Thèses sur le sujet « Ecoulement multiphasique en milieux poreux »
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Fiorentino, Eve-Agnès. « Phénomènes électrocinétiques et transport multiphasique en milieux poreux ». Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAH008/document.
Texte intégralThe electrokinetic coefficient is simulated in a large range of salinities using the Lattice Boltzmann method in a 2-D channel. The effect of permittivity and viscosity is discussed. The validity of the Helmholtz Smoluchowski equation using strong zeta potentials is assessed. A model of bulk fluid conductivity is derived, taking into account the local variations of conductivity which have a significant impact in the presence of polyvalent counterions. Extended to unsaturated conditions, the model shows that the electrical charge density associated to the air-water interface is a key component. The coefficient shows a non monotonous behaviour, with an enhancement compared to the saturated state. The magnitude of this enhancement depends on the dynamic state of the bubbles, moving or entrapped. The multiphase transport aspect is associated to a numerical study of the influence of the sample geometry on the measurement of the capillary pressure / saturation relationships used in hydrology
Ha, Quoc Dat. « Modélisation multiéchelle du couplage adsorption-transport-mécanique dans les réservoirs de gaz de charbon : récupération assistée par injection de CO₂ ». Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0194.
Texte intégralCoal seam gas is an energy resource whose exploitation can be enhanced by injectingcarbon dioxide (CO₂), thus combining the production of methane (CH₄) and the storage of carbon dioxide produced by its combustion. The structure of the reservoir is considered to be a double-porosity medium with natural fractures (cleats) and a matrix containing a solid phase and nanopores (less than 2 nm in size) where the gas is stored by adsorption on the solid wall. CO₂ is more easily adsorbed than CH₄. A multiscale theoretical model combining adsorption, transport and reservoir poro-mechanics is developed. At the smallest scale, the gas molecules are considered as hard spheres interacting through a Lennard-Jones potential. A new numerical method uses Density Functional Theory (DFT) and Fundamental Measure Theory (FMT) to calculate the distribution of molecular densities of a mixture of gases for any nanopore geometry. The solid wall exerts an external potential that is repulsive at very short distances and attractive at longer distances on the gas molecules. From the molecular distributions of the gases, the solvation force exerted by the fluid phase on the surface of the nanopores is precisely calculated. The asymptotic homogenization method is performed to upscale the nanopore-scale model and to obtain the response of the coal matrix at the microscale. The Biot poroelastic model is modified by the solvation force, which acts as the main factor governing matrix swelling or contraction. The average mass conservation equations for the two gases (CH₄ and CO₂) in the matrix take into account adsorption phenomena characterized by partition coefficients and an effective Knudsen-type diffusion. A second homogenization aims at obtaining the macroscopic law at the reservoir scaleby combining the cleats network and the solid matrix. The joint stiffness at the matrix-cleats interface is characterized by the hyperbolic Barton-Bandis law, which modifies the effective stiffness and the permeability of the reservoir. After homogenization, the reservoir is a heterogeneous and anisotropic medium due to the structure of the cleats and the spatial variation of the fluid pressure. A macroscopic average equation for gas diffusion in the matrix and gas-water transport in the cleats is developed by considering the mass exchange between the matrix and the cleats governed by the Warren and Root approximation. Numerical simulations illustrate the crucial correlation between gas pressure distributions, cleat opening and reservoir stiffness. CO₂ injection significantly improves CH₄ production and enables a underground storage of CO₂, which contributes to reducing green-house gas emissions
Pfertzel, Agnès. « Sur quelques schemas numeriques pour la resolution des ecoulements multiphasiques en milieu poreux ». Paris 6, 1987. http://www.theses.fr/1987PA066193.
Texte intégralCochard, Thomas. « Injection de tensioactif pour la récupération assistée du pétrole : implication sur les lois régissant les écoulements eau-hydrocarbure-tensioactif en milieu poreux ». Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066647/document.
Texte intégralThe main objective of the PhD is to study experimentally the oil mobilization using surfactant in a porous media below the residual oil saturation. At the residual oil saturation, the oil network is disconnected and organized in ganglia of different sizes and shapes all along the sample. This residual oil is difficult to produce in the classical conditions of water flooding because of capillary trapping created by the interfacial tension between oil and water. Injection of surfactant is able to mobilize the remaining oil at flow rates consistent with the real case of an oil mature reservoir. The use of surfactant allows lowering the interfacial tension by several orders of magnitude, towards ultra-low values (10-3 mN/m), strongly decreasing the capillary forces and so, mobilizing the oil. The first main study of the PhD work was to characterize the displacement of the surfactant injected in a sandstone sample in monophasic conditions (without oil). Breakthrough curves have been analyzed in term of dispersivity and adsorption. Experiments have shown that a better way to model the surfactant transport is to use a Langmuir kinetic adsorption model. For the diphasic case, we have developed a microfluidic 2D system with a random pore geometry of controlled conditions. The experiments are based on the injection of a small ganglia through a central channel, then, a surfactant flood is generated. The aim is to see how ganglia are displaced within the micromodel. New mechanisms have been identified and a way to model those phenomena has been proposed. A better understanding of surfactant and oil transport in porous media is key for chemical enhanced oil recovery processes
Amaziane, Brahim. « Homogénéisation et Modélisation Numérique d'Ecoulements en Milieux Poreux Hétérogènes. Applications à des Problématiques Energétiques et Environnementales ». Habilitation à diriger des recherches, Université de Pau et des Pays de l'Adour, 2005. http://tel.archives-ouvertes.fr/tel-00010339.
Texte intégralZitha, Pacelli. « Ecoulement non-stationnaire de polymeres hydrosolubles dans les milieux poreux ». Paris 6, 1994. http://www.theses.fr/1994PA066717.
Texte intégralCochard, Thomas. « Injection de tensioactif pour la récupération assistée du pétrole : implication sur les lois régissant les écoulements eau-hydrocarbure-tensioactif en milieu poreux ». Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066647.
