Parmi les méthodes de Récupération Améliorée du Pétrole (RAP) il en existe une, dite chimique, qui fait appel à des fluides complexes (polymères, gels, tensioactifs) qui permet de modifier la viscosité et/ou la tension interfaciale Les solutions de polymères utilisées actuellement présentent l’inconvénient d’être sensibles de manière irréversible aux taux de cisaillement élevés observés au voisinage des puits. Une alternative à ces solutions de polymères pourrait nous être donnée par l’utilisation de micelles géantes. Il s’agit d’auto-assemblages de molécules amphiphiles dont le comportement est similaire à celui des polymères avec l’avantage d’une meilleure stabilité aux cisaillements élevés (capacité des micelles à se reformer après cisaillement).L’objectif de ce travail est d’étudier l’écoulement d’une solution de micelles géantes en milieu poreux, dans le but de déterminer son éventuelle utilité dans le RAP. Il s’agit d’une caractérisation en milieu poreux à l’échelle du laboratoire, utilisant des milieux poreux naturels, de façon à se placer dans un cadre d’étude le plus réaliste possible. Cette étude se divise en trois parties :- Une étude rhéologique de la solution de micelles géantes- Une étude monophasique de l’injection de la solution dans un milieu poreux naturel- Une étude diphasique du déplacement d’huile par la solution de micelles.Les résultats de cette étude seront comparés avec des expériences références utilisant des techniques classiques de récupération telles que l’ASP et l’injection de polymères / Among 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.

Pour effectuer des simulations d'écoulement diphasique dans les réservoirs fracturés, l'usage des modèles DFM entraîne des temps de calculs exorbitants. L'une des solutions envisageables est le recours aux modèles double milieu. Ces modèles nécessitent la détermination des dimensions du bloc équivalent et la mise à l'échelle des paramètres d'écoulement monophasique et diphasique. Concernant les paramètres d'écoulement monophasique, des méthodes de mise à l'échelle existantes ont déjà fait leur preuve. En contrepartie la mise à l'échelle des paramètres d'écoulement diphasique reste un sujet ouvert nécessitant l'identification de la nature des forces (capillaires, gravitaires ou visqueuses) contrôlant l'écoulement dans le réservoir. Dans le cadre de cette thèse, les formulations mathématiques et les modèles numériques liées à la simulation de type DFM et double milieu ont été explorés. Une étude bibliographique portant sur les méthodes existantes de mise à l'échelle a été développée. Une nouvelle méthode de détermination des dimensions du bloc équivalent (méthode OBS) a été mise en place. Une analyse dimensionnelle servant à identifier la nature des échanges matrice-fractures (capillaire ou visqueuses) lors d'un écoulement diphasique eau-huile, sans gravité, a été mise en place. Le nombre capillaire dérivé a été testé. Enfin, une méthodologie de mise l'échelle des paramètres équivalents double milieu a été mise en place. Cette méthodologie traite le cas d'un écoulement diphasique dans les réservoirs fracturés ayant un milieu matriciel hétérogène dans un contexte d'échanges matrice-fractures dominés par les effets visqueux. / In order to carry-out two phase flow simulations within naturally fractured reservoirs, using DFM models results in huge computational costs. Using dual medium models is one of the available alternative solutions. These models require identifying the equivalent bloc dimensions and upscaling single phase and two phase flow parameters. Available upcaling methods related to single phase parameters reached maturity. Otherwise, upscaling two phase flow parameters is still an open research topic requiring identifying the type of the forces controlling flow in the fractured reservoir (gravity, capillary forces, and viscous forces). During this PhD work, mathematical and numerical models related to DFM and dual medium simulations were explored. A study of the state of the art related to upscaling methods was done. A new and original method allowing determining the dual medium equivalent bloc dimensions (OBS method) was settled down. A dimensional analysis aiming at identifying the type of the forces controlling matrix-fracture exchanges (capillarity, viscous forces) in a water-oil two phase flow within naturally fractured reservoirs without gravity was settled down. The derived capillary number was tested. Finally, an equivalent two phase flow parameters upscaling workflow was also settled down. This workflow treats the particular case of a two phase flow in naturally fractured reservoirs with an heterogeneous matrix medium in a context of matrix-fracture exchanges ruled by viscous forces.

