Bien qu’ayant vu le jour dans un cadre dit relativiste avec l’avènement de la théorie de la relativité générale, le lien intime existant entre géométrie de l’espace-temps d’une part, et gravitation d’autre part, peut se voir étendu aux théories dites nonrelativistes, l’exemple paradigmatique en étant la reformulation géométrique de la gravitation Newtonienne initiée par E. Cartan. De tels espace-temps nonrelativistes diffèrent structurellement de leurs homologues relativistes, ces disparités étant le plus naturellement expliquées en réinterprétant ces premiers comme réduction dimensionnelle d’espace-temps relativistes privilégiés. L’ambition de cette thèse est double : Dans une première partie, nous nous intéressons à une généralisation de la classe d’espace-temps relativistes permettant le formalisme ambiant, étudions leur interprétation géométrique ainsi que la classe élargie de structures nonrelativistes pouvant y être plongées. La seconde partie de ce manuscrit concerne le point de vue, informé par la théorie des groupes, que porte E. Cartan sur la géométrie différentielle et plus précisément l’éclairage que projettent les géométries de Cartan sur les structures nonrelativistes, à la fois dans leur définition intrinsèque et dans leur relation avec des structures relativistes au travers du formalisme ambiant. / With the advent of general relativity, the profound interaction between the geometry of spacetime and gravitational phenomena became a truism of modern physics. However, the intimate relationship between spacetime geometry and gravitation is by no means restricted to relativistic physics but can in fact be successfully applied to nonrelativistic physics, the paradigmatic example being E. Cartan geometrisation of Newtonian gravity. This geometrisation of nonrelativistic gravitation involves some nonrelativistic structures whose discrepancies in comparison with their relativistic peers are better understood when embedded inside specific classes of relativistic gravitational waves. The ambition of this Doctoral Thesis is twofold: In a first part, we discuss a generalisation of the class of gravitational waves allowing the embedding of nonrelativistic features, explore their geometric properties and the new nonrelativistic structures emerging from this study. In a second part, we advocate how the group-theoretically oriented approach of Cartan to differential geometry can shed new light on nonrelativistic structures, both in an intrinsic and ambient fashion.

Made available in DSpace on 2014-06-11T19:23:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-27Bitstream added on 2014-06-13T18:50:59Z : No. of bitstreams: 1 mendes_faa_me_ilha.pdf: 2673818 bytes, checksum: 120558e9283b734ad04dda5b07ec06d0 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O princípio de funcionamento de um sistema gas-lift é bastante simples, baseando-se na injeção de um gás inerte próximo à extremidade submersa de um tubo utilizado para ascensão do líquido (riser). Esse sistema tem sido utilizado em diversos setores da indústria, dentre os quais se destaca o setor petroquímico. Apesar de ter sido concebido há mais de um século, e a despeito do considerável número de artigos publicados sobre o assunto, vários aspectos relativos às características do escoamento bifásico dentro do riser e ao funcionamento do sistema são, ainda, pouco conhecidos. No presente trabalho, um sistema air-lift de pequeno porte foi inteiramente desenvolvido e testado, permitindo observar o comportamento do sistema quando submetido a variações na vazão de ar, na razão de submersão e na geometria do injetor – contendo três (3F) ou quinze furos (15F). Ensaios de visualização foram conduzidos, possibilitando a caracterização do escoamento bifásico no interior do riser. Medições experimentais foram, também, realizadas para a obtenção da eficiência e das curvas características do sistema. Os resultados quantitativos foram interpretados em associação com imagens estáticas do escoamento, capturadas com uma câmera fotográfica digital, e com imagens dinâmicas, tomadas com o auxílio de uma filmadora de alta velocidade. A partir destas imagens, foi possível, ainda, a estimativa de alguns importantes parâmetros característicos do escoamento pistonado, associados ao deslocamento da