Permeable Friction Course (PFC) is a layer of porous asphalt pavement with a thickness of up to 50 millimeters overlain on a conventional impervious hot mix asphalt or Portland cement concrete roadway surface. PFC is used for its driver safety and improved stormwater quality benefits associated with its ability to drain rainfall runoff from the roadway surface. PFC has recently been approved as a stormwater best management practice in the State of Texas. The drainage properties of PFC are typically considered to be governed primarily by two hydraulic properties: porosity and hydraulic conductivity. Both of these hydraulic properties are expected to change over the life of the PFC layer due to clogging of the pore space by trapped sediment. Therefore, proper measurement of the hydraulic properties can be problematic. Laboratory and field tests are necessary for accurately determining the hydraulic conductivity of the PFC layer in order to ensure whether the driver safety and water quality benefits will persist in the future. During testing, PFC experiences a nonlinear flow relationship which can be modeled using the Forchheimer equation. Due to the two-dimensional flow patterns created during testing, the hydraulic conductivity cannot be directly measured. Therefore, numerical modeling of the two-dimensional nonlinear flow relationship is required to convert the measureable flow characteristics into the theoretical flow characteristics in order to properly determine the isotropic hydraulic conductivity. This numerical model utilizes a new scalar quantity, defined as the hydraulic conductivity ratio, to allow for proper modeling of nonlinear flow in two-dimensional cylindrical coordinates. PFC core specimens have been extracted from three different roadway locations around Austin, Texas for the past four years (2007 to 2010). Porosity values of the core specimens range from 12% to 23%, and the porosity data suggest a statistical decrease over time due to trapped sediment in the pore space. A series of constant head tests used in the laboratory and a falling head test used in the field are recommended for measurement of PFC hydraulic characteristics using a modified Forchheimer equation. Through numerical modeling, regressions equations are presented to estimate the hydraulic conductivity and nonlinear Forchheimer coefficient from the measureable hydraulic characteristics determined during experimental testing. Hydraulic conductivity values determined for laboratory core specimens range from 0.02 centimeters per second (cm/s) to nearly 3 cm/s. Field measurements of in-situ hydraulic conductivity vary over a range from 0.6 cm/s to 3.6 cm/s. The results of this research provide well-defined laboratory and field methods for measurement of the isotropic hydraulic conductivity of PFC experiencing two-dimensional nonlinear flow and characterized by the Forchheimer equation. This methodology utilizes a numerical model which presents a proper solution for nonlinear flow in two-dimensions. / text

Le mécanisme de Réduction Sélective de Perméabilité (RSP) résultant de l'adsorption de polymère ou d'un gel en milieu poreux a été largement reporté dans la littérature dans le domaine du régime de Darcy. Néanmoins, peu d'études ont été dédiées à l'impacte de l'adsorption de polymère en milieu poreux quand des écoulements diphasiques ont lieu en régime non-linéaire lesquels sont d'intérêt dans une large gamme d'applications. L'objectif de cette thèse est de présenter quelques résultats expérimentaux sur l'effet de l'adsorption d'une couche de polymère sur des écoulements gaz/eau à faible pression moyenne, i.e. quand l'effet Klinkenberg peut être considéré, aussi bien qu'à débits élevés quand les effets inertiels sont significatifs.<br /><br />L'étude expérimentale a consisté à l'injection d'eau et de diazote dans différents milieux poreux non consolidés de Carbure de Silicium (SiC) possédant des perméabilités différentes. Plus spécialement, notre objectif a été d'étudier des écoulements de gaz à différentes saturations en eau avant et après adsorption de polymère en régimes raréfié et inertiel. En bon accord avec les travaux précédents, en régime darcéen, nous observons une augmentation de la valeur de saturation irréductible en eau et une forte réduction de la perméabilité relative à l'eau, alors que celle au gaz est peu affectée. A faible pression moyenne dans la phase gazeuse, l'intensité de l'effet Klinkenberg est fortement augmentée avec la saturation en eau en l'absence de polymère, alors que, pour une même saturation, la présence d'une couche de polymère adsorbé réduit cet effet. En régime inertiel, une réduction des effets inertiels est observée quand le gaz est injecté après adsorption de polymère en tenant compte des modifications en terme de saturation en eau et de perméabilité. Des données expérimentales sont discutées en accord avec des hypothèses proposées pour expliquer ces effets.

Thesis (MScEng (Mathematical Sciences. Applied Mathematics))--University of Stellenbosch, 2006. / When considering flow through porous media, different flow regimes may be identified. At very small Reynolds numbers the relation between the pressure gradient and the velocity of the fluid is linear. This flow regime ...

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.