Texte intégralThe main objective of the PhD is to study experimentally the oil mobilization using surfactant in a porous media below the residual oil saturation. At the residual oil saturation, the oil network is disconnected and organized in ganglia of different sizes and shapes all along the sample. This residual oil is difficult to produce in the classical conditions of water flooding because of capillary trapping created by the interfacial tension between oil and water. Injection of surfactant is able to mobilize the remaining oil at flow rates consistent with the real case of an oil mature reservoir. The use of surfactant allows lowering the interfacial tension by several orders of magnitude, towards ultra-low values (10-3 mN/m), strongly decreasing the capillary forces and so, mobilizing the oil. The first main study of the PhD work was to characterize the displacement of the surfactant injected in a sandstone sample in monophasic conditions (without oil). Breakthrough curves have been analyzed in term of dispersivity and adsorption. Experiments have shown that a better way to model the surfactant transport is to use a Langmuir kinetic adsorption model. For the diphasic case, we have developed a microfluidic 2D system with a random pore geometry of controlled conditions. The experiments are based on the injection of a small ganglia through a central channel, then, a surfactant flood is generated. The aim is to see how ganglia are displaced within the micromodel. New mechanisms have been identified and a way to model those phenomena has been proposed. A better understanding of surfactant and oil transport in porous media is key for chemical enhanced oil recovery processes
Chraïbi, Mehdi. « Modélisation de l'expansion de gaz dissous dans les huiles lourdes en milieu poreux ». Paris 6, 2008. http://www.theses.fr/2008PA066026.
Texte intégralId, Moulay Mohamed. « Simulation numérique 3D d'Écoulement Multiphasiques Réactifs en Milieux Poreux ». Thesis, Pau, 2019. http://www.theses.fr/2019PAUU3015.
Texte intégralReactive transport modeling is used in many energy and environmental applications related to subsurface flows. Modeling such problems leads to a highly nonlinear system of PDEs coupled with algebraic or ODEs. Two types of approaches for the numerical solving of reactive transport problems are widely used in the literature. One is the operator-splitting approach which consists in splitting the flow and reactive transport problems. These latter are solved sequentially at each time step. The other strategy is based on the fully coupled approach in which the entire system is solved simultaneously. The goal of the PhD thesis is the development of a fully coupled fully implicit finite volume scheme for numerical modeling of single and two-phase multicomponent flows with reactive transport in porous media. New reactive transport modules will be implemented in DuMuX, a free and open-source simulator for flow and transport processes in porous media. Numerical simulations for 2D and 3D including benchmark tests and high performance computing will be performed to validate the modules
Skachkov, Sergey. « Modèle macroscopique de la dispersion diphasique en milieux poreux et fracturés ». Thesis, Vandoeuvre-les-Nancy, INPL, 2006. http://www.theses.fr/2006INPL064N/document.
Texte intégralThe objective of the thesis is to develop the homogenized model of a two-phase flow through a porous and fractured medium by highlighting the dynamic mixing between the phases, caused by the medium heterogeneity. Attention is focused on the influence of the capillarity. The two-scale homogenization is applied. The mixing is manifested in form of the hydrodynamic dispersion and renormalized advection. The dispersion tensor, determined by the cell problem, is a nonlinear function of saturation, flow velocity, viscosity ratio and capillary number. For a fractured medium the method of streamline configurations was advanced for a two- phase case. This method enables to obtain the dispersion tensor and the effective permeability in analytical form for periodic fractured networks or in semi-analytical form for random networks. The simulation of two- phase displacement based on the new model is performed
Kuzhir, Pavel. « ECOULEMENT DES FLUIDES MAGNETIQUES DANS DES CAPILLAIRES ET MILIEUX POREUX SOUS L'EFFET D'UN CHAMP MAGNETIQUE ». Phd thesis, Université de Nice Sophia-Antipolis, 2003. http://tel.archives-ouvertes.fr/tel-00008824.
Texte intégralLe contrôle de l'écoulement est réalisé par l'effet du champ sur la surface libre ou sur la rhéologie de ces fluides et également par l'intermédiaire des forces magnétiques qui attirent le fluide dans les régions où le champ est le plus fort. On a établi les lois de comportement statique et dynamique de la surface d'un ferrofluide dans un capillaire en présence d'un champ magnétique homogène. Une diminution par un facteur deux du saut de pression sur le ménisque a lieu dans un fort champ longitudinal appliqué suivant l'axe du capillaire. La diminution du saut de pression dans un champ transversal induit un ralentissement de la pénétration capillaire du ferrofluide, ce qui permet de contrôler le temps de remplissage dans une plage de 60%.
On a généralisé le modèle de cisaillement simple d'un fluide MR, avec des agrégats en forme de chaînes, au cas d'un champ magnétique d'orientation quelconque par rapport à l'écoulement. Sur la base de ce modèle on a obtenu la dépendance théorique de la contrainte seuil dynamique en fonction de l'orientation du champ. Cette dépendance est utilisée pour calculer les profils de vitesse et les caractéristiques débit-pression dans des écoulements de Poiseuille d'un fluide MR dans des capillaires et des milieux poreux en présence d'un champ homogène d'orientation quelconque. Les courbes expérimentales débit-pression confirment bien la théorie et indiquent une possibilité d'augmenter la pression de trois ordres de grandeur.
On a appliqué un modèle d' écoulement biphasique pour simuler un blocage de l'écoulement d'un fluide MR dans un capillaire en présence d'une forte inhomogénéité de champ magnétique. Expérimentalement et théoriquement on a montré que la pression de blocage est à peu près 2 fois moins grande que la pression nécessaire pour relancer un écoulement bloqué.
Les résultats de ce travail forment une base théorique pour le développement de systèmes hydrauliques adaptatifs, et plus particulièrement de systèmes de vibroprotection.
Le, maout Vincent. « Modélisation d'écoulements multiphasiques de fluides viscoélastiques en milieux poreux ». Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0161.