chamada bolha de Taylor. Os dados assim obtidos foram comparados com valores oriundos de correlações empíricas propostas por outros autores, apresentando boa concordância. Com relação aos resultados quantitativos, observou-se que, sob determinadas condições de operação, o injetor 3F é capaz de atribuir ao sistema um rendimento significativamente maior... / The operation principle of a gas-lift system is very simple: it is based on the injection of an inert gas close to the immersed edge of a tube, which is used for the rising of the liquid (riser). This system has been used in several industrial areas and more often in the petrochemical industry. Despite the fact that it was conceived over a century ago and that there have been a considerable amount of articles published on the subject, several aspects concerning the two-phase flow characteristics inside the riser as well as its operational system are still not very well known. In the present work, a small size air-lift system was thoroughly developed and tested, which facilitated the visualization of the system behavior when submitted to variations in the air flow, the immersion ratio and the injector geometry – containing three (3H) or fifteen holes (15H). Observation experiments were carried out making it possible to characterize the two-phase flow inside the riser. Experimental measurements were also taken in order to obtain the system characteristic efficiency and slopes. The quantitative results were analyzed together with the statistic images of the flow - taken by a digital photo camera, and with the dynamic images – taken by a high-speed filming camera. Through these images, it was also possible to estimate some important characteristic parameters of the slug flow associated to the displacement of the so-called Taylor bubble. The data obtained this way were compared to the figures originated from experimental correlations proposed by other authors, and they showed a fine agreement. Regarding the quantitative results, it was observed that under certain operation conditions the 3F injector is able to give the system a significantly greater efficiency than when the 15F injector is used

Made available in DSpace on 2014-12-17T14:55:00Z (GMT). No. of bitstreams: 1 SergioJGS.pdf: 1164807 bytes, checksum: 597fe8700a95271ecd0c0f3e0b460362 (MD5) Previous issue date: 2007-11-13 / This work intends to analyze the behavior of the gas flow of plunger lift wells producing to well testing separators in offshore production platforms to aim a technical procedure to estimate the gas flow during the slug production period. The motivation for this work appeared from the expectation of some wells equipped with plunger lift method by PETROBRAS in Ubarana sea field located at Rio Grande do Norte State coast where the produced fluids measurement is made in well testing separators at the platform. The oil artificial lift method called plunger lift is used when the available energy of the reservoir is not high enough to overcome all the necessary load losses to lift the oil from the bottom of the well to the surface continuously. This method consists, basically, in one free piston acting as a mechanical interface between the formation gas and the produced liquids, greatly increasing the well s lifting efficiency. A pneumatic control valve is mounted at the flow line to control the cycles. When this valve opens, the plunger starts to move from the bottom to the surface of the well lifting all the oil and gas that are above it until to reach the well test separator where the fluids are measured. The well test separator is used to measure all the volumes produced by the well during a certain period of time called production test. In most cases, the separators are designed to measure stabilized flow, in other words, reasonably constant flow by the use of level and pressure electronic controllers (PLC) and by assumption of a steady pressure inside the separator. With plunger lift wells the liquid and gas flow at the surface are cyclical and unstable what causes the appearance of slugs inside the separator, mainly in the gas phase, because introduce significant errors in the measurement system (e.g.: overrange error). The flow gas analysis proposed in this work is based on two mathematical models used