Die vorliegende Dissertationsschrift beinhaltet die Ergebnisse der Untersuchung von loka-len und globalen Prozessen der Wärmeübertragung beim unterkühlten Strömungssieden. Sie ist an der Schnittstelle zwischen Reaktorsicherheitsforschung und der experimentellen Thermofluiddynamik für Phasenübergänge einzuordnen. In technischen Anwendungen zur effizienten Übertragung großer Wärmemengen spielt der Prozess des Siedens eine wichtige Rolle. Dieser Vorgang bewirkt einen starken Anstieg des Wärmetransportes von der beizten Wand an das Fluid bei vergleichsweise geringem Anstieg der Wandtemperatur. Der maximal übertragbare Wärmestrom beim Sieden wird begrenzt durch die sogenannte kritische Wärmestromdichte, deren Überschreitung zum thermomechanischen Versagen der beheizten Komponente führen kann. Aufgrund der Komplexität dieser Prozesse ist es trotz intensiver Arbeiten in den letzten Jahrzehnten noch nicht gelungen, diese Vorgänge detailliert zu modellieren. Eine Weiter-entwicklung der Modelle zur realistischen Beschreibung des unterkühlten Strömungssie-dens erfordert neuartige Untersuchungen, welche eine genaue Klassifizierung der partiellen Wärmeübergänge des Blasensiedens ermöglichen. Die Analyse partieller Wärmetransportgrößen beim unterkühlten Strömungssieden sowie der Einfluss variierender thermohydraulischer Randbedingungen ist Schwerpunkt dieser Arbeit. In der entwickelten Versuchsanlage erfolgt die Erfassung der Siedevorgänge bei Strömungsgeschwindigkeiten von 0,1 – 2 m/s und Eintrittstemperaturen von 60 - 98 °C. Mit Hilfe empfindlicher Temperaturmessungen in einem elektrisch beheizten Kapillarrohr innerhalb des Strömungskanals werden die globalen Vorgänge beim Übergang von Kon-vektion zum Sieden erfasst. Durch eine modellbasierte Bestimmung der Oberflächentem-peratur lassen sich Phänomene nachweisen, welche bisher weitestgehend unbeachtet ge-blieben sind. Die transparente Versuchsstrecke ermöglicht eine Erfassung der lokalen Sie-devorgänge mit optisch und zeitlich hochauflösenden Messverfahren. Durch die Entwick-lung neuer Algorithmen der digitalen Bildverarbeitung wurde eine umfangreiche, kenngrö-ßenorientierte Auswertung der in großem Umfang entstandenen Datenmengen realisiert. Der Einsatz transparenter und elektrisch leitfähiger Beschichtungen ermöglicht die mikro-skopische Erfassung des Blasenwachstums in weiten thermohydraulischen Parameterberei-chen. Mit erweiterten Bildverarbeitungsalgorithmen erfolgt die detaillierte und dynamische Bewertung des Blasenwachstumsverhaltens. Die statistische Auswertung der Verläufe er-möglicht die Ableitung eines Blasenwachstumsmodells für unterkühltes Strömungssieden. In einer weiteren Versuchsanordnung werden die lokalen Wärmetransportvorgänge bei der Ablösung quasistatisch gewachsener Blasen mit Hilfe der Infrarot-Thermographie be-stimmt. Dadurch können erstmalig die aus der lokalen Abkühlung der beheizten Oberfläche durch Blasenablösung resultierenden Wärmeströme unter Vernachlässigung der Bla-senbildung experimentell quantifiziert werden. Weiterhin können die bisher theoretisch beschriebenen Driftströmungen beim Aufstieg der Blase experimentell nachgewiesen wer-den. Die ermittelten Größen und Zusammenhänge tragen zur Weiterentwicklung und zum Abbau von Unsicherheiten bei der Modellierung von Wärmetransportvorgängen beim unterkühlten Strömungssieden bei.