Texte intégralViscoelastic multiphase flows in porous media are at the crossroad of many engineering sciences. Initiated with petroleum industry, their range of application is now extended to many additional areas, such as civil engineer-ing, geotechnics, composite impregnation and more recently life sciences. Mathematical formulations of these problems often rely on governing equations formulated directly at the macroscale, or are derived from micro-scopic considerations using upscaling technics. Generally, the second approach is prefered as it permits to estab-lish a clear connection between the scales of the porous media and to identify the restraining hypothesis neces-sary to the formulation of the equation system. However, when upscaling is performed, many unknown parameters remain to obtain a close set of equations, and additional closure relationships must be considered in order to find a solvable formulation. For the flows of interest, exhibiting multiphasic and viscoelastic properties, the usual macroscale empirical relations may be too inaccurate to capture relevantly the influence of underlying physics at play, and few experimental data allow characterising the missing parameters.A solution to this problem consists in performing numerical simulations at the microscale to extract missing information about media properties through microfluidic experiments in silico. To achieve this multi-scale modelling strategy, a pore scale model has been derived in this thesis for two applications of interest: improved oil recovery and tumor growth. The derivation of a unique model for these applications makes use of conservation equations at the microscale considered during upscaling operations. The obtained formulation allows a multiphase flow description by means of a phase-field method and the viscoelasticity of phases is introduced through the Oldroyd-B constitutive equation. The resulting mathematical model, implemented in a finite element code, permits to study in what extents the introduction of the polymer solution viscoelastic rheology during enhanced recovery process improves the mobilization of oil at pore scale. The influence of viscoelasticity on numerical solutions, as well as sweep efficiency of the medium, is compared to literature experimental results. On other hand, the mathematical model has been specialised to simulate the growth of a few hundred microns wide tumor aggregates. Since the precursor works of Steinberg the viscoelastic fluids analogy for cells aggregate is increasingly used for mathematical modelling. In this thesis, this similarity allows to study numerically the evolution of tumor aggregates in various environments. The biomechanical formulation of the problem permits to simulate cells population behaviour under mechanical load, which affects the growth rate according to the constraints in the system. In this context, the mathematical model is used to separate mechanical from biological effects, and provide original explanations on tumor growth in confined environment. The predictive capacity of the model on in vitro experiments shows the relevance of the viscoelastic multiphase flow for the tumor growth description
Abchir, Chakib. « Modélisation des écoulements dans les réservoirs souterrains avec prise en compte des interactions puits / réservoir (modélisation, simulation, étude mathématique) ». Saint-Etienne, 1992. http://www.theses.fr/1992STET4010.
Texte intégralGujisaite, Valérie. « Transport réactif en milieux poreux non saturés ». Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL056N/document.
Texte intégralThe aim of this work was to study the link between water flow and physical and chemical interactions in soils under variably water flow conditions, in order to improve the prediction of contaminants fate. It deals with understanding how the porous media water content can modify soil reactivity towards contaminants, and assessing the possibility to predict reactivity under unsaturated conditions with reactive solute transport studied in saturated porous media. Various processes were considered: cations exchange calcium-zinc on a model porous media (sand-kaolinite), sorption and desorption of an organic compound on a non polluted soil, transport of priority contaminants such as PAHs on an industrial contaminated soil. In each case, experiments were carried out with soil columns at the laboratory scale under saturated and unsaturated steady-state flow conditions, in order to characterize at first hydrodynamics and then to study the link with reactivity. Modeling of the breakthrough curves was then performed with codes such as CXTFIT. We showed an influence of porous media water content on reactive transport which was different as a function of the interaction. Porous media structure must also be taken into account. Ions exchange on a model porous media was not globally modified by the water content varying in a range close to saturation. On the contrary, higher sorption and lower migration of organic contaminants were observed under unsaturated conditions. Reactive transport of these compounds cannot therefore be predicted under unsaturated conditions with tests performed on saturated porous media which may overestimate transport
Muca, Lamy Edvina. « Ecoulement et transfert colloïdal dans des matrices hétérogènes et stratifiées : Application à des milieux poreux modèles ». Phd thesis, Ecole centrale de nantes - ECN, 2008. http://tel.archives-ouvertes.fr/tel-00363379.
Texte intégralHidani, Abdelkader. « Modélisation des écoulements diphasiques en milieux poreux à plusieurs types de rochesde roches ». Saint-Etienne, 1993. http://www.theses.fr/1993STET4029.
Texte intégralPieritz, Romeu André. « Modélisation et simulation de milieux poreux par réseaux topologiques ». Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10271.
Texte intégralCalugaru-Bozdog, Cerasela-Iliana. « Ecoulement et transport en milieux poreux : quelques problèmes directs et inverses pour des simulations d'interface fluide-fluide ». Besançon, 2003. http://www.theses.fr/2003BESA2058.
Texte intégralAgnaou, Mehrez. « Une étude numérique des écoulements mono et diphasique inertiels en milieux poreux ». Thesis, Paris, ENSAM, 2015. http://www.theses.fr/2015ENAM0050/document.
Texte intégralThis work focuses on inertial flow in porous media encountered in differentindustrial situations such as flow around wells in oil recovery, flow in filters and in columns ofreactors for chemical engineering, etc. In stationary flow regime, the different macroscopicmodels describing inertial (non-linear) flow are still discussed. These models consist in theDarcy’s law with correction extra terms whose dependence upon the filtration velocity is afunction of the flow regime. In this work, a particular attention is attributed first to the numericalinvestigation (DNS), on model structures, of the limit of one phase Newtonian stationary flowwhich corresponds to the first Hopf bifurcation, characterized by a critical Reynolds number.The knowledge of this limit is crucial since it establishes the ranges of validity of the relevantmacroscopic stationary models. In a second step, the dependence of the deviation (inertial)from Darcy’s law on the properties of the porous structure (grains shape, disorder) and on theorientation of the flow is analyzed in 2D and 3D situations. The effective properties of thestructure and the flow at the macroscopic scale are obtained from the numerical resolution ofthe closure problems associated to the macroscopic model obtained from an up-scalingprocedure (volume averaging) of the Navier-Stokes equations. In order to identify the origin ofthe deviation and its different forms, the variation of the microscopic flow structure with theReynolds number is analyzed. More specifically, the role of the recirculation zones, and thecorrelations with flow streamlines curvature multiplied by the local kinetic energy and thevariation of the kinetic energy along these lines are studied. The last part of the work isdedicated to a numerical investigation of the deviation from the generalized Darcy’s law in thecase of two phase inertial flow
Thovert, Jean-François. « Phenomenes de transfert dans les milieux poreux fractals : l'empilement apollonien ». Paris 6, 1987. http://www.theses.fr/1987PA066217.
Texte intégralMarusic-Paloka, Eduard. « Modélisation par homogénéisation des écoulements en milieux poreux fissurés ». Saint-Etienne, 1995. http://www.theses.fr/1995STET4008.
Texte intégralRAKOTOMALA, NICOLE. « Etude experimentale par acoustique de la dispersion hydrodynamique dans les milieux poreux ». Paris 7, 1988. http://www.theses.fr/1988PA077144.