together: i) a plunger lift well model proposed by Baruzzi [1] with later modifications made by Bolonhini [2] to built a plunger lift simulator; ii) a two-phase separator model (gas + liquid) based from a three-phase separator model (gas + oil + water) proposed by Nunes [3]. Based on the models above and with field data collected from the well test separator of PUB-02 platform (Ubarana sea field) it was possible to demonstrate that the output gas flow of the separator can be estimate, with a reasonable precision, from the control signal of the Pressure Control Valve (PCV). Several models of the System Identification Toolbox from MATLAB? were analyzed to evaluate which one better fit to the data collected from the field. For validation of the models, it was used the AIC criterion, as well as a variant of the cross validation criterion. The ARX model performance was the best one to fit to the data and, this way, we decided to evaluate a recursive algorithm (RARX) also with real time data. The results were quite promising that indicating the viability to estimate the output gas flow rate from a plunger lift well producing to a well test separator, with the built-in information of the control signal to the PCV / Este trabalho se prop?e a realizar uma an?lise do comportamento da vaz?o de g?s de po?os produzindo por plunger lift para vasos separadores de teste em plataformas de produ??o de petr?leo com o objetivo de propor uma t?cnica de estima??o da vaz?o durante os instantes de golfadas provocadas por estes tipos de po?os. A motiva??o para este trabalho surgiu diante da perspectiva de instala??o pela PETROBRAS de alguns po?os equipados com plunger lift no campo mar?timo de Ubarana situado na costa do Rio Grande do Norte onde a medi??o dos volumes produzidos ? feita em vaso separador na plataforma. O m?todo de eleva??o artificial de petr?leo denominado plunger lift ? utilizado quando a energia dispon?vel no reservat?rio n?o ? suficiente para vencer todas as perdas de carga necess?rias para elevar o petr?leo do fundo do po?o at? a superf?cie de forma cont?nua. O m?todo consiste, basicamente, de um pist?o livre (plunger) agindo como uma interface mec?nica entre o g?s da forma??o e os l?quidos produzidos, aumentando enormemente a efici?ncia de eleva??o. ? instalada, tamb?m, uma v?lvula de controle acionada pneumaticamente, na linha de produ??o do po?o para efetuar o controle dos ciclos. Ao ser aberta a v?lvula, o pist?o se desloca do fundo do po?o at? a superf?cie, elevando o ?leo e o g?s que se encontram acima do mesmo at? chegar no vaso separador de teste onde os fluidos ser?o medidos. O vaso separador de teste ? utilizado para fazer a aferi??o dos volumes produzidos pelo po?o durante um determinado per?odo de tempo denominado de teste de produ??o. Na maioria dos casos, os vasos separadores s?o projetados para medi??o de vaz?es estabilizadas, ou seja, razoavelmente constantes atrav?s do uso de controladores eletr?nicos de n?vel e de press?o. No caso de po?os produzindo por plunger lift, as vaz?es de l?quido e de g?s na superf?cie s?o c?clicas e de amplitude vari?vel, acarretando o surgimento de golfadas no interior do vaso separador provocando, principalmente para o caso do g?s, erros significativos no sistema de medi??o (ex.: erro de overrange ). A an?lise da vaz?o de g?s proposta neste trabalho se baseia na integra??o de dois modelos matem?ticos: i) modelagem de um po?o de plunger lift proposta por Baruzzi [1] com modifica??es efetuadas posteriormente por Bolonhini [2] na implementa??o de um simulador de plunger lift; ii) modelagem de um vaso separador bif?sico (g?s + l?quido) a partir de um modelo trif?sico (?leo + g?s + ?gua) proposto por Nunes [3]. Com base nos modelos acima e utilizando-se dados coletados no vaso separador de teste da plataforma PUB-02 (campo de Ubarana), foi poss?vel demonstrar que a vaz?o de sa?da de g?s do vaso de teste pode ser estimada, com razo?vel precis?o, a partir do sinal de controle da v?lvula controladora de press?o (PCV). Diversos modelos dispon?veis no toolbox de Identifica??o de Sistemas do MATLAB? foram analisados para se avaliar qual seria o que melhor se adaptava aos dados coletados no campo. Para a valida??o dos modelos foi usado o crit?rio de AIC, bem como uma variante do crit?rio de valida??o cruzada. O modelo ARX foi o que apresentou melhor desempenho com base nos dados coletados e, desta forma, decidiu-se avaliar tamb?m um algoritmo recursivo (RARX) com dados obtidos em tempo real. Os resultados foram bastante promissores, indicando a viabilidade de se poder estimar a vaz?o de sa?da de g?s de um po?o de plunger lift produzindo para um vaso separador de teste a partir da informa??o contida no sinal de controle da PCV