Dans le secteur aéronautique, la performance des alliages d’aluminium connait une amélioration continue, grâce notamment à l’optimisation des procédés d’élaboration. Dans ce cadre, le travail de recherche vise à prédire le comportement des inclusions dans un bain d’aluminium brassé par induction afin d’améliorer la propreté inclusionnaire des alliages coulés. Un modèle numérique a été développé pour simuler le comportement magnétohydrodynamique du bain d’aluminium dans le creuset suivi par la modélisation du comportement d’une population d’inclusions non-métalliques. Le modèle 2D axisymétrique en régime transitoire s’appuie sur le code de CFD commercial ANSYS Fluent, bien que de nombreuses fonctions utilisateurs aient été introduites pour simuler les phénomènes spécifiques comme l’induction électromagnétique et la résolution des bilans de population. Le modèle MHD résout dans un unique maillage les phénomènes d’induction électromagnétiques, l’écoulement turbulent du bain d’Al, la déformation de la surface libre et les effets de la présence d’une couche de métal oxydée en surface du bain. Une méthode dite de vitesse de glissement (entre les particules et le fluide) a été choisie pour simuler à la fois le transport macroscopique des inclusions dans le bain d’Al et les interactions mésoscopique entre les inclusions (c.à.d. les mécanismes d’agrégation et de fragmentation). Des campagnes expérimentales à l’échelle d’un four de laboratoire et d’une installation industrielle accompagnent le travail numérique pour le valider. Les résultats de modélisation MHD exprimés sous la forme du profil de déformation du bain sont en accord raisonnable avec les mesures faites au laboratoire. Les résultats numériques démontrent également l'effet du frottement induit par la couche d'oxyde sur le profil du bain, ainsi que sur l'écoulement à proximité de la surface du dôme. Pour des conditions opératoires du four industriel en mode de maintien, l’évolution temporelle de la population au sein du bain est calculée. Il apparaît que la séparation magnétique est très intense, particulièrement dans la peau électromagnétique, et est ainsi responsable du transport et de la capture d’une grande fraction de la population d’inclusions à la paroi du four. / With an objective of improving processing and development of aerospace aluminum alloys, the current dissertation presents experimental and numerical tools which help comprehend the behavior of a non-metallic inclusion population in an Al bath stirred by induction. The mechanisms occurring in the metallurgical reactor were separated into two interlinked issues – (i) Magnetohydrodynamics (MHD) of the induction furnace, and (ii) Inclusion population dynamics in the Al bath, which were modeled using the ANSYS Fluent software and in-house User Defined Functions. For a 2D axisymmetric geometry, numerical simulations were performed in a single framework and calculated: (i) the electromagnetic forces using the A-V formulation, (ii) the free surface deformation using the Volume Of Fluid method, (iii) the turbulent stirring of the bath using a RANS-based k-omega model and (iv) the friction force due to the oxide layer by imposing a pseudo-wall condition on the bath free surface. The steady state MHD results and the physical properties of the inclusion population were used as input data for the transient inclusion behavior modeling. A combination of the Drift Concentration Method and the Population Balance Method was developed to respectively model the mean transport of inclusions within the bath at the macroscopic scale and the inclusion interactions (turbulent aggregation and fragmentation) at the mesoscopic scale. The performance of the MHD numerical tool was evaluated by comparing the model results with experimental results at laboratory and industrial scales. The simulation results in the form of the average bath surface profile were found to be consistent with the laboratory measurements. The results also illustrated the impact of the friction due to the oxide layer on the bath surface deformation as well as on the flow near the dome interface. The inclusion behavior simulations were performed for the holding mode operation of an industrial IMF. The deduced removal frequency compared the relative importance of each phenomenon. It was found that the electromagnetic migration, especially in the electromagnetic skin, dominates the inclusion dynamics and is responsible for the capture of a large fraction of the inclusion population.

The main purpose of this thesis was to propose and test a new approach that captures the features of single and multiple bubbles dynamics using the Shan and Chen-type lattice Boltzmann method (LBM). Two dimensional bubbles motions were simulated considering the buoyancy effect for which the topology of the bubble is characterized by the Eötvös (Eo), and Morton (M) numbers. A qualitative and quantitative validation were performed using the Level set method. Bubble shape deformation was captured and analysis based on terminal Reynolds number and degree of circularity show very good agreement with the experimental results and with available simulation results. In sum, this study presents crucial preliminary information to further analyze multiphase fluid flows in various contexts.