Texte intégralBoutin, Claude. « Dynamique des milieux poreux saturés déformables : fonctions de Green, perméamètre dynamique ». Grenoble 1, 1987. http://www.theses.fr/1987GRE10026.
Texte intégralGeorgin, Eric. « Étude de l'effet piston au sein d'un fluide supercritique en milieux poreux ». Bordeaux 1, 2007. http://www.theses.fr/2007BOR13407.
Texte intégralSaber-Cherif, Walid. « Écoulements et rupture en milieu poreux déformable. Application au stockage géologique de CO2 ». Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066535/document.
Texte intégralUnderground carbon dioxyde (CO2) storage operation in deep geological formation like saline aquifers or gas reservoirs is considered to be a prospective solution to reduce the emission of greenhouse gases into the atmosphere. However CO2 sealing injection has to be assured for centuries. Once setting, the cement is a few centimeters thickness interface between the rock and the casing. This cementeous interface appears as the most critical point for the sealing and containment of CO2. A continuous stream of CO2 being injected into reservoir rock formation will cause in a region around the injection water desaturation and drying shrinkage of the reservoir and the cement paste and potentially hydraulic fracture. Therefore, the moisture balance with the CO2 reservoir induces water desaturation and drying shrinkage. Some local stresses are then expected because of the strain incompatibility between the cement and the steel casing and the high pressures levels. These stresses may result in a cracking process along the interface and in a secondary cracks network. In this context, we investigate how the poromechanical theory should be extended using a energy approach framework to describe the fracture mechanic induced by the fluid injection in a porous medium. The original idea of this approach consists in deriving the poro-mechanical equations introducing explicitly the multiphase flow. This model, aims at describing coupled flows in a damageable elastic porous medium, due to the combined influence of hydraulic and pressure gradients simultaneously imposed. The numerical implementation is based on a standard finite element discretization and adaptation of a eigenerosion model to simulate cracking
Oladyshkin, Sergey. « Découplage de la thermodynamique et hydrodynamique et solutions asymptotiques des problèmes d'écoulement compositionnel gaz-liquide en milieux poreux ». Thesis, Vandoeuvre-les-Nancy, INPL, 2006. http://www.theses.fr/2006INPL059N/document.
Texte intégralThe present work deals with the problem of the compositional gas-liquid flow for the well representation in reservoir simulations. The objective is to develop analytical relationships which would be able to link the wellbore pressure, saturation and component concentrations to their mean values within each zone of the well influence. It is shown that N-2 equations describing the transport of phase concentrations can be transformed into the space- and time-independent ordinary differential equations (differentiation with respect to pressure) when examined along flow streamlines. These transformed equations represent additional thermodynamic relations reducing the thermodynamic degree of freedom. Due to this the thermodynamic variance of the limit compositional model is shown to be equal to 1 for any number of chemical components. This transformation ensure a total splitting of the limit compositional model into the new thermodynamic model and a hydrodynamic model, which may be resoved inedpendently of one another. The split thermodynamic model is totally independent on the hydrodynamic one, and describes the equilibrium behaviour of an open gas-liquid system. This model contains the classic equilibrium equations and EOS, as well as N-2 new differential equations called the "delta-law" which determine the composition variation in an open system, in which the mass of each component is not conserved. The split hydrodynamic model consists of two equations for pressure and saturation. The split hydrodynamic model was used to develop asymptotic solutions of gas-condensate flow problems. The problem was shown to be singularly perturbed with formation of a boundary layer in the vicinity of the well. In this layer the basic contrast property of gas and liquid mobilities is perturbed. A special technique is developed which enables to construct asymptotic expansions in the form of two various series, one of them is valid far from the well (the exterior expansion), while the second one in valid in the vicinity of the well (the boundary-layer or interior expansion). By applying the suggested asymptotic method, we have developed the asymptotic solutions for the problem of multi-component gas-condensate flow to a well in a bounded domain at a variable flow rate. In several cases the solution may be obtained in the analytical form, while in general case of flow the method leads to a semi-analytical solution presented as an initial problem for a differential equation. This solution, even being presented in non-analytical form, is much simpler than the original compositional model, as the equation for saturation does not depend on the local pressure, but on the boundary pressure only. In the last chapter we extended this approach to the case when the capillary pressure is not neglected. We assumed however that the capillary forces are lower than the pressure difference between the wellbore and reservoir boundary, due to which we applied the perturbation method over the small inverse capillary number. The improved asymptotic solutions are obtained which take into account the capillary effect. Numerical simulations shown that these effects are maximal in the vicinity of the well. For the practice, the obtained asymptotic solutions may be used in the following way to resolve the problem of gas-condensate well representation. The case of a long-term exploitation of the reservoir}. First of all, the traditional simulation of the reservoir behaviour can be performed with ECLIPSE by adding the Peaceman method of well representation, which is an analytical relation for the wellbore pressure via the production rate. This relation includes a condensate saturation which can be evaluated as a mean reservoir saturation. Such a simulation provides a good result for the wellbore pressure (or the production rate), and a good result for the boundary saturation, but poor data for the wellbore saturation. This value can be calculated next by using the asymptotic solutions suggested in the presented project. The case of a short-term well production (a well test). It is sufficient to simulate the reservoir behaviour in the domain of the well influence, by assuming that the boundary state remains invariable (and known a priori). In this case the asymptotic solutions suggested in the presnet work can be directly used to simulate the problem (without using ECLIPSE)
Hennicker, Julian. « Discrétisation gradient de modèles d’écoulements à dimensions hybrides dans les milieux poreux fracturés ». Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4057/document.
Texte intégralThis thesis investigates the modelling of Darcy flow through fractured porous media and its discretization on general polyhedral meshes. We follow the approach of hybrid dimensional models, invoking a complex network of planar fractures. The models account for matrix-fracture interactions and fractures acting either as drains or as barriers, i.e. we have to deal with pressure discontinuities at matrix-fracture interfaces. In the case of two phase flow, we present two models, which permit to treat gravity dominated flow as well as discontinuous capillary pressure at the material interfaces. The numerical analysis is performed in the general framework of the Gradient Discretisation Method, which is extended to the models under consideration. Two families of schemes namely the Vertex Approximate Gradient scheme (VAG) and the Hybrid Finite Volume scheme (HFV) are detailed and shown to fit in the gradient scheme framework, which yields, in particular, convergence. For single phase flow, we obtain convergence of order 1 via density results. For two phase flow, the existence of a solution is obtained as a byproduct of the convergence analysis. Several test cases are presented. For single phase flow, we study the convergence on different types of meshes for a family of solutions. For two phase flow, we compare the hybrid-dimensional models to the reference equidimensional model, in which fractures have the same dimension as the matrix. This does not only provide quantitative evidence about computational gain, but also leads to deep insight about the quality of the proposed reduced models
Maghoul, Pooneh. « Solutions fondamentales en Géo-Poro-Mécanique multiphasique pour l'analyse des effets de site sismiques ». Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00599397.