Made available in DSpace on 2014-12-17T14:55:38Z (GMT). No. of bitstreams: 1 PlinioACV.pdf: 2673165 bytes, checksum: 041961f375616fef1afc4244b3a44c02 (MD5) Previous issue date: 2009-09-02 / The purpose of this study was to develop a pilot plant which the main goal is to emulate a flow peak pressure in a separation vessel. Effect similar that is caused by the production in a slug flow in production wells equipped with the artificial lift method plunger lift. The motivation for its development was the need to test in a plant on a smaller scale, a new technique developed to estimate the gas flow in production wells equipped with plunger lift. To develop it, studies about multiphase flow effects, operation methods of artificial lift in plunger lift wells, industrial instrumentation elements, control valves, vessel sizing separators and measurement systems were done. The methodology used was the definition of process flowcharts, its parameters and how the effects needed would be generated for the success of the experiments. Therefore, control valves, the design and construction of vessels and the acquisition of other equipment used were defined. One of the vessels works as a tank of compressed air that is connected to the separation vessel and generates pulses of gas controlled by a on/off valve. With the emulator system ready, several control experiments were made, being the control of peak flow pressure generation and the flow meter the main experiments, this way, it was confirmed the efficiency of the plant usage in the problem that motivated it. It was concluded that the system is capable of generate effects of flow with peak pressure in a primary separation vessel. Studies such as the estimation of gas flow at the exit of the vessel and several academic studies can be done and tested on a smaller scale and then applied in real plants, avoiding waste of time and money. / A proposta desse trabalho foi desenvolver uma planta-piloto com o objetivo principal de emular picos de press?o de escoamentos num vaso de separa??o. Efeito semelhante ao provocado pela produ??o em forma de golfadas em po?os de produ??o equipados com o m?todo de eleva??o artificial plunger lift. A motiva??o para o desenvolvimento do mesmo foi a necessidade de se testar, numa planta em escala menor, uma nova t?cnica desenvolvida para a estima??o da vaz?o de g?s em po?os produtores equipados com plunger lift. Para seu desenvolvimento foram realizados estudos sobre efeitos dos escoamentos multif?sicos, funcionamento de m?todos de eleva??o artificial em po?os de plunger lift, dos elementos de instrumenta??o industrial, v?lvulas de controle, dimensionamento de vasos separadores e sistemas de medi??o. A metodologia utilizada foi a defini??o dos fluxogramas do processo, seus par?metros e como seriam gerados os efeitos necess?rios para o sucesso dos experimentos. Assim, foram definidas as v?lvulas de controle, o dimensionamento e constru??o dos vasos e a aquisi??o dos demais equipamentos utilizados. Um dos vasos funciona como reservat?rio de ar comprimido que, conectado ao vaso de separa??o, gera pulsos de g?s controlados por uma v?lvula on/off. Com o sistema emulador pronto, foram realizadas diversas experi?ncias de controle, sendo o controle de press?o com gera??o de picos e medi??o de vaz?o a principal experi?ncia, onde se comprovou a efici?ncia da utiliza??o da planta no problema que a motivou. Concluiu-se que o sistema ? capaz de gerar efeitos de escoamentos com picos de press?o num vaso de separa??o prim?ria. Estudos como a estima??o de vaz?o de g?s na saida do vaso e diversos estudos acad?micos poder?o ser feitos e testados numa escala menor sendo aplicados em seguida nas plantas reais, evitando perda de tempo e dinheiro