Gas-liquid annular two phase flow in pipes is important in the oil and gas, nuclear and the process industries. It has been identified as one of the most frequently encountered flow regimes and many models (empirical and theoretical) for the film flow and droplet behaviour for example have been developed since the 1950s. However, the behaviour in large pipes (those with diameter greater than 100 mm) has not been fully explored. As a result, the two- phase flow characteristics, data, and models specifically for such pipes are scarce or non-existent such that those from smaller pipes are extrapolated for use in design and operation. Many authors have cautioned against this approach since multiphase pipe flow behaviour is different between small and large pipes. For instance the typical slug flows seem not to occur in vertical upwards flows when the pipe diameter exceeds 100 mm. It is therefore imperative that theoretical models and empirical correlations for such large diameter pipes are specifically developed.

The geological repository for final storage of spent nuclear fuel, envisioned by the Swedish Nuclear Fuel and Management Company (SKB), relies on several barriers: copper canisters deposited in holes in the floor of underground tunnels in deep bedrock, embedded in a buffer of compacted bentonite. The initially unsaturated buffer would take up water from the surrounding rock mass and swell to seal any potential gap. This initial two-phase (gas and liquid) regime with two components (air and water) may impact the final density, swelling pressure and biogeochemical conditions in the buffer. A main objective of this work is to identify factors and mechanisms that govern deposition hole inflow and bentonite wetting under the prevailing two-phase flow conditions in sparsely fractured bedrock. For this purpose, we use the numerical code TOUGH2 to perform two-phase flow simulations, conditioned by a companion field experiment (the Bentonite Rock Interaction Experiment or BRIE) performed in a 417 m deep tunnel of the Äspö Hard Rock Laboratory in southeastern Sweden. The models predict a significant de-saturation of the rock wall, which was confirmed by field data. To predict the early buffer wetting rates and patterns, the position of local flowing fractures and estimates of local rock matrix permeability appear more important than the total open hole groundwater inflow. A global sensitivity analysis showed that the buffer wetting time and the persistence of unsaturated conditions over extended periods of time in the rock depend primarily on the local fracture positions, rock matrix permeability, ventilation conditions in the tunnel and pressure far in the rock. Dismantling photographs from BRIE were used to reconstruct a fine-scale snapshot of saturation at the bentonite/rock interface, showing tremendous spatial variability. The high level of heterogeneity in the rock generates complex two-phase flow phenomena (air trapping, dissolution), which need to be accounted for in buffer design and rock suitability criteria. In particular, results suggest that uncertainties regarding two-phase flow behavior are relatively high close to residual air saturation, which may also have important implications for other applications involving two-phase flows, such as geological storage of carbon dioxide. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 4: Manuscript.</p>

Lorsqu'un verre libère trop rapidement le gaz qu'il contient, la disparition des arômes véhiculés par la bulle est soudaine et irrémédiable. Ainsi, la connaissance des mécanismes physiques à l'origine de la libération du CO2 dans un verre de champagne doit permettre de mener à une forme de verre propice à un épanouissement des arômes et à une effervescence durable. La contribution des processus convectifs de brassage du vin sur la désorption du CO2 demeure assez mal connue. Pour approfondir notre compréhension de ces aspects, nous analysons les processus de libération du dioxyde de carbone au cours d'une dégustation. La démarche adoptée dans cette thèse consiste à étudier les mécanismes de transferts de masse (nucléation, diffusion, évaporation) entre les phases liquide et gazeuse. Par le biais de méthodes expérimentales (tomographie laser, PIV, thermographie IR) et numérique (code CFD), nous réalisons le suivi de l'évolution instationnaire de l'écoulement diphasique dans un verre de champagne. Nous mettons en évidence un écoulement complexe, composé de multiples instabilités hydrodynamiques. Les résultats montrent également que la libération du CO2 dépend intimement de la forme du verre et de la température de service du vin. En mettant en évidence le rôle de la forme du verre sur la libération du CO2, ces travaux ont permis d'améliorer la connaissance des paramètres qui affectent ou favorisent l'effervescence au cours d'une dégustation. Ces conclusions devront être confirmées par un panel de dégustation pour montrer que la libération des arômes est étroitement liée à la forme du verre qui reçoit le vin. / When a glass releases too quickly his dissolved gas, the loss of the aromas carried by the bubbles is sudden and irreversible. So, the knowledge of the physical mechanisms at the origin of CO2 release in a glass of champagne should lead to a glass shape conducive to aromas development and at a sustainable effervescence.The contribution of mechanisms of admixture of the wine on the CO2 desorption in a glass of champagne remains still unknown. To deepen our understanding of these aspects, we analyze the carbon dioxide release processes in tasting conditions. The approach adopted in this thesis consists in studying the mass transfer mechanisms (nucleation, diffusion, evaporation) between the liquid and gaseous phase. By experimental (laser tomography, PIV, IR thermography) and numerical ways (CFD), we follow the unsteady evolution of the two phase flow in a champagne glass. We highlight a complex flow, composed of multiple hydrodynamic instabilities. The results show also that the CO2 release strongly depends on the glass shape and on the wine temperature.By highlighting the glass shape on the carbon dioxide release, these works allowed to improve the parameters knowledge which affect or favor the effervescence process in tasting conditions. These conclusions must be confirmed by a tasting panel to show that the aromas release is closely related to the glass shape.