Texte intégralGandola, Franck. « MMéthodologie de visualisation des écoulements en milieux non saturés : théorie et expériences ». Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10178.
Texte intégralAhmed, Selim. « Modélisation numérique de l'écoulement et du transport en milieux poreux : application de la méthode des lignes aux écoulements densitaires ». Strasbourg, 2009. http://www.theses.fr/2009STRA6051.
Texte intégralThe aim of this work is to develop robust numerical models for modelling flow and mass transfer in porous media. In the first part of this thesis, we developed a technique for improving the accuracy of quadrangular Mixed Hybrid Finite Elements. This technique allows to avoid non physical oscillations met when solving stiff problems with standard MHFE and to improve precision and CPU time. In the second part, we developed a robust numerical model with efficient advanced approximations for both spatial and temporal discretizations to solve the system of coupled equations flow-transport using the method of lines (MOL). For the space discretization, we combined the MHFEc method for the flow, MPFA for the dispersive term and DG for the advection term of the transport equation. For the temporal discretization of the resulting ODE system, tow solvers based on Backward Differential Formulas (BDF) methods, are used. DLSODIS (resp, DASPK), uses a direct method (resp, iterative method) for solving linear systems arising in each Newton iteration. With simulation of standard numerical test cases as well as a laboratory scale experiment we show, firstly, the efficiency, accuracy and robustness of the model based on DLSODIS solver. Secondly, the model based on DASPK solver is very suitable for solving large scale density driven flow systems. The new model allows temporal error control and reduces more than 30 times the computing time compared to the standard model
Ilina, Tatiana. « Modèles pseudo-diphasiques de transport facilité des colloïdes en milieux faiblement perméables ». Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL001N/document.
Texte intégralThe aim of this PhD thesis is to create and to develop a colloid suspension transport model in the saturated porous media that will be able to detect and to predict the apparition of the difference between water and suspension velocity; to distinguish cases of acceleration and of deceleration of the colloidal particles and also to calculate the two velocities using the initial information on the properties of porous media and of particles. We are proceeded by two different manners. Firstly, we are proposed an analytical method of calculation of enhancement velocity factor that can be introduced in the classic colloid transport model that is single-phase one. Secondly, we are proposed a new phenomenological mathematical approach to describe a colloid transport. To develop this approach, we are used the fact that two velocities appear automatically in the two-phase transport model. Thus our model must be similar to two-phase one. Therefore, for our mathematical model we are refused the traditional approach that assumes a transport of a single-phase liquid
Tognisso, Djivede Elvire. « Écoulements de fluides complexes en milieu poreux : utilisation de micelles géantes pour la Récupération Améliorée du Pétrole ». Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14347/document.
Texte intégralAmong all the Enhanced Oil Recovery (EOR) methods used to improve oil recovery, chemical methods require the use of complex fluids like polymers or surfactant solutions. Those fluids present particular chemical and mechanical properties allowing to modify viscosity and/or interfacial tension to increase oil recovery. However, polymer solutions show a high sensitivity to shear rates existing close to wells and may lose their mechanical properties when they are injected in a porous media. An alternative method could be to use self arrangement of surfactant molecules (wormlike micelles) to displace oil in porous media. These systems show not only a similar behaviour as polymers but also a low sensibility to temperature and shear rates.The goal of this experimental work is to study the flow of wormlike micelle solutions innatural porous media in order to determine its ability to flow and displace oil in place. Itconsists in a characterization at laboratoty scale. We will use natural porous media in orderto be close to a realistic situation. This study is divided in three parts:- A rheological characterization of the micellar system- A monophasic injection within the porous medium- A diphasic _ow study of oil displacementThe results of this work are compared to standard reference experiments using classicaltechniques such as ASP or polymer injection
Wang, Yunli. « Etude expérimentale et numérique des oscillations hydrodynamiques en milieux poreux partiellement saturés ». Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0127/document.
Texte intégralThis thesis aims at investigating experimentally, analytically and numerically, the consequences of hydrodynamic variations and oscillations with high temporal variability in partially saturated porous media. The problems investigated in this work involve “free surfaces” both outside and inside the porous media, the free surface being defined as the “atmospheric” water pressure isosurface (Pwater = Patm). The laboratory experiments studied in this work are, respectively: Lateral imbibition in a dry sand box with significant capillary effects; Transmission of oscillations of the free surface through a vertical sand box placed in a small wave canal (IMFT, Toulouse); Dynamics of free surface oscillations and wave propagation in a large wave canal (HYDRALAB, Barcelona), partially covered with sand, with measurements of both open water and groundwater levels, and of sand topography (erosion / deposition). For theoretical studies, we have developed linearized analytical solutions. Here is a sample problem that was treated analytically in this work: The linearized equation of Dupuit-Boussinesq (DB) for transient free surface flow, assuming horizontal flow and instantaneous wetting/drainage of the unsaturated zone: forced oscillations, wave transmission and dissipation through a rectangular sandbox. We also developed a weakly nonlinear solution of the Dupuit-Boussinesq equation to study the sudden imbibition (temporal monitoring of the wetting front). We have studied the different types of transient flow problems related to the experiments cited above by numerical simulation. In particular, we have simulated unsaturated or partially saturated transient flows in vertical cross-section, using a computer code (BIGFLOW 3D) which solves a generalized version of Richards’ equation. Thus, using the Richards / BIGFLOW 3D model, we have studied numerically the experiment of unsaturated imbibition in a dry sand (IMFT sandbox), and then, with the same model, we have also studied the partially saturated wave propagation experiment in the large Barcelona wave canal (HYDRALAB laboratory), focusing on the sloping sandy beach, with coupling between the micro-porous zone (sand) and the “macro-porous” zone (open water). To interpret the results of the latter experiment and compare them to simulations, we use several methods of signal analyzis and signal processing, such as: Fourier analysis, discrete multi-resolution wavelets (Daubechies), auto and cross-correlation functions. These methods are combined with pre-filtering methods to estimate trends and residuals (moving averages; discrete wavelet analyses). This signal analyzis has allowed us to interpret and quantify water propagation phenomena through a sandy beach. To sum up, different modeling approaches, combined with model calibration procedures, were applied to transient nonlinear coupled flow problems. These approaches have allowed us to reproduce globally the water content distributions and water level propagation in the different configurations studied in this work
Abadpour, Anahita. « Analyse asymptotique du problème de Riemann pour les écoulements compositionnels polyphasiques en milieux poreux et applications aux réservoirs souterrains ». Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL098N/document.