Orientadores: Denis José Schiozer, Eliana Luci Ligero / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-26T15:17:18Z (GMT). No. of bitstreams: 1 Santana_GustavoMenezes_M.pdf: 19965408 bytes, checksum: 111a8315e511e6681fab2b5663345c52 (MD5) Previous issue date: 2014 / Resumo: Os reservatórios do pré-sal brasileiro apresentam grandes volumes de óleo leve com quantidade significativa de CO2 dissolvido. O CO2 produzido no pré-sal pode ser utilizado como gás de injeção no método especial de recuperação de injeção alternada de água e gás (WAG). Neste trabalho, a injeção WAG-CO2 miscível é empregada na recuperação de um óleo leve com teor de cerca de 8% molar de CO2 em condições análogas às do pré-sal de alta pressão e baixa temperatura, onde fenômenos físicos inerentes à injeção WAG-CO2 são incorporados aos modelos de simulação de reservatórios através dos modelos de histerese da permeabilidade relativa, tal como o modelo trifásico de Larsen e Skauge (1998). Este trabalho tem como foco o estudo dos efeitos da modelagem da histerese de permeabilidade relativa em simulações de injeção WAG-CO2 miscível. Dois modelos sintéticos de reservatório com óleo leve e com diferentes graus de heterogeneidade são estudados. Os modelos de simulações empregam a formulação composicional por ser mais apropriada em casos de injeção de gás miscível em óleo leve. A histerese causa redução da permeabilidade relativa aos fluidos, o que pode gerar dois efeitos: o aumento da eficiência local de varrido de óleo e a perda de injetividade. O primeiro efeito contribui para o aumento da recuperação de óleo, enquanto a perda de injetividade, dependendo das condições operacionais dos poços, resulta na redução da quantidade de fluidos injetada, prejudicando a recuperação. O predomínio de um desses dois efeitos faz com que a implementação dos efeitos da histerese de permeabilidade relativa nos modelos de simulação com injeção WAG resulte em recuperações finais de óleo diferentes das obtidas nos casos em que a histerese não é considerada, atingindo-se valores até 8% maior ou menor conforme efeito predominante e condições operacionais utilizadas / Abstract: The Brazilian pre-salt reservoirs present large volumes of light oil with a significant amount of dissolved CO2. It is intended to use CO2 produced in the pre-salt as an injection gas on the enhanced oil recovery method of water-alternating-gas (WAG) injection. In this work, the miscible WAG-CO2 injection is used in light oil recovery with an amount of 8% molar CO2 in similar conditions to pre-salt with high pressure e low temperature where physical phenomena involving WAG-CO2 injection applied to a reservoir of light oil with dissolved CO2 are built into the reservoir simulation models through the hysteresis of relative permeability models, as the Larsen and Skauge (1998) model. This work focuses on the study of the effects of modeling the hysteresis of relative permeability in simulation of miscible WAG-CO2 injection. Two synthetic reservoir models with light oil and different heterogeneities are studied. The simulation models employ the compositional formulation because it is more appropriate in cases of miscible gas injection in light oil. The hysteresis causes a reduction of the relative permeability of the fluid, which can cause two effects: increased local oil swept efficiency and the loss of injectivity. The first effect contributes to increase the oil recovery, while the loss of injectivity, depending on the operating conditions of the wells, results in a reduction of the amount of injected fluids, reducing the recovery. The predominance of one of these two effects makes the implementation of the effects of hysteresis of the relative permeability in simulation models with WAG injection exhibit different results compared to those models without hysteresis, reaching values up to 8% higher or lower according to the predominant effect and operational conditions used / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