<div>As space exploration continues to accelerate, various cooling applications follow suit. Refrigeration and freezing of biological samples, astronaut food as well as electronics cooling and air-conditioning are necessary and demand increased capacity. In the past, these demands have been met by thermoelectric cooling or cryogenic cycles, which are easily adapted to a microgravity environment but have a relatively low efficiency in the refrigeration and freezing temperature range. A number of studies have investigated the development of higher efficiency vapor compression cycles for spacecraft, which would have the benefit of a smaller mass penalty due to the reduced power consumption. Despite notable research efforts during the 1990s, the number of vapor compression coolers that have operated in microgravity until today is small and their performance was insufficient to provide confidence into the technology for microgravity applications. Related experimental research has decreased since the 2000s.<br></div><div><br></div><div>For this dissertation, all vapor compression cycles (VCC) that have operated in microgravity according to the open literature were reviewed with their applications, compressor types and reported issues. Suggested design tools were summarized with a focus on gravity independence criteria for two-phase flow. For the most effective increase of the technology readiness level, simple but systematic experiments regarding the stability of VCCs against orientation and gravity changes were prioritized in this dissertation. An important goal of the research was the continuous operation and start-up of vapor compression cycles on parabolic flights, experiments that have not been reported in the open literature. Two separate test stands were built and flown on four parabolic flights, totaling 122 parabolas for each experiment.<br></div><div><br></div><div>The parabolic flight experiments were prepared with extensive ground-based testing. Multiple anomalies were encountered during the pursuit of continuous vapor compression cycle operation through a rotation of 360 degrees, including liquid flooding of the compressor. Systematic inclination testing was conducted with two different cycle configurations and a wide range of operating conditions. A strong correlation was found between the relative stability of the heat source heat transfer rate and the refrigerant mass flux for an inclination procedure with angle changes once every 2 minutes.<br></div><div><br></div><div>The parabolic flights exposed the test stand to quickly alternating hyper and microgravity. The evaporation temperature reacted to the different gravity levels with fluctuations that stretched on average 2.2 K from the maximum to minimum temperature measured during one set of parabolas. Changes of the evaporator inlet flow regime as a function of gravity were observed visually and the low-side pressure and mass flow rate sometimes oscillated in microgravity. The cycle responses induced by ground-based inclination testing were typically stronger than changes caused by the parabolic flight maneuvers for relatively low mass flow rates. Overall, the parabolic flight maneuvers were not detrimental to the cycle operation. <br></div><div><br></div><div>The second test stand was dedicated to liquid flooding observations at cycle start-up. Different flow regimes were observed in microgravity during testing with a transparent evaporator but the absence of gravity did not significantly alter the general time-based flooding quantifiers.<br></div><div><br></div><div>Design recommendations are drawn from the research where possible and summarized at the end of the dissertation. Selected data, code, pictures and videos were released together with this dissertation(Brendel, 2021)<br></div>

The master´s thesis focuses on the behavior of the siphon turbine during unsteady flow. There are two possible conditions. The first condition involves commissioning the turbine. In this situation turbine works like a pump. In the second case, it includes shutting down the turbine by aerating the siphon and thereby breaking the water column. This thesis deals with the second case, where the results of the experiment and the mathematical model are compared.