Texte intégralIn the first part of thesis we deal with two-phase multicomponent, partially miscible, compressible flow in porous media. Displacement of one phase by another is analyzed. We examine non ideal solutions, pressure is variable, and phase compositions, densities and viscosities are variable functions of pressure.The process is described by Riemann problem which admits discontinuous solutions.We developed a numerical-analytical method of solution to explicitly determine all shock parameters before solving the flow equations. This method is based on splitting thermodynamics and hydrodynamics, suggested in [Oladyshkin, Panfilov 2006]. Earlier this method was inapplicable to Riemann problem, due to the lack of Hugoniot conditions. In this thesis we have constructed additional Hugoniot conditions.In the second part we examine two-phase flow when the single-phase zones appear, in this zone the fluid is over/under-saturated and two-phase flow equations degenerate and they cannot be used. We proposed to describe two-phase and over/under-saturated single-phase zones by uniform system of classic two-phase equations while extending the concept of phase saturation to be negative and higher than one. Physically it means that the oversaturated single-phase states are considered as pseudo two-phase states consisting an imaginary phase with negative saturation. Such an extension of saturation requires developing some consistence conditions which have developed in this thesis.The last part then is devoted to extend the HT-split model to the case of three-phase compositional flow. We have obtained the general asymptotic model, in which the thermodynamics and hydrodynamics are split
Sciumè, Giuseppe. « Thermo-hygro-chemo-mechanical model of concrete at early ages and its extension to tumor growth numerical analysis ». Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00907395.
Texte intégralBoyer, Franck. « Modélisation, Analyse et Approximation numérique en mécanique des fluides ». Habilitation à diriger des recherches, Université de Provence - Aix-Marseille I, 2006. http://tel.archives-ouvertes.fr/tel-00104532.
Texte intégralUne première partie du travail concerne l'étude de modèles dits à interface diffuse pour les écoulements incompressibles multiphasiques. Après une étude assez précise du cadre diphasique, on propose la généralisation au cadre triphasique, ce qui nécessite d'introduire la notion importante de consistance des modèles. Des résultats numériques confirment la pertinence des modèles proposés. Ensuite, on s'intéresse au modèle plus classique de Navier-Stokes non-homogène incompressible pour lequel on établit le caractère bien posé du problème pour des conditions aux limites ouvertes non-linéaires en sortie d'un écoulement. Une brique essentielle de ce travail est l'étude détaillée du problème de traces pour l'équation de transport associée à un champ de vitesse peu régulier. Ce travail, dont l'intérêt dépasse le cadre applicatif décrit ci-dessus, fait l'objet d'un chapitre à part entière.
Dans une seconde partie, on s'intéresse à l'approximation numérique par des méthodes de volumes finis des solutions de problèmes elliptiques non-linéaires monotones (du type p-laplacien). Un premier chapitre décrit un certain nombre de résultats obtenus dans le contexte de maillages cartésiens. Un second chapitre est consacré à l'étude d'un cadre géométrique plus général par le biais de méthodes dites en dualité discrète. Une attention particulière est portée au cas où les coefficients du problème présentent des discontinuités spatiales, ce qui mène à des problèmes de transmission non-linéaire entre deux milieux.
Le mémoire s'achève par la description de quelques travaux connexes, d'une part sur une classe de schémas VF pour les équations elliptiques linéaires adaptés à des maillages non orthogonaux, et d'autre sur l'étude numérique de problèmes elliptiques couplés 2D/1D issus de la description asymptotique d'écoulements dans des milieux poreux fracturés.
Daadaa, Mouna. « Discrétisation spectrale et par éléments spectraux des équations de Darcy ». Paris 6, 2009. http://www.theses.fr/2009PA066397.
Texte intégralIstasse, Eric. « Contribution à l'étude de la dispersion hydrodynamique et de son couplage à la convection naturelle en milieux poreux modèles fracturés ». Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211181.
Texte intégralTrois problèmes physiques sont étudiés: tout d’abord le problème de Horton-Rodgers-Lapwood qui est l’équivalent du très connu problème de Rayleigh-Bénard mais pour un milieu poreux, ensuite les phénomènes de dispersion hydrodynamique que l’on rencontre dans des écoulements multiphasiques. Cette dispersion hydrodynamique est essentiellement envisagée comme un processus macroscopique de diffusion, renforcé par rapport à la diffusion moléculaire que l’on rencontre en milieu fluide libre. Enfin, le troisième problème englobe les écoulements capillaires en milieux poreux en environnement de pesanteur réduite. Dans le cas d’écoulements immiscibles multiphasiques, il faut prendre en considération l’effet de la tension superficielle aux interfaces. Comme les effets capillaires sont partiellement masqués par les effets de pesanteur durant des expériences au sol, une étude précise des effets de mouillage dans ces écoulements en milieu poreux nécessite de les découpler au maximum des autres effets physiques. Un programme de recherche en microgravité a été réalisé, et un nouveau modèle mathématique qui prend en compte l’influence des forces capillaires a été élaboré dans le cadre d’une collaboration entre le Service de Chimie-Physique et le Prof. N.N. Smirnov du Département de Mécanique et de Mathématique de l’Université d’Etat de Moscou.