Orientadores: Antonio Carlos Bannwart, Oscar Mauricio Hernandez Rodriguez / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-28T09:34:02Z (GMT). No. of bitstreams: 1 BonillaRiano_Adriana_D.pdf: 7155927 bytes, checksum: 63be57b0a5136f5e783cfb4f870b0189 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho, é apresentado o desenvolvimento de uma nova técnica para a medição da espessura do filme de água com alta resolução espacial e temporal em escoamento óleo-água. É proposto o uso de um sistema de medição de capacitância elétrica para medir filmes finos de água na proximidade da parede do tubo. O sistema conta com um sensor planar e foi necessário determinar a melhor geometria via simulações baseadas no Método de Elementos Finitos (FEM) para o caso de escoamento óleo-água. As características comparadas foram a profundidade de penetração do campo elétrico no filme de água, a sensibilidade, a resolução espacial mínima e a resposta quase-linear. Padrões de escoamento óleo-água disperso e anular instável foram estudados numa tubulação vertical de 12 m de comprimento, feita de vidro, com 50,8 milímetros de diâmetro interno. Os fluidos usados foram óleo mineral (com densidade 828 kg/m3 e viscosidade 220 mPas) e água da torneira. O trabalho experimental foi realizado nas instalações de escoamento multifásico do Laboratório de Engenharia Térmica e Fluidos (NETeF) da EESC-USP. Foi medida a espessura média do filme de água usando o sistema capacitivo e uma câmera de vídeo de alta velocidade. Para obter a espessura do filme de água a partir das imagens, foi proposto um algoritmo de pré-processamento e um algoritmo de segmentação que combina vários métodos disponíveis na literatura. Os resultados experimentais do sensor capacitivo mostraram que o sistema pode medir espessuras entre 400 µm e 2200 µm. O escoamento anular instável é caracterizado por grandes flutuações na no sentido do escoamento e na direção do perímetro, e estruturas interfaciais grandes (gotas). Por sua vez, o escoamento disperso tem flutuações menores no sentido do escoamento e na direção do perímetro, e estruturas interfaciais menores (gotículas). Uma estrutura interfacial média no espaço e no tempo é proposta para modelar a interface entre a região próxima à parede do tubo e a região do núcleo, e sua análise foi feita no domínio do tempo e da frequência. Foram estudadas a amplitude, velocidade e o comprimento da estrutura interfacial em cada par transmissor-receptor do sensor. Foi possível estabelecer correlações para a velocidade das estruturas em escoamento de óleo em água / Abstract: The development of a new technique for high spatial and temporal resolution film thickness measurement in oil-water flow is presented. A capacitance measurement system is proposed to measure thin water films near to the wall pipe. A planar sensor was chosen for sensing and some geometries were compared using finite elements method (FEM). The penetration depth, the sensitivity, the minimum spatial resolution (high spatial resolution) and the quasi-linear curve were the analyzed characteristics. Dispersed and unstable-annular oil-water flows patterns were studied in a 12-m long vertical glass pipe, with 50.8 mm of internal diameter, using mineral oil (828 kg/m3 of density and 220 mPa s of viscosity) and tap water. The experimental work was carried out in the multiphase-flow facilities of The Thermal-Fluids Engineering Laboratory (NETeF) of EESC-USP. Experiments with a high-speed video camera and the proposed capacitance system were performed to obtain images of the oil-water flow near the pipe wall. A pre-processing enhancement algorithm and a combined segmentation algorithm are proposed and allowed the measurement of characteristic space and time averaged water film thickness. Experimental results of the capacitive technique showed that the system could measure thickness between 400 µm and 2200 µm. It was possible to recognize and characterize typical behaviors of the two different flow patterns studied. Unstable-annular flow can be described by huge fluctuations on the flow direction and perimeter direction, and big interfacial structures (drops). On the other hand, dispersed flow has tiny fluctuations on the flow direction and perimeter direction, and smaller interfacial structures (droplets). An interfacial structure is suggested in order to model the interface between wall and core regions and it was analyzed in time and frequency domains; amplitude, velocity and wavelength at each pair transmitter-receiver of the sensor were studied. Correlations for the interfacial structure velocity were found for dispersed oil-in-water flow and unstable-annular flow / Doutorado / Explotação / Doutora em Ciências e Engenharia de Petróleo / CAPES

