[pt] O presente trabalho foca em uma investigação numérica do escoamento através de meios porosos com macroporos, como os carbonatos. A presença de vugs e fraturas tem um forte efeito na característica do escoamento. O fluxo através da matriz porosa é geralmente descrito pela equação de Darcy e o fluxo através dos macroporos pela equação de Stokes. O acoplamento entre essas duas abordagens distintas traz grande complexidade para a modelagem de tais fluxos. Neste trabalho, utilizamos a formulação de Brinkman que é capaz de descrever ambos os fluxos através da matriz porosa e macroporos com uma única equação diferencial. Resolvemos o sistema de equações diferenciais usando o modelo de elementos finitos e implementamos o código com auxílio da plataforma FEniCS. Primeiro, resolvemos o fluxo 1-D através de placas paralelas com uma das paredes sendo um material poroso. O objetivo foi comparar as previsões obtidas pela formulação de Brinkman com aquela obtida usando a condição de contorno de Beavers-Joseph. Então, resolvemos um fluxo 2-D através de um meio poroso com macroporos. A geometria da estrutura porosa foi obtida a partir de cortes 2D de imagens tomográficas de carbonatos. O objetivo desta análise foi avaliar uma permeabilidade equivalente em função da área e estrutura dos macroporos. / [en] The present work focuses on a numerical investigation of the flow through porous media with macropores, such as carbonates. The presence of vugs and fractures have a strong effect on the flow characteristics. The flow through the porous matrix is usually described by the Darcy equation and the flow through the macropores by Stokes equation. The coupling between these two distinct approaches brings great complexity to the modeling of such flows. In this work, we use Brinkman formulation that is able to describe the flow, both in the porous matrix and macropores with a single differential equation. We solved the set of differential equations using the finite element model and implemented the code in the FEniCS platform. We first solved the 1-D flow through parallel plates with one of the walls being a porous material. The goal was to compare the predictions obtained with the Brinkman formulation to that obtained by using the Beavers-Joseph boundary condition. Then, we solved a 2-D flow through a porous medium with macropores. The geometry of the pore structure was obtained from 2D slices of tomographic images of carbonates. The goal of this analysis was to evaluate an equivalent permeability as a function of macropores area and structures.

Le contexte énergétique international impose de nouvelles orientations au secteur du bâtiment neuf ou en rénovation. Toute nouvelle solution doit être techniquement efficace et respectueuse pour l’environnement. Il s'agit dans ce travail de thèse de réaliser une étude numérique et expérimentale de matériaux de construction biosourcés liés au contexte transfrontalier Lorrain (France-Belgique- Luxembourg). En effet, ce travail intègre une partie du projet européen « Ecotransfaire » mené pour le développement d'une filière durable propre aux éco-matériaux. La sélection des matériaux selon une liste de critères à la fois scientifiques, géographiques et environnementaux a permis de répondre à notre problématique en s'orientant vers l'intégration des matériaux biosourcés pour leurs aspects favorables à l'environnement et à l’efficacité énergétique du bâtiment. Intégrés au bâtiment, ces matériaux sont sujets à plusieurs phénomènes de transfert de chaleur et de masse. Dans un premier temps et pour mieux appréhender ces phénomènes, un modèle de transfert couplé de chaleur, d'air, d'humidité (HAM transfers) est utilisé pour simuler le comportement hygrothermique d’un matériau en bois massif à structure supposée homogène. Ce modèle, mis en œuvre et résolu par la méthode des éléments finis, a été validé par des résultats analytiques retenus dans la littérature. L'étude de sensibilité du modèle au couplage, aux dimensions dans l'espace, aux conditions aux limites et aux variabilités des paramètres d'entrée est également présentée. Une des difficultés de l’utilisation de ce modèle réside dans la prise en considération de l'aspect fortement hétérogène de certains matériaux. Ainsi, dans ce travail, nous proposons une approche de caractérisation d'un composite lignocellulosique hétérogène de structure poreuse. En effet ce matériau est composé de deux constituants bien connus dans le domaine de l’industrie de construction: Le bois et le ciment. Le bois est incorporé sous forme de granulats avec des formes et des tailles irrégulières et le ciment est utilisé comme un liant. Le travail réalisé permet de remonter aux propriétés intrinsèques équivalentes de ce matériau (conductivité thermique et perméabilité à la vapeur) à l’aide des techniques de micro-tomographie. La méthodologie suivie consiste à la détermination de la structure d'échantillon par une prise d'images à l'échelle microscopique. Une fois la structure de l’échantillon générée, une reconstruction de la représentation bidimensionnelle précède la génération de la structure tridimensionnelle à l'aide d’un outil numérique qui permet de déterminer les propriétés équivalentes des domaines reconstruits en 3D. La perméabilité et la conductivité thermique équivalentes sont les deux propriétés évaluées dans cette configuration. Ces deux propriétés dépendent fortement de la porosité et de la distribution des pores dans la phase continue (la phase solide). De plus la composition de ce matériau et les fractions volumiques de chacun de ses constituants influent sur la formation de sa microstructure et par conséquent sur ses propriétés de transferts thermiques et hydriques. L'ensemble des connaissances développées dans ce travail permet une piste sérieuse pour l'élaboration d'un éco-matériau à propriétés contrôlées pour des usages spécifiques dans la construction et la rénovation / International energy context requires a new orientation to the building sector as in construction or in renovation. Any new solution must be technically efficient and environmentally acceptable. In this thesis, the object is to achieve a numerical and experimental analysis of a building biobased materials. Some of these materials are included from the study of a transborder project to the Lorraine region (France, Belgium and Luxembourg). Indeed an Ecotransfaire project was included in this work. This project has been oriented to the development of a sustainable eco materials chain. A process of analysis has been established in order to select the materials candidates on the basis of scientific, geographical and environmental criteria. The answers are moving towards the integration of bio-based materials. These materials are subject of several heat and mass