This thesis presents the results of investigations in two areasA) Laminar helical flow of Herschel Bulkley fluids in annular space; and B) Cuttings transport in deviated wellbores. Description of area A: This is a theoretical study that consists of the modelling of non-Newtonian fluid flowing through annular space. The rheology of the fluid is represented by a three-parameter fluid model to account for a non-linear behaviour of the rheologic curve followed by the presence of a yield stress. Two distinct methodologies were used to study the effects of inner pipe rotation and inner pipe eccentricity on the velocity profiles of the annular flow. I. Laminar Helical Flow of a Herschel-Bulkley Fluid in a Concentric Annulus and its Extension to a Narrow Eccentric Annulus: The method consists of the use of the boundary conditions to enable the numerical integration of the motion equation. The subsequent extension to eccentric annuli is based on division of the annulus into sectors, where each sector is treated as an equivalent sector of a concentric annulus. Profiles of velocity presented in 2-D and 3-D contour plots explain the effects of eccentricity, inner pipe rotation and yield stress in many different situations. This analysis is useful to simulate the flow field in a borehole during directional drilling and primary cementing particularly for narrow eccentric annuli. II. Laminar Helical Flow of a Herschel-Bulkley Fluid in an Eccentric Annulus and The Special Case of a Pure Axial Flow: A new methodology to obtain the governing equations is proposed here as a first step to the solution of this complicated problem. It consists of eliminating the unknown radial and tangential pressure gradients from the equation of motion by defining vorticity between these two components of the velocity vector. The vorticity equation and the remaining axial component of the motion equation, written in bipolar co-ordinates, are then made discrete using two different finite difference approaches. Firstly, the inertial terms of both equations are made discrete using a modified upwind scheme proposed by O. Axelsson and I. Gustafsson, while the viscous terms are made discrete using central difference approximation. Secondly, the moving boundary conditions are set by enforcing continuity of pressure on the inner annular wall. The future solution of these equations will provide a very accurate model, unavailable until now, that accounts for both effects, the eccentricity and rotation of the drill string, to simulate the flow field of drilling mud in directional and horizontal wells. Description of area B: The fluid models developed are incorporated in the development of two semi-empirical correlations to predict the critical conditions of cuttings transport in deviated weI/bore. The numerical fluid models are modified to predict the velocity of the fluid at the vicinity of the cutting that is at the point of being transported. An extensive bank of data of the critical conditions of transport, emulating many different field conditions, was used in this analysis. The experimental data was provided by an industry sponsored project which did four years of experimental work in a simulated testing column to generate the data. The two semi-empirical correlations developed in this research are based on: • a dimensional analysis of the variables involved in two distinct mechanisms of transport experimentally observed: 1. Rolling or Sliding and 2. Suspension; • a force balance applied to a cutting resting on the low-side wall of an inclined annulus, under fluid dynamic conditions. The semi-empirical correlations can be used as general criteria for evaluating and correlating the effects of various parameters on cuttings transport, and as a guideline for cuttings transport programme design during directional drilling.

L'écoulement à travers un milieu poreux d'un fluide non newtonien, est un problème récurrent rencontré dans de nombreux domaines de l'industrie et dont la difficulté réside à la fois dans la géométrie complexe du milieu poreux et dans le caractère non-linéaire des matériaux utilisés. Dans cette thèse, nous adoptons une approche différente de celle menée dans les travaux antérieurs, en nous basant principalement sur l'expérimentation. En procédant à des essais systématiques d'injection dans un milieu poreux dont nous pouvons contrôler les données géométriques, nous montrons qu'un gradient de pression seuil, étant proportionnel au seuil du fluide et inversement proportionnel à la taille typique des pores, doit systématiquement être dépassé pour mettre le fluide en écoulement.En outre, nous étudions la possibilité de regrouper, via un redimensionnement, l'ensemble des résultats sur une courbe maîtresse et établir ainsi une base pour l'établissement d'une loi générale d'écoulement / The flow of a non-newtonian fluid through a porous medium is a matter of importance in several industrial applications whose difficulty arises from both the complex geometry of the porous medium and the non-linear behaviour of the complex fluids. In this thesis we investigate the flow of Herschel-Bulkley fluids via a mainly experimental approach and aim to set a generalized law for this particular type of complex fluid in porous medium.Our experimental set-up allows us to perform systematic trials of injection in model porous media whose we can control geometrical parameters. We show that a threshold pressure gradient, proportional to the yield stress and inversely proportional to the particles mean diameter has to be systematically surpassed to make the fluid flow through the porous medium. We also investigate the possibility, thanks to a resizing, to gather all the experimental data on a master curve representative of a generalized law