La modélisation du transport réactif est utilisée dans de nombreuses applications énergétiques et environnementales liées aux écoulements souterrains. La modélisation de tels problèmes conduit à un système hautement non linéaire d'EDP couplées à des équations différentielles ordinaires ou algébriques. Deux types d'approches pour la résolution numérique des problèmes de transport réactif sont largement utilisés dans la littérature. L'une est l'approche de séparation des opérateurs qui consiste à découpler les problèmes d'écoulement et de transport réactif. Ces derniers sont résolus séquentiellement à chaque pas de temps. L'autre stratégie est basée sur une approche entièrement couplée dans laquelle le système entier est résolu simultanément. Le but de la thèse de doctorat est le développement d'un schéma implicite en volumes finis pour la modélisation numérique d'écoulements multicomposants monophasiques et diphasiques avec transport réactif en milieu poreux.Deux nouveaux modules de transport réactif seront implémentés dans DuMuX, un simulateur libre pour les problèmes d'écoulements et de transport dans les milieuw poreux. Des simulations numériques bi et tridimensionnels comprenant des benchmarks et du calcul haute performance, seront effectuées pour valider les modules. / Reactive 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.

In this paper we present detailed Euler-Euler Large Eddy Simulations (LES) of dispersed bubbly flow in a rectangular bubble column. The motivation of this study is to investigate potential of this approach for the prediction of bubbly flows, in terms of mean quantities. The set of physical models describing the momentum exchange between the phases was chosen according to previous experiences of the authors. Experimental data, Euler-Lagrange LES and unsteady Euler-Euler Reynolds-Averaged Navier-Stokes model are used for comparison. It was found that the presented modelling combination provides good agreement with experimental data for the mean flow and liquid velocity fluctuations. The energy spectrum made from the resolved velocity from Euler-Euler LES is presented and discussed.

In der vorliegenden Arbeit werden verschiedene Simulationsansätze angewandt um die Hydrodynamik in einem neu entwickelten Wirbelschichtvergaser zu untersuchen. Die Ansätze umfassen a) entdimensionalisierter Ähnlichkeitskennzahlen und empirischer Gleichungen, b) 1D Simulationen mittels ASPEN Plus®, c) 3D CFD Simulationen mittels Ansys Fluent® zur detaillierten Abbildung der zu erwartenden Hydrodynamik. Vor- und Nachteile der jeweiligen Ansätze sowie Klassen von ermittelbaren Simulationsdaten werden diskutiert. Ein Schwerpunkt der Arbeit liegt in der Identifizierung geeigneter Experimente aus der Literatur, auf Basis von Ähnlichkeitskennzahlen, um die Simulationen zu validieren. Die Vergasersimulationen zeigen, dass sich erwartungsgemäß ein aus hydrodynamischer Sicht gestufter Prozess ausbildet. Die entstehenden Zonen lassen sich als Festbett, blasenbildende Wirbelschicht, Jet-Wirbelschicht mit Rezirkulationszelle und strähnenbildende, zirkulierende Wirbelschicht identifizieren und entsprechen demnach dem Verfahrensanspruch.:1 INTRODUCTION 1 1.1 Market Situation 1 1.2 Objective Work 3 1.3 Structure of this Work 4 2 FUNDAMENTAL CONSIDERATIONS 5 2.1 Fundamentals of Gasification and Gasifiers 5 2.1.1 Counter-Current Fixed-Bed Gasifiers 7 2.1.2 Fluidized-Bed Gasifiers 9 2.1.3 Entrained-Flow Gasifiers 10 2.1.4 Technology Development Trends 11 2.1.5 Conclusion 12 2.2 Fundamentals of Fluidized-Bed Systems 13 2.2.1 Particle Characterization 13 2.2.2 Types of Fluidized Beds and Key Parameters 15 2.2.3 Fast-Fluidized Beds 18 2.2.4 Jetting-Fluidized Beds 19 2.2.5 Spouted Beds 24 2.2.6 Conclusion 27 3 APPROACHES TO ASSESS FLUIDIZED BEDS 28 3.1 Empirical Simulation 28 3.1.1 Nondimensional groups 28 3.1.2 Conclusion 36 3.2 Simulation with ASPEN Plus® 36 3.3 CFD Simulation 38 3.3.1 Modelling Approaches for Numerical Simulation of Fluidized Beds 38 3.3.2 Two Fluid Model (TFM) 40 3.3.3 Kinetic Theory of Granular Flow (KTGF) 