Made available in DSpace on 2014-12-17T14:55:50Z (GMT). No. of bitstreams: 1 DISSERTACAO RODRIGO SOARES SEMENTE.pdf: 1203856 bytes, checksum: 4eaca6c76cb5befb0c8681343579bc26 (MD5) Previous issue date: 2011-07-22 / Wireless sensors and actuators Networks specified by IEEE 802.15.4, are becoming increasingly being applied to instrumentation, as in instrumentation of oil wells with completion Plunger Lift type. Due to specific characteristics of the environment being installed, it s find the risk of compromising network security, and presenting several attack scenarios and the potential damage from them. It`s found the need for a more detailed security study of these networks, which calls for use of encryption algorithms, like AES-128 bits and RC6. So then it was implement the algorithms RC6 and AES-128, in an 8 bits microcontroller, and study its performance characteristics, critical for embedded applications. From these results it was developed a Hybrid Algorithm Cryptographic, ACH, which showed intermediate characteristics between the AES and RC6, more appropriate for use in applications with limitations of power consumption and memory. Also was present a comparative study of quality of security among the three algorithms, proving ACH cryptographic capability. / As redes de sensores e atuadores sem-fio especificadas pelo padr?o IEEE 802.15.4, est?o cada vez mais sendo aplicadas ? instrumenta??o, como na instrumenta??o de po?os de petr?leo com completa??o do tipo Plunger Lift. Devido ?s caracter?sticas espec?ficas do ambiente que est?o sendo instaladas, foram observados riscos de comprometimento de seguran?a da rede, e estudados v?rios cen?rios de ataques e os danos potenciais dos mesmos. Verificou-se assim a necessidade de um estudo mais detalhado de seguran?a dessas redes, que preconiza o uso de algoritmos de criptografia, como o AES-128 bits e RC6. Assim foram implementados os algoritmos AES-128 e RC6, em um microcontrolador de apenas 8 bits, e realizados estudos detalhados de suas caracter?sticas de desempenho, crucial para aplica??es embarcadas. A partir desses resultados foi criado um Algoritmo Criptogr?fico H?brido, ACH, que apresentou caracter?sticas intermedi?rias entre o AES e o RC6, mais apropriadas para uso em aplica??es com limita??es de consumo de energia e mem?ria. Tamb?m foi realizado um estudo comparativo da qualidade de seguran?a entre os tr?s algoritmos, provando a capacidade criptogr?fica do ACH.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-01-06T14:00:14Z No. of bitstreams: 1 luizmarceloamaralgalvaonunes.pdf: 1165890 bytes, checksum: 617cb8b85316ada8b08107c635bf0730 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2017-01-31T11:27:08Z (GMT) No. of bitstreams: 1 luizmarceloamaralgalvaonunes.pdf: 1165890 bytes, checksum: 617cb8b85316ada8b08107c635bf0730 (MD5) / Made available in DSpace on 2017-01-31T11:27:08Z (GMT). No. of bitstreams: 1 luizmarceloamaralgalvaonunes.pdf: 1165890 bytes, checksum: 617cb8b85316ada8b08107c635bf0730 (MD5) Previous issue date: 2016-09-06 / A Implantodontia, afim de, proporcionar melhores resultados estéticos e funcionais, tem apresentado inúmeras inovações e tecnologias visando alcançar estes objetivos associado a redução do tempo de tratamento. Contudo pacientes que apresentam a necessidade de cirurgias de reconstruções associadas a enxertos ósseos visando à instalação adequada destes implantes permanecem como desafios. Deste modo, o presente trabalho analisou o enxerto ósseo autógeno em dois diferentes períodos e avaliou os implantes instalados nestes períodos analisados, a pesquisa foi subdividida e descrita nos Capítulos à seguir. CAPITULO I: Análise histológica das características existentes no processo de incorporação e maturação óssea em áreas submetidas à cirurgia de enxerto ósseo em elevação de seio maxilar. Observou-se nos dois períodos analisados, correspondentes do processo de reparo ósseo, que foram semelhantes em ambos períodos. Deste modo, pode-se concluir que o enxerto ósseo autógeno apresenta características semelhantes na fase de incorporação (2 meses) e maturação (6 meses) o que possibilita a manipulação deste tecido na fase mais inicial sem o seu comprometimento. CAPITULO II: O propósito deste capítulo foi avaliar a osseointegração em dois períodos diferentes sendo, incorporação (2 meses) e maturação (6 meses) óssea em áreas submetidas a cirurgia de enxerto ósseo