Graduation these deals with investigation of critical heat flux in pressurized water nuclear reactors. Theoretical part covers fundamental terms from area hydrodynamics of two-phase flow and critical heat flux. Here are also mentioned the individual approaches to description of physical process of heat transfer crisis. Practical part is devoted to systems design of measuring stand for critical heat flux in vertical canal allowing visualization of two-phase flow.

Doctoral thesis deals with the numerical simulations of two-phase flows, especially with prediction of movement of dispersed phase (particles) carried by fluid. The Euler-Lagrange approach was applied for description of the system fluid-particles. It means that the fluid is considered to be continuum and its movement is described using Euler approach. Particles are regarded as mass points and their movement is solved using Lagrangian approach. The Large Eddy Simulation method was adopted for solution of the fluid flow. The series of simulations of the backward-facing step flow laden with particles were performed. The concentration of the particles in the flow was high enough for consideration of the influence of particles on the turbulence of the carrier phase. The developed scheme for generation of turbulence on the inlet is applied. The influence of anisotropic decomposition of subgrid energy on movement of particles was studied in the frame of this work.

Le CEA aspire à la création d'un réacteur nucléaire numérique qui nécessite une grande connaissance des écoulements diphasiques. Dans le but d'améliorer notre compréhension des scénarios accidentels, cette thèse s’attache à étudier et à modéliser la dynamique complexe des écoulements à bulles. Les principaux enjeux de la thèse sont d’étudier et de modéliser les forces interfaciales responsables de la migration des bulles ainsi que de proposer un modèle de turbulence à la hauteur de la connaissance actuelle des phénomènes. Afin d'atteindre ces objectifs, une base de données statistique est réalisée à partir d'expériences numériques (simulations numériques directes) d'essaims et de canaux à bulles. Une nouvelle méthode de modélisation des forces interfaciales est développée. Elle révèle une nouvelle force baptisée force de dispersion laminaire qui a un rôle important dans la migration des bulles. Un modèle de cette force est donc proposé. La turbulence dans les écoulements à bulles est constituée de SPT (Single Phase Turbulence), de WIT (Wake Induced Turbulence) et de WIF (Wake Induced Fluctuations). Le SPT est la turbulence issue du cisaillement moyen, le WIT représente les fluctuations temporelles turbulentes issue de la déstabilisation collectives des sillages, et le WIF est fait de fluctuations spatiales engendrées par le sillage moyen. Dans cette thèse, nous proposons une nouvelle forme de modélisation à trois équations de la turbulence, où chaque contribution possède sa propre fermeture. Le modèle à trois équations tensorielles ainsi écrit est complet et peut être dès aujourd'hui utilisé dans un code de calcul moyenné. / The CEA aspires to create a numerical nuclear reactor which requires a great knowledge of two-phase flows. In order to improve our understanding of accidental scenarios, this thesis focuses on studying the complex dynamics of bubbly flows in order to model them. The main challenges of the thesis are to study and model the interfacial forces responsible for the migration of bubbles as well as to propose a model of turbulence in agreement with the current knowledge of the phenomena. In order to achieve these objectives, a statistical database is produced from numerical experiments (direct numerical simulations) of swarms and bubble channels. In this thesis, a new method for interfacial forces modeling is developed. It reveals a new force coined as laminar dispersion force. This force has an important role in bubble migration. It is then modeled and validated on five simulations of bubble channels. Concerning turbulence in bubbly flows, it is comprised of SPT (Single Phase Turbulence), WIT (Wake Induced Turbulence) and WIF (Wake Induced Fluctuations) which characterize distinct phenomena. The SPT is the turbulence produced by the averaged shear, the WIT represent the temporal and turbulent fluctuations due to destabilizations and collective instabilities of wakes, and the WIF reflect the spatial fluctuations generated by the averaged wake and the potential flow around the bubbles. In this thesis, we propose a tensorial three-equations modeling of turbulence, where each contribution has its own closure. The tensorial three-equation model is complete and can be assessed as of now in an averaged calculation code.