44 3.3.4 Conclusion 46 4 COORVED GASIFICATION CONCEPT 48 4.1 Concept of Staged Conversion 48 4.1.1 Drawbacks of Conventional Fluidized-Bed Gasifiers 48 4.1.2 Basic Concept COORVED Gasifier 49 4.1.3 COORVED – Fixed-Bed Zone 49 4.1.4 COORVED – Bubbling-Bed Zone 50 4.1.5 COORVED – Jetting-Bed Zone 50 4.1.6 COORVED – Fast-Bed Zone 51 4.1.7 Conclusion 51 4.2 Test Facility and Reactor Design 52 4.3 Cold Flow Test Unit 53 4.4 Reference Cases 54 4.4.1 Solids Characterization 54 4.4.2 Gas Phase Properties 54 5 COORVED REACTOR IN FLOW REGIME DIAGRAMS 56 5.1 Reh Diagram for the Reference Case 56 5.2 Reh Diagram for Experimental Campaigns and CFD Case 57 5.3 Regime Diagrams for the Jetting-Bed Zone 60 5.4 Conclusion 61 6 CFD SIMULATION OF COORVED REACTOR 62 6.1 Verification of Multiphase CFD Setup 62 6.1.1 Parallelization 64 6.1.2 Pressure Drop and Minimum Fluidization Velocity 65 6.1.3 Conclusion 67 6.2 Grid Study 68 6.2.1 Pressure Drop 69 6.2.2 Voidage Profiles 69 6.2.3 Velocity Profiles 71 6.2.4 Conclusion 72 6.3 Validation Experiment Bubbling Bed and Fast Bed 72 6.3.1 Experimental Setup Holland 73 6.3.2 Simulation Setup 75 6.3.3 Results 77 6.3.4 Conclusion 84 6.4 Validation Experiment Jetting Bed 85 6.4.1 Experimental Setup 85 6.4.2 Simulation Setup 87 6.4.3 Results 88 6.4.4 Conclusion 95 6.5 CFD Simulation COORVED 96 6.5.1 Computational Grid 97 6.5.2 Cold Flow, Single Phase Jet 97 6.5.3 CFD setup 99 6.5.4 Results 99 6.5.5 Conclusion 103 7 ASPEN PLUS® SIMULATION OF THE COORVED GASIFIER 105 7.1 Validation Experiment Bubbling Bed and Fast Bed 105 7.2 COORVED Simulation 107 7.3 Conclusion 108 8 SUMMARY 109 9 OUTLOOK 114 9.1 Modeling Tools 114 9.2 COORVED Development 114 10 APPENDIX 115 11 REFERENCES 120

Multiphase flow denotes the simultaneous flow of two or more physically distinct and immiscible substances and it can be widely found in several engineering applications, for instance, power generation, chemical engineering and crude oil extraction and processing. In many of those applications, multiphase flows determine safety and efficiency aspects of processes and plants where they occur. Therefore, the measurement and imaging of multiphase flows has received much attention in recent years, largely driven by a need of many industry branches to accurately quantify, predict and control the flow of multiphase mixtures. Moreover, multiphase flow measurements also form the basis in which models and simulations can be developed and validated. In this work, the use of electrical impedance techniques for multiphase flow measurement has been investigated. Three different impedance sensor systems to quantify and monitor multiphase flows have been developed, implemented and metrologically evaluated. The first one is a complex permittivity needle probe which can detect the phases of a multiphase flow at its probe tip by simultaneous measurement of the electrical conductivity and permittivity at up to 20 kHz repetition rate. Two-dimensional images of the phase distribution in pipe cross section can be obtained by the newly developed capacitance wire-mesh sensor. The sensor is able to discriminate fluids with different relative permittivity (dielectric constant) values in a multiphase flow and achieves frame frequencies of up to 10 000 frames per second. The third sensor introduced in this thesis is a planar array sensor which can be employed to visualize fluid distributions along the surface of objects and near-wall flows. The planar sensor can be mounted onto the wall of pipes or vessels and thus has a minimal influence on the flow. It can be operated by a conductivity-based as well as permittivity-based electronics at imaging speeds of up to 10 000 frames/s. All three sensor modalities have been employed in different flow applications which are discussed in this thesis. The main contribution of this research work to the field of multiphase flow measurement technology is therefore the development, characterization and application of new sensors based on electrical impedance measurement. All sensors present high-speed capability and two of them allow for imaging phase fraction distributions. The sensors are furthermore very robust and can thus easily be employed in a number of multiphase flow applications in research and industry.