La structure de ce travail part du Chapitre 1, qui présente essentiellement les milieux poreux et leurs spécificités. Ce dernier introduit le formalisme et les concepts nécessaires au traitement des trois problèmes de recherche envisagés. Le Chapitre 2 présente ensuite une étude bibliographique du problème de Horton-Rodgers-Lapwood et des phénomènes de dispersion hydrodynamique en milieux poreux. Le Chapitre 3 est consacré à l’effet Christiansen. Le Chapitre 4 présente les dispositifs de laboratoire mis au point, ainsi qu’une compilation des résultats expérimentaux obtenus. Les problèmes d’écoulements capillaires sont exposés au Chapitre 5, étant donné que la technique expérimentale est différente de celle basée sur l’effet Christiansen. Ce Chapitre compare le nouveau modèle mathématique aux résultats des expériences menées en microgravité durant de nombreuses campagnes de vols paraboliques. Le Chapitre 6 referme ce travail par ses conclusions et perspectives.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
Leroy, Christophe. « Etude experimentale de la dispersion d'un traceur dans des milieux stratifies ou fortement inhomogenes ». Paris 6, 1987. http://www.theses.fr/1987PA066491.
Texte intégralVohralik, Martin. « Méthodes numériques pour des équations elliptiques et paraboliques non linéaires. Application à des problèmes d'écoulement en milieux poreux et fracturés ». Phd thesis, Université Paris Sud - Paris XI, 2004. http://tel.archives-ouvertes.fr/tel-00008451.
Texte intégralSin, Irina. « Modélisation numérique d’écoulement diphasique compressible et transport réactif en milieux poreux - Applications à l'étude de stockage de CO2 et de réservoir de gaz naturel ». Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0058/document.
Texte intégralHuman activity in the subsurface has rapidly been expanding and diversifying (waste disposal, new mining technologies, high-frequency storage of energy), while the public and regulatory expectations keep growing. The assessment of each step of underground operations requires careful safety and environmental impact evaluations. They rely on elaborate simulators and multiphysics modeling. With its process-based approach, reactive transport simulation provides an effective way to understand and predict the behavior of such complex systems at different time and spatial scale.This work aims at incorporating a compressible multiphase flow into conventional reactive transport framework by an operator splitting approach. A multiphase flow module is developed in the HYTEC reactive transport software. A new approach is then developed to fully couple multiphase multicomponent compressible flow, the complex thermodynamic description of the fluid properties, with existing reactive transport codes. The method is implemented in HYTEC. Some validation is provided, before application to the simulation of underground storage of CO2 and associated impurities
Sin, Irina. « Modélisation numérique d’écoulement diphasique compressible et transport réactif en milieux poreux - Applications à l'étude de stockage de CO2 et de réservoir de gaz naturel ». Electronic Thesis or Diss., Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0058.
Texte intégralHuman activity in the subsurface has rapidly been expanding and diversifying (waste disposal, new mining technologies, high-frequency storage of energy), while the public and regulatory expectations keep growing. The assessment of each step of underground operations requires careful safety and environmental impact evaluations. They rely on elaborate simulators and multiphysics modeling. With its process-based approach, reactive transport simulation provides an effective way to understand and predict the behavior of such complex systems at different time and spatial scale.This work aims at incorporating a compressible multiphase flow into conventional reactive transport framework by an operator splitting approach. A multiphase flow module is developed in the HYTEC reactive transport software. A new approach is then developed to fully couple multiphase multicomponent compressible flow, the complex thermodynamic description of the fluid properties, with existing reactive transport codes. The method is implemented in HYTEC. Some validation is provided, before application to the simulation of underground storage of CO2 and associated impurities
Ajalloueian, Mohammad. « Modélisation du transfert des contaminants dans un aquifère multicouche par une méthode de marche au hasard ». Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL013N.
Texte intégralLavie, Guillaume. « Simulation et analyse numérique de procédés de récupération de pétrole caractérisés par des fronts raides ». Thesis, Pau, 2011. http://www.theses.fr/2011PAUU3028/document.
Texte intégralWith rarefaction of conventional petroleum fields and the world supply increase, petroleum companies have to consider new unexploited reserves because of their exploitation cost few years ago. These reserves are called unconventional reserves, mainly heavy oil or extra heavy oil. This work is devoted to the numerical simulation of an extraction process of heavy oil, the VAPEX. VAPEX is characterized by solvent injection in a horizontal well in order to facilitate gravity drainage of oil in a producer well situated in the same way under the injector well. The main stake to simulate this process is to simulate the mechanism of solvent penetration in oil with precision, this penetration zone being very thin drawn to the reservoir scale. We focus our work on application of algorithm of adaptive mesh refinement to simulate this process. This consideration lead us to consider the issue of application of mesh refinement in porous media, especially in heterogeneous porous media for which existing indicators (or estimators) do not allow to determine properly the zone to be refined. The objective of this work is to determine a posteriori estimators for implementation of simulation codes of heterogeneous petroleum reservoirs and their application to the VAPEX process. Firstly, we set the whole equations we have to solve numerically to build simulators of petroleum extraction processes by water injection and solvent injection. Then, we describe the VAPEX process and we establish the semi-analytical study of Butler & Mokrys of this process for which we take in account influence of capillarity. Afterwards, we describe two mathematical methods to establish a posteriori estimators for such problems. One of these methods is based on empirical extrapolation of existing estimators for hyperbolic problems given by Ohlberger. In the course of this work, we set two simulation codes of petroleum reservoirs, the first is a simulator based on equations discretisation by mixed finite element method allowing simulation of water injection problems and the second is based on discretisation by finite volumes method allowing simulation of solvent injection processes like the VAPEX. Then, we apply these estimators to an algorithm of mesh refinement for these two simulation codes. The study of the semi-analytical model set of the VAPEX process show that under hypothesis, capillarity can be likened to a diffusive term to determine the front tracking. Estimators set are based on flux variation and allow determining sharp zone to be refined in heterogeneous porous media. We illustrate this result for a simulation of water injection with the simulator built. The estimators set can also track saturations fronts and concentrations fronts. We illustrate this result on a simulation of the VAPEX process. This work shows it is possible to set estimators allowing mesh refinement to track saturations and concentrations fronts during simulation of flow in heterogeneous porous media. To set such estimators, we make a distinction between saturation (resp. concentration) front and high saturation (resp. concentration) gradient. To our point of view, a front is a high variation of saturation or concentration that has a high impact on the flux variation. It is different from a high gradient that appear automatically where the permeability of the porous media has a high variation. This work could be complemented by making more simulations with variations of capillarity and dispersive terms in order to have a better appreciation of estimators introduced. It would be advisable to study the impact of suppositions done to establish these empirical estimators set. After all, such estimators could be applied to a simulation code taking in account dispersion in porous media
Swaidan, Ali. « Study of water injection with evaporation in a heterogeneous highly degraded nuclear reactor core ». Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0002/document.