em elevação de seio maxilar e a estabilidade da prótese instalada. Observou-se nos dois períodos analisados, a incorporação óssea (2 meses) e maturação óssea (6 meses), que embora divergentes nas etapas de reparo ósseo, apresentaram resultados semelhantes para a osseointegração e estabilidade da prótese. Deste modo, pode-se concluir que a inserção de implantes osseointegráveis nestas regiões em menor período de reparo, ou seja, na fase de incorporação óssea (2 meses) não compromete a osseointegração nem tão pouco a estabilidade da prótese a longo prazo. A redução do tempo de tratamento de pacientes submetidos a cirurgias de reconstruções com enxerto ósseo em elevação de seio maxilar é possível realizando a instalação dos implantes no período de incorporação óssea. / The implantology in order to provide better aesthetic and functional results, presented numerous innovations and technologies to achieve these goals associated with reduced treatment time. However patients who have the need for reconstructive surgery associated with bone grafts seeking the proper installation of these implants remain as challenges. Thus, this work presents two studies described in the following chapters. Article I: Histological analysis of existing resources in the process of development and maturation in areas prone to bone graft surgery in sinus floor elevation. It was observed in both periods analyzed, bone repair, which were similar in both the periods. Thus, it can be concluded that autogenous grafts has similar characteristics in the incorporation phase (2 months) and mature (6 months), allowing the tissue manipulation in the initial stage without their involvement. Article II: The objective of this chapter was to evaluate the osseointegration in two different periods being, incorporation (2 months) and maturity (6 months) bone in areas subjected to bone graft surgery in sinus floor elevation and stability of the installed prosthesis. It was observed in both study periods, the bone ingrowth (2 months) and maturation (6 months), although at different stages of bone healing that showed similar results for bone integration and stability of the prosthesis. Thus, it can be concluded that the insertion of dental implants in these regions in the shortest repair, namely on bone growth phase (2 months) does not jeopardize the osseointegration or long-term stability of the prosthesis. The reduction in the treatment of patients undergoing reconstructive surgery with bone grafting time in sinus floor elevation is possible to perform the installation of implants in bone growth period.

Sprintlyftet är ett vanligt lyft som används på byggarbetsplatser idag för att montera betongbalkar och det används dessutom när betongbalkarna hanteras i fabriken där de tillverkats. Allt fler prefabricerade byggelement tillverkas och det leder till att lyftens kapacitet behöver säkerställas. I den här studien provades kapaciteten experimentiellt i ett specifikt lyft, sprintlyftet. Det är ett lyft som Abetong använder till sina betongbalkar. Det som under studien kontrollerades var om betongbalkarna idag klarar mer än vad de gjorde vid motsvarande provning för 42 år sedan. En jämförelse mellan provningar som gjordes av Abetong år 1975 och den här studiens provning visar att sprintlyften som används idag klarar av mer last än vad provningarna från 1975 gjorde. Förklaringen till det är främst att kvalitén av betongen har utvecklats under åren. / The sprint lift is a common lift used on construction sites today to mount concrete beams and it is also used when the concrete beams are handled in the factory where they were manufactured. More and more prefabricated building elements are manufactured and this means that the lifts capacity needs to be ensured. In this study, capacity was experimentally tested in a specific lift, the sprint lift. It is a lift that Abetong uses for its concrete beams. What was checked during the study was if the concrete beams today manage more than they did in the corresponding test 42 years ago. A comparison of tests made by Abetong in 1975 and this study's test show that the sprint lift used today is capable of more load than what the 1975 tests did. The explanation for this is primarily that the quality of the concrete has developed over the years.