Understanding flow and transport in porous media is critical as it plays a central role in many biological, natural, and industrial processes. Such processes are not limited to one length or time scale; they occur over a wide span of scales from micron to Kilometers and microseconds to years. While field-scale simulation relies on a continuum description of the flow and transport, one must take into account transport processes occurring on much smaller scales. In doing so, pore-scale modeling is a powerful tool for shedding light on processes at small length and time scales.<br><br>In this work, we look into the multi-phase flow and transport through porous media at two different scales, namely pore- and Darcy scales. First, using direct numerical simulations, we study pore-scale Eulerian and Lagrangian statistics. We study the evolution of Lagrangian velocities for uniform injection of particles and numerically verify their relationship with the Eulerian velocity field. We show that for three porous media velocity, probability distributions change over a range of porosities from an exponential distribution to a Gaussian distribution. We thus model this behavior by using a power-exponential function and show that it can accurately represent the velocity distributions. Finally, using fully resolved velocity field and pore-geometry, we show that despite the randomness in the flow and pore space distributions, their two-point correlation functions decay extremely similarly.<br><br>Next, we extend our previous study to investigate the effect of viscoelastic fluids on particle dispersion, velocity distributions, and flow resistance in porous media. We show that long-term particle dispersion could not be modulated by using viscoelastic fluids in random porous media. However, flow resistance compared to the Newtonian case goes through three distinct regions depending on the strength of fluid elasticity. We also show that when elastic effects are strong, flow thickens and strongly fluctuates even in the absence of inertial forces.<br><br>Next, we focused our attention on flow and transport at the Darcy scale. In particular, we study a tertiary improved oil recovery technique called surfactant-polymer flooding. In this work, which has been done in collaboration with Purdue enhanced oil recovery lab, we aim at modeling coreflood experiments using 1D numerical simulations. To do so, we propose a framework in which various experiments need to be done to quantity surfactant phase behavior, polymer rheology, polymer effects on rock permeability, dispersion, and etc. Then, via a sensitivity study, we further reduce the parameter space of the problem to facilitate the model calibration process. Finally, we propose a multi-stage calibration algorithm in which two critically important parameters, namely peak pressure drop, and cumulative oil recovery factor, are matched with experimental data. To show the predictive capabilities of our framework, we numerically simulate two additional coreflood experiments and show good agreement with experimental data for both of our quantities of interest.<br><br>Lastly, we study the unstable displacement of non-aqueous phase liquids (e.g., oil) via a finite-size injection of surfactant-polymer slug in a 2-D domain with homogeneous and heterogeneous permeability fields. Unstable displacement could be detrimental to surfactant-polymer flood and thus is critically important to design it in a way that a piston-like displacement is achieved for maximum recovery. We study the effects of mobility ratio, finite-size length of surfactant-polymer slug, and heterogeneity on the effectiveness of such process by looking into recovery rate and breakthrough and removal times.