transfers phenomena. So understanding these mechanisms within a building material has been achieved firstly. This resulted on a coupled model of heat transfer, air, moisture experienced by the HAM model. This model is applied to a wooden building material whose its structure is assumed homogeneous. Then, this model was implemented and solved by the finite element method. Its numerical solution is validated by analytical results available in the literature. The study of sensitivity of the model coupling, dimensions in space, the boundary conditions and the variability of input parameters is also presented. One of the difficulties of using this model is the case of heterogeneous materials. Thus, in this work, we propose an approach of characterization of a heterogeneous lignocellulosic composite material with a porous structure. In fact, this material is composed of two components: Wood and cement. The wood is presented by a shapes aggregates with irregulars sizes and the cement is considered as the binder in the composition. The object was to predict its equivalent intrinsic properties (thermal conductivity and vapor permeability) by using the micro-tomography techniques.The methodology consists to determine the structure of the sample by taking images at the microscopic scale. Once the structure of the sample is generated, we will conduct from a reconstruction of the two-dimensional representation to a three dimensional structure by using a numerical tool which determines the equivalent properties of the 3D reconstructed domain. The permeability as well as the equivalent thermal conductivity are the two properties evaluated in this configuration. These two properties are strongly depend to the porosity and to pore distribution in the continuous phase (the solid one). Moreover the composition of the material and the volume fractions of each components influence the formation of microstructure and consequently the thermal and hydric transfers

Conselho Nacional de Desenvolvimento Científico e Tecnológico / As simulações computacionais tem sido amplamente empregadas no estudo do escoamento darciano e não-darciano em meios porosos consolidados e não-consolidados. Neste trabalho, através de uma nova formulação para a equação de Forchheimer, foram identificadas duas novas propriedades denominados fator de comportamento do fluido, que atua paralelamente a permeabilidade, e permeabilidade equivalente global, resultado da relação anterior. Este comportamento foi estudado e validado através da implementação de um aparato experimental e um código computacional baseado no modelo de regressão-linear que, além disso, demonstrou que o escoamento, ainda que em regime não darciano, comporta-se linearmente como a equação de Darcy, ainda que o coeficiente angular desta diminuiu de acordo com a faixa do número de Reynolds atingida, sendo esta dependente do tipo de leito empregado. Ainda neste trabalho, foi implementado o método de otimização R2W para estimar os parâmetros da equação de Kozeny-Carman a partir de dados experimentais obtidos por Dias et al, a fim de simular o escoamento darciano em meios porosos. Por fim, foi alcançada excelente concordância entre os dados simulados pelo método R2W / equação de Kozeny-Carman e os dados reais. / Computer simulations have been widely used in the study of Darcys flow and non-Darcy porous media in consolidated and non-consolidated. In this work, through a new formulation for the Forchheimer equation, we have been identified two new called Fluid Factor Behavior properties, which acts parallel to permeability, and overall equivalent permeability result of the previous relationship. This behavior has been studied and validated through implementation of an experimental apparatus and a computer code based on the linear regression model, moreover, it demonstrated that flow, even in non darciano system behaves linearly as the Darcy, however, the slope of this decreased according to the range of Reynolds numbers reached, this being dependent on the type of bed used. Although this work was implemented R2W optimization method to estimate the parameters of Kozeny-Carman equation from experimental data provided in the literature in order to simulate the darciano flow in porous media. Finally, it achieved excellent agreement between the data simulated by R2W method / Kozeny-Carman equation and actual data.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / As simulações computacionais tem sido amplamente empregadas no estudo do escoamento darciano e não-darciano em meios porosos consolidados e não-consolidados. Neste trabalho, através de uma nova formulação para a equação de Forchheimer, foram identificadas duas novas propriedades denominados fator de comportamento do fluido, que atua paralelamente a permeabilidade, e permeabilidade equivalente global, resultado da relação anterior. Este comportamento foi estudado e validado através da implementação de um aparato experimental e um código computacional baseado no modelo de regressão-linear que, além disso, demonstrou que o escoamento, ainda que em regime não darciano, comporta-se linearmente como a equação de Darcy, ainda que o coeficiente angular desta diminuiu de acordo com a faixa do número de Reynolds atingida, sendo esta dependente do tipo de leito empregado. Ainda neste trabalho, foi implementado o método de otimização R2W para estimar os parâmetros da equação de Kozeny-Carman a partir de dados experimentais obtidos por Dias et al, a fim de simular o escoamento darciano em meios porosos. Por fim, foi alcançada excelente concordância entre os dados simulados pelo método R2W / equação de Kozeny-Carman e os dados reais. / Computer simulations have been widely used in the study of Darcys flow and non-Darcy porous media in consolidated and non-consolidated. In this work, through a new formulation for the Forchheimer equation, we have been identified two new called Fluid Factor Behavior properties, which acts parallel to permeability, and overall equivalent permeability result of the previous relationship. This behavior has been studied and validated through implementation of an experimental apparatus and a computer code based on the linear regression model, moreover, it demonstrated that flow, even in non darciano system behaves linearly as the Darcy, however, the slope of this decreased according to the range of Reynolds numbers reached, this being dependent on the type of bed used. Although this work was implemented R2W optimization method to estimate the parameters of Kozeny-Carman equation from experimental data provided in the literature in order to simulate the darciano flow in porous media. Finally, it achieved excellent agreement between the data simulated by R2W method / Kozeny-Carman equation and actual data.