Ce travail de thèse a pour objectif l'étude des propriétés acoustiques de systèmes incorporant des plaques micro-perforées (MPP) et des matériaux absorbants sous forts niveaux d'excitation.Le premier chapitre traite des systèmes composés d'une MPP couplée à une cavité d'air et une paroi rigide. Un modèle analytique intégrant deux paramètres adimensionnels et un nombre de Mach optimal est présenté. La particularité de ce modèle est de décrire la variation du maximum du coefficient d'absorption (coefficient d'absorption à la résonance) avec l'augmentation du niveau d'excitation. Une formule proposée permet de prédire les variations du pic d'absorption avec le nombre de Mach acoustique.Les effets d'interaction entre les perforations sont étudiés sous forts niveaux d'excitation dans le deuxième chapitre. Un modèle basé sur l'approche fluide équivalent est proposé. Dans ce modèle, la tortuosité est corrigée pour prendre en compte les distorsions d'écoulement dues aux effets d'interaction entre perforations et aux effets de turbulence. Cette correction de tortuosité qui n'intègre permet de prédire le comportement de la réactance du système.Les multi-couches composés de MPP et de matériaux poreux sont l'objet d'étude du troisième chapitre. Chaque couche du système est modélisée à forts niveaux d'excitation suivant une loi de Forchheimer. Les différents matériaux sont décrits par la méthode de la matrice de transfert. Le cas où le multi-couche est directement collé à une paroi rigide et le cas où il y a une cavité d'air avant la paroi rigide sont examinés.Dans le dernier chapitre, l'étude sur la transparence acoustique à forts niveaux est initiée. Les perspectives de ce travail sont nombreuses et prometteuses pour l'acoustique des transports. / This work deals with the acoustical properties of systems incorporating Micro-Perforated Panels (MPP) and absorbing materials under high level of excitation.In the first chapter, absorbent systems composed of an air-cavity backed MPP are studied at high level of excitations. An analytical model involving two dimensionless parameters and an optimum Mach number is proposed. This model describes the behavior of the maximum of absorption coefficient (absorption coefficient at the resonance) with respect to the Mach number inside the perforations. A formula is proposed that predicts the variations of the absorption peak with the acoustical Mach number.In the second chapter, the holes interaction effects are studied theoretically and experimentally under high levels of excitations. Following an equivalent fluid approach, a model for which the tortuosity is corrected to account for the holes interaction effects coupled to the jet-like effects is developed. Multi-layered absorbents composed of MPP and porous materials are then studied under high level of excitations. The case where the multi-layers are directly attached to a rigid wall and the case where there is an air cavity before the rigid wall are examined. Forchheimer's law is used to model each medium of the multi-layer and the use of the transfer matrix method is made to account for these media.Sound transmission study under high level of excitation is introduced. The perspectives of this work are numerous and promising in the acoustics of transportation systems applications.

Les aquifères fissurés de type karst contiennent d'importantes ressources en eau. Ces aquifères sont complexes et hétérogènes sur une gamme d'échelles importantes. Leur gestion nécessite l'utilisation d'outils et de méthodologies adaptés. Dans le cadre de cette étude, différents outils et méthodologies numériques d'étude ont été développés pour la modélisation des aquifères karstiques, et plus généralement, des milieux poreux très fissurés 2D et 3D - en mettant l'accent sur la morphologie et sur le comportement hydrodynamique du milieu à travers la notion de changement d'échelle ("second changement d'échelle", reposant sur un modèle d'écoulement local de type Darcy et/ou Poiseuille avec quelques généralisations). Plusieurs axes sont explorés concernant la morphologie du milieu poreux fissuré (milieux aléatoires, milieux booléens avec réseaux statistiques de fissures, mais aussi, modèles morphogénétiques). L'étude du changement d'échelle hydrodynamique tourne autour du concept de macro perméabilité. Dans un premier temps, l'étude porte sur un modèle de perte de charge linéaire darcien. Les perméabilités effectives sont calculées numériquement en termes des fractions volumiques de fissures et du contraste de perméabilité matrice/fissures. Elles sont analysées et comparées à des modèles théoriques (analytiques). Une étude particulière des effets de quasi-percolation pour les grands contrastes aboutit à la définition de trois fractions critiques liées à des seuils de percolation. Pour tenir compte des effets inertiels dans les fissures, l'étude est étendue au cas d'une loi locale comprenant un terme quadratique en vitesse (Darcy/Ward-Forchheimer). Une perméabilité macroscopique équivalente non linéaire est définie et analysée à l'aide d'un modèle inertiel généralisé (linéaire/puissance). Enfin, l'anisotropie hydraulique à grande échelle du milieu fissuré est étudiée, en termes de perméabilités directionnelles, à l'aide d'une méthode numérique d'immersion. / Karstic aquifers contain large subsurface water resources. These aquifers are complex and heterogeneous on a large range of scales. Their management requires appropriate numerical tools and approaches. Various tools and numerical methodologies have been developed to characterize andmodel the geometry and hydraulic properties of karstic aquifers, more generally, of highly fissured 2D and 3D porous media. In this study, we emphasize morphological characterization, and we analyze hydrodynamic behavior through the concept of upscaling ("second upscaling"). Concerning the morphology of fissured porous media, several axes are explored : random media, composite random Boolean media with statistical properties, and morphogenetic models. Hydrodynamic upscaling is developed using the macro-permeability concept. This upscaling method is based on either Darcy's linear law, or on a linear/quadratic combination of Darcy's and Ward-Forchheimer's quadratic law (inertial effects). First, the study focuses on Darcy's linear head loss law, and Darcian effective permeabilities are calculated numerically in terms of volume fractions of fissures and "fissure/matrix" permeability contrasts. The results are analysed and compared with analytical results and bounds. A special study of percolation and quasi-percolation effects, for high contrasts, leads to defined three critical fractions. These critical fractions are "connected" to percolation thresholds. Secondly, in order to consider inertial effect in fissures, the study is extended to a local law with a quadratic velocity term (Darcy/Ward-Forchheimer). Then, an equivalent nonlinear macroscopic permeability is defined and analysed using a generalized inertial model (linear/power). Finally, the large scale hydraulic anisotropy of fissured medium is studied, in terms of directional permeabilities, using an "immersion" numerical method.