L'écoulement à travers un milieu poreux d'un fluide non newtonien, est un problème récurrent rencontré dans de nombreux domaines de l'industrie et dont la difficulté réside à la fois dans la géométrie complexe du milieu poreux et dans le caractère non-linéaire des matériaux utilisés. Dans cette thèse, nous adoptons une approche différente de celle menée dans les travaux antérieurs, en nous basant principalement sur l'expérimentation. En procédant à des essais systématiques d'injection dans un milieu poreux dont nous pouvons contrôler les données géométriques, nous montrons qu'un gradient de pression seuil, étant proportionnel au seuil du fluide et inversement proportionnel à la taille typique des pores, doit systématiquement être dépassé pour mettre le fluide en écoulement.En outre, nous étudions la possibilité de regrouper, via un redimensionnement, l'ensemble des résultats sur une courbe maîtresse et établir ainsi une base pour l'établissement d'une loi générale d'écoulement

This diploma thesis deals with rheological properties of mayonnaise. The theoretical part of the thesis deals with the characterization of mayonnaise and the emulsion that mayonnaise represents, it deals with production of mayonnaise, components and storage too. Another issue is about rheological properties of foods and effects that affect them. The practical part deals with evaluation of analytical indicators, such as pH, titration acidity, fat content and dry matter and rheological properties. The aim of this thesis is to determine what type of fluid mayonnaise represents. The viscosity of samples was measured by a rotary viscometer at increasing shear rate and subsequently at constant shear rate for 300 seconds. Flow curves were created from these data, they represent dependence of shear stress on shear rate, which indicate that mayonnaise is a non-Newtonian fluid that have plastic and pseudoplastic behavior. Dependence of viscosity on time were created, it indicates that mayonnaise have thixotropic behavior. Control and adjustment of rheological properties such as viscosity provide a quality product.

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-07Bitstream added on 2014-06-13T19:50:38Z : No. of bitstreams: 1 vieira_as_me_ilha.pdf: 1217264 bytes, checksum: cb21063aba699b564242c2fc4b3c3ed4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os escoamentos na superfície livre que se processam sobre forte declividade podem desenvolver instabilidades ao cabo de tempo finito. Tais instabilidades aparecem sob formas de ondas tipo “hydraulic jumps” bem espaçados e são denominadas Roll Waves. Estas ondas, longas e periódicas, podem ser contínuas ou descontínuas; contínuas em problema Shallow Water viscoso e descontínuas para o caso não viscoso. Tal fenômeno pode ser observado tanto em escoamentos naturais como em canais artificiais e vertedouros de barragens. Tratando-se de escoamento de Fluidos não newtonianos, tal fenômeno pode ser visto facilmente em lavas torrenciais, avalanchas ou “debris flows”. Nesta dissertação foram analisados matematicamente e numericamente o comportamento e as condições de existência para a formação de Roll Waves em escoamentos laminares e turbulentos. Em escoamentos turbulentos toma-se como referência os trabalhos realizados por Maciel (2001) numa reologia Binghamiana. Para escoamentos laminares, cita-se o trabalho de Mei (1994) em uma reologia tipo Power Law. No plano numérico, para escoamentos turbulentos, foram utilizadas rotinas do MATLAB® versão 6.5 e, para escoamentos laminares, rotinas em FORTRAN 90; onde pôde-se analisar e comparar resultados para diversas reologias. O foco desta dissertação foi tratar o problema Roll Waves como uma instabilidade na vizinhança do regime uniforme para Fluidos não newtonianos, em regimes turbulentos e laminares. A reologia tratada e representativa de diversos escoamentos na natureza foi a de Herschel Bulkley. A partir desta dissertação deixa-se, como perspectiva futura, um estudo