prévoir et à contrôler. La simulation numérique peut donc aider à la maîtrise de ces procédés. Dans ce travail, un modèle numérique éléments finis est proposé pour simuler les procédés par infusion de résine. L’écoulement de la résine, considérée comme un fluide Newtonien incompressible, est décrit par les équations de Stokes dans le drainant (milieu très perméable), et par les équations de Darcy dans les préformes fibreuses (milieu faiblement perméable). Ce couplage Stokes - Darcyest réalisé par une approche monolithique, consistant à utiliser un seul maillage pour les deux milieux. La formulation mixte en vitesse - pression, est alors discrétisée par des éléments finis linéaire - linéaire, et stabilisée par une méthode multiéchelle dite "ASGS". L’interface entre Stokes et Darcy et le front de la résine sont chacun représentés par une fonction "Level-Set", et des conditions de couplage sont imposées sur l’interface qui sépare les deux milieux. Au cours du procédé, les préformes subissent de grandes déformations, que ce soit durant la phase de compaction, ou durant l’infusion de la résine. La pression de la résine fait alors gonfler les préformes. Les déformations des préformes sont traitées par une formulation Lagrangienne réactualisée établie en grandes déformations. Les préformes sèches ont un comportement élastique non linéaire, donné dans le sens transverse par l’expérience. L’effet de la résine sur les préformes humides est représenté par le modèle de Terzaghi. Lorsque les préformes se déforment, leur porosité et donc la perméabilité du milieu varient, affectant ainsi l’écoulement. La formule de Carman-Kozeny est utilisée pour relier porosité et perméabilité. Après avoir validé le couplage Stokes - Darcy par de nombreux cas tests et par la méthode des solutions manufacturées, diverses simulations 2D et 3D de procédés par infusion de résine sont présentées, incluant la déformation des préformes. Des comparaisons sont finalement faites avec succès entre simulation numérique et résultats expérimentaux dans un cas de géométrie simple. Des extensions à des cas tridimensionnels présentant des courbures et des variations d’inertie sont proposées en guise de perspectives. / Resin infusion-based processes are good candidates for manufacturing thin composite materials parts such as those used in aeronautics for instance. These processes consist in infusing a liquid resin into a stacking of fibrous preforms under the action of a mechanical pressure field applied onto this stacking where a stiff- distribution medium is also placed to create a resin feeding. Both physical and mechanical properties of the final pieces are rather difficult to predict and control. Numerical simulation are perfectly suited to master these processes. In the present work a numerical finite element modeling framework is proposed to simulate infusion processes. The flow of the assumed Newtonian resin is described in the distribution medium, a highly porous medium, through Stokes’ equations and through Darcy’s equations in the fibrous preforms, very low permeability media. This coupled Stokes-Darcy flow is modeled in a monolithic approach which consists in using a single mesh for both media. The mixed velocity- pressure formulation is then discretized by linear-linear finite elements, stabilized by a so-called ASGS multi-scale approach. Both Stokes-Darcy interface and fluid front are represented individually thanks to "Level-Set" functions, and some specific coupling conditions are prescribed on the interface separating both fluid and porous media. During the process, orthotropic preforms undergo finite strains, either during the compaction stage when resin is not yet present, or during resin infusion. Resin pressure then tends to make the preforms swell. Preforms deformations are represented through an updated Lagrangian formulation for finite deformations. Dry preforms possess a non-linear elastic behaviour in their transverse direction - across their thickness- given by existing experimental measurements. The effect of the presence of resin in the wet preforms is accounted for using a Terzaghi’s equivalent model. Also, when preforms deform their porosity will change, and so will their permeability, modifying the resin flow. A Carman-Kozeny model is then used to relate porosity and permeability. After the Stokes-Darcy coupling is validated both on numerous tests cases and using the method of manufactured solutions, various 2D and 3D simulations of injection and infusion-based processes are analyzed.The latter includ- ing preform deformations along with resin flow. Comparisons with existing experimental measurements permit to validate the approach on a simple geometry. Last, some ex- tensions to more complex 3D cases are proposed as outlooks, including curvatures and thickness variations.

As plantações florestais, historicamente, estão associada a intensos debates sobre o seu impacto na dinâmica da água do solo ou subterrânea. Nesse contexto, este trabalho buscou avaliar os possíveis impactos da mudança de cobertura do solo, de pastagem para eucalipto, sobre o aquífero freático em zona de afloramento do Sistema Aquífero Guarani. A área de pesquisa está localizada na bacia do Ribeirão da Onça, situada no município de Brotas, no centro-leste do Estado de São Paulo. Essa é monitorada desde 2004. Foram utilizados dois métodos para avaliar o impacto da mudança de uso do solo, o método iWTF e o método de Darcy. A partir desses métodos, estimou-se as taxas de recarga subterrânea, fluxo lateral, variação de armazenamento e percolação profunda. Além disso foram obtidas a variação do nível freático, espessura saturada e gradiente hidráulico horizontal para o aquífero na área de estudo. Durante os anos hidrológicos de 2005 a 2011, a recarga direta variou de 255 e 876 mm (iWTF), equivalente a 21% e 51% da precipitação anual correspondente. Após 2011, com a mudança de cobertura do solo de pastagem para eucalipto, não obstante os anos hidrológicos de 2012 e 2013 apresentarem precipitação próxima da média de longo período, a recarga direta foi estimada em cerca de 210 mm (2012) e 147 mm (2013), equivalentes a 13% e 10% da precipitação anual. A diminuição na recarga direta levou à redução da espessura saturada, variação do nível freático, gradiente hidráulico horizontal, fluxo lateral e armazenamento anual. Além disso, pode-se perceber que a plantação florestal está exercendo influência sobre a área de pastagem adjacente à plantação. Tem-se observado essa influência através da existência de fluxo transversal em direção à plantação florestal, o qual tem elevado o armazenamento no período de estiagem. Os resultados indicam que a plantação de eucalipto afetou significativamente o comportamento sazonal e anual do balanço hídrico na área de estudo. / Historically forest plantations are associated with intense debate about its impact on soil water dynamics or groundwater. Thus, the objective of this study was to evaluate the potential impacts of land cover change of pasture to eucalyptus on the groundwater in an outcrop zone of the Guarani Aquifer System. The study area is located in the Ribeirão da Onça watershed, located in the municipality of Brotas, in the center-east of the state of São Paulo. To assess the impact of land cover change, I used two methods: i. iWTF and ii. Darcy. From these methods, we estimated groundwater recharge rates, lateral flow, water storage variation and deep percolation. Furthermore, I obtained the water table variation, saturated thickness and horizontal hydraulic gradient into the aquifer in the study area. During the hydrological years 2005-2011, the direct recharge through the results of iWTF method varied between 256 and 876 mm, equivalent to 21% and 51% of the corresponding annual precipitation. After 2011, with the land cover change of pasture to eucalyptus, the direct recharge was computed at about 210 mm (2012) and 147 mm (2013), equivalent to 13% and 10% of the annual precipitation. I did not find significant difference in the annual precipitation in these years compared to the historical mean. Therefore, my findings have shown that the decrease of direct recharge are associated to the land cover change of pasture to eucalypts. The decrease in direct recharge leads to the reduction of saturated thickness, the water level variation, horizontal hydraulic gradient, lateral flow and annual storage. Moreover, it can be seen that the forest plantation has influenced the pasture area, adjacent to the plantation. It has been observed that influence through the existence of cross flow toward the forest plantation, which has high storage, especially in the dry season. The results indicate that the eucalyptus plantation significantly affected the seasonal and annual behavior of the water balance in the study area.