L'objectif de cette thèse est de contribuer à une meilleure compréhension du fonctionnement hydraulique d'un système de nappe superficielle de fond de vallée, alimentée par un versant et drainée par un fossé en régime transitoire. Ceci doit aboutir à terme à un outil de modélisation permettant de tester des scénarios de gestion ou d'aménagements de ces zones humides. Le parti (pari ?) choisi a été de fonder les efforts de modélisation sur l'approche " saturée 1D " (équation de Boussinesq), tout en utilisant des modèles plus sophistiqués (Laplace, Richards) afin de servir de référence lors de la discussion et l'élaboration des hypothèses simplificatrices. En particulier, certaines conditions aux limites ont été étudiées : (i) hétérogénéité de la recharge de la nappe ; (ii) déterminisme des phénomènes de surface de suintement ; (iii) l'affleurement ; (ij) une condition aval transitoire. Des expérimentations ont été menées sur modèle physique au laboratoire (maquette MASHyNS) et sur le terrain (bassin versant du Ru de Cétrais, Loire Atlantique). Un modèle (SIDRA 2+), fondé sur une résolution numérique de l'équation de Boussinesq, a été utilisé et adapté à la prise en compte des conditions aux limites particulières évoquées. Le modèle a été calé et validé à partir des données expérimentales et a permis de prédire avec une excellente précision la position de la surface libre de la nappe à différentes distances du ru de Cétrais, en période hivernale.

Pulse tube cryocoolers (PTC) are a class of rugged and high-endurance refrigeration systems that operate without moving parts at their low temperature ends, and are capable of reaching temperatures down to and below 123 K. PTCs are particularly suitable for applications in space, guiding systems, cryosurgery, medicine preservation, superconducting electronics, magnetic resonance imaging, weather observation, and liquefaction of gases. Applications of these cryocoolers span across many industries including defense, aerospace, biomedical, energy, and high tech. Among the challenges facing the PTC research community is the improvement of system efficiency, which is a direct function of the regenerator component performance. A PTC implements the theory of oscillatory compression and expansion of the gas within a closed volume to achieve desired refrigeration. An important deficiency with respect to the state of art models dealing with PTCs is the limited understanding of the hydrodynamic and thermal transport parameters associated with periodic flow of a cryogenic fluid in micro-porous structures. In view of the above, the goals of this investigation include: 1) experimentally measuring and correlating the steady and periodic flow Darcy permeability and Forchheimer’s inertial hydrodynamic parameters for available rare-Earth ErPr regenerator filler; 2) employing a CFD-assisted methodology for the unambiguous quantification of the Darcy permeability and Forchheimer’s inertial hydrodynamic parameters, based on experimentally measured steady and periodic flow pressure drops in porous structures representing recently developed regenerator fillers; and 3) performing a direct numerical pore-level investigation for steady and periodic flows in a generic porous medium in order to elucidate the flow and transport processes, and quantify the solid-fluid hydrodynamic and heat transfer parameters. These hydrodynamic resistances parameters were found to be significantly different for steady and oscillatory flows.