Texte intégralSevere accidents arising from the fusion of a nuclear reactor core must be anticipated to enhance the efficiency of their mitigation. Such accidents have occurred at TMI-2 (1979) and Fukushima (2011). Following a loss of coolant accident, core heating and oxidation of the fuel cladding followed by reflooding (injection of water) may lead to the collapse of fuel rods and formation of porous debris bed in the core. Steam produced upon reflooding may activate the exothermic oxidation of Zircaloy leading to partial melting of materials. Such evolution generates zones with reduced porosity limiting coolant penetration and/or impermeable blocked zones. In this situation, the efficiency of injecting water into the core to stop the progress of degradation and prevent the reactor core melting may be significantly reduced. In this scope, IRSN launched PEARL program to investigate the thermal hydraulics of reflooding of hot debris beds surrounded by a more permeable zone simulating the presence of intact or less damaged zones in the core. The PEARL experiments were modeled and simulated using ICARE/CATHARE code to assess the evolution of a bottom reflooding of a superheated debris bed surrounded by a bypass of larger permeability. The thermal hydraulics of the quenching process has been analyzed and the effect of each of the initial conditions on the reflooding behavior was assessed. The effect of pressure was investigated and related to the entrainment of injected water at quench front level into the bypass. An analytical model was then developed to investigate thoroughly the reflooding of a superheated heterogeneous porous medium, composed of two layers of contrasting permeability and porosity, and to describe the water entrainment in the bypass. This model computes the main variables characterizing the reflooding process such as quench front velocity, water-to-steam conversion ratio, and the flow rate of water entrained in the bypass. It provides good qualitative and quantitative results for the two-phase flow redistribution as compared to experimental results. This model has several advantages. It is written in a rather general form including the Forchheimer correction terms and non-zero cross-terms in the generalized Darcy-Forchheimer momentum equation. Variations of proposed momentum equations including changes in correlations andinterfacial friction laws can be tested easily and efficiently. Comparison of the calculations against experimental results indicated that it is necessary to include an interfacial friction law to obtain good predictions. This model allows performing fast evaluations of the efficiency of cooling bycomputing the fraction of the injected flow rate that participates in cooling. Upscaling to the reactor scale is straightforward and calculations were performed to assess the impact of geometric parameters of the debris bed (particle size, porosity, dimensions) as well as thermal hydraulic conditions (temperature, pressure, injection flow rate) on the reflooding process. Thus the model is very useful to estimate the total quenching time and the maximum temperature that could be reached by the hot debris bed at large scales. This allows assessing the probability of a successful quenching of a hot debris bed formed during a hypothetical accidental scenario
Saada, Zied. « Etude expérimentale et théorique de l'injection d'une suspension dans un milieu granulaire : Application aux coulis de ciment ». Phd thesis, Ecole des Ponts ParisTech, 2003. http://pastel.archives-ouvertes.fr/pastel-00000823.
Texte intégralBAUGET, FABRICE. « PRODUCTION D'HUILES LOURDES PAR DÉPRESSURISATION : ÉTUDE DES INTERFACES HUILE-AIR ET MODÉLISATION DU PROCÉDÉ ». Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00006787.
Texte intégralBailly, David. « Vers une modélisation des écoulements dans les massifs très fissurés de type karst : étude morphologique, hydraulique et changement d'échelle ». Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT027H/document.
Texte intégralKarstic 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
Sciumè, Giuseppe. « Thermo-hygro-chemo-mechanical model of concrete at early ages and its extension to tumor growth numerical analysis ». Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3426302.
Texte intégralL’obiettivo del Dottorato è stato lo sviluppo di due modelli multifase basati su fondamenti teorici comuni ma applicati a due campi della ricerca scientifica molto diversi: i) lo studio del comportamento termo-igro-chemo-meccanico del calcestruzzo giovane; ii) l’analisi dei fenomeni fisici, chimici e biologici che regolano la crescita e lo sviluppo dei tumori. La modellazione numerica del comportamento del calcestruzzo giovane è di grande importanza per la progettazione di strutture sostenibili e durevoli. Il modello sviluppato durante il Dottorato è stato implementato nel codice agli elementi finiti Cast3M e in seguito validato con la simulazione di casi sperimentali. Il modello numerico consente un’ampia gamma di applicazioni: studio delle sollecitazioni e dei fenomeni di fessurazione nel calcestruzzo durante i primi giorni dopo la posa in opera, analisi dei gradienti termici e igrometrici, valutazione del ritiro autogeno e di essiccazione, studio dell’inibizione dell’idratazione causata dall’essiccazione, ridistribuzione delle tensioni dovuta al ritiro e alle deformazioni differite, modellazione delle riparazioni. Le equazioni che governano il comportamento termo-igro-chemo-meccanico del calcestruzzo hanno molte analogie formali con quelle che sono tipicamente alla base della modellazione della crescita dei tumori. L'allargamento dell'analisi numerica al campo medico è di grande interesse sociale oltre che scientifico, pertanto le equazioni utilizzate per il calcestruzzo sono state riadattate per la modellazione della crescita tumorale, e il modello matematico ottenuto è stato anch’esso introdotto in Cast3M. I primi risultati di questo modello sono stati soddisfacenti perché qualitativamente molto simili ai dati sperimentali della letteratura scientifica.
Id, Moulay Mohamed. « Simulation numérique 3D d'Écoulement Multiphysiques Réactifs en Milieux Poreux ». Thesis, 2019. http://www.theses.fr/2019PAUU3015.
Texte intégralReactive transport modeling is used in many energy and environmental applications related to subsurface flows. Modeling such problems leads to a highly nonlinear system of PDEs coupled with algebraic or ODEs. Two types of approaches for the numerical solving of reactive transport problems are widely used in the literature. One is the operator-splitting approach which consists in splitting the flow and reactive transport problems. These latter are solved sequentially at each time step. The other strategy is based on the fully coupled approach in which the entire system is solved simultaneously. The goal of the PhD thesis is the development of a fully coupled fully implicit finite volume scheme for numerical modeling of single and two-phase multicomponent flows with reactive transport in porous media. New reactive transport modules will be implemented in DuMuX, a free and open-source simulator for flow and transport processes in porous media. Numerical simulations for 2D and 3D including benchmark tests and high performance computing will be performed to validate the modules