This diploma thesis deal with project of servis lift drive by special mechanism using thrust chain. There are designed and descrobed the most importana construction unit of servis lift in the this thesis. The calculation as tha static for the main part sof the lift are included in the constructional analysis. The most attention is pay to drive, which is consist of eletric motor, clech, gearbox, break and imposition of sprocket wheel.

This master’s thesis deals with the design of the carrying frame of a lift cage with lift capacity of 675 kg. It’s main content is follow up strength analysis by Finite elements method (FEM). Thesis also contains the calculation of counterweight mass. Further is performed the calculation of the guide anchoring instituted for this steel structure and the strength analysis of the used guides according to norm ČSN EN 81-1. The thesis also includes the drawing of the carrying frame of the lift cage. Master’s thesis was carried out in co-operation with the LIFTMONT CZ company, Ltd.

Determining the hydrodynamic force acting on bubbles and particles moving parallel to a wall in a shear flow is a problem of fundamental importance, as this configuration is involved in a variety of technical and natural systems. The presence of the wall tends to increase the drag force, and more importantly causes a transverse lift force acting on the body. This thesis focuses on extending the current capability in predicting drag and lift forces on spherical bubbles and particles translating in a linear shear flow, primarily in the vicinity of a wall, and obtaining quantitative insight into the interaction mechanisms at work in the context of finite sphere Reynolds number. The investigations are performed through direct numerical simulation (DNS) using an accurate finite volume method. The first part of the thesis summarizes all expressions for the drag and lift forces available in the literature. A comprehensive review of existing results from analytical, experimental, and direct numerical simulation studies is given. The available correlations are critically assessed by comparison to data from these studies. Based on the comparison, recommendations are given which correlations to use including some new proposals, and gaps in the data are identified. The second part aims to fill the gaps mentioned above by means of DNS. Specifically, the three-dimensional flow around a non-rotating sphere translating steadily in a wall-bounded linear shear flow is investigated by solving the full Navier-Stokes equations. Numerical results and analytical expressions are combined to provide accurate semi-empirical expressions for the drag and lift forces at arbitrary Reynolds number and separation distance. Present numerical results help to rationalize and quantify the various mechanisms at work and the ways they interact. From a practical point of view, they also result in several closure models for the drag correction and transverse force, which are necessary inputs in the point-particle based Eulerian-Lagrangian simulations or in Eulerian-Eulerian simulations based on the interpenetrating continua concept.:1 INTRODUCTION 1.1 Background 1.2 Underlining mechanisms 1.3 State of the art 1.4 Motivation, goal and outline of the thesis 2 STATE OF THE ART 2.1 Statement of the problem 2.2 Overview of literatures 2.3 Unbounded linear shear flow 2.4 Linear shear flow with the wall lying in the inner region 2.5 Stagnant flow with the wall lying in the outer region 2.6 Linear shear flow with the wall lying in the outer region 2.7 Conclusions 3 NUMERICAL APPROACH AND PRELIMINARY TESTS 3.1 Numerical approach 3.2 Preliminary tests 4 CLEAN SPHERICAL BUBBLE IN WALL-BOUNDED FLOW 4.1 Characteristics of the flow field and fundamental mechanisms 4.2 Hydrodynamic forces on the bubble: fluid at rest at infinity 4.3 Hydrodynamic forces on the bubble: linear shear flow 4.4 Conclusions 5 RIGID SPHERE IN WALL-BOUNDED FLOW 5.1 Characteristics of the flow field and fundamental mechanisms 5.2 Hydrodynamic forces on the sphere: fluid at rest at infinity 5.3 Hydrodynamic forces on the sphere: Linear shear flow 5.4 Conclusions 6 CONCLUSIONS AND FUTURE WORK 6.1 Summary and conclusions 6.2 Future work 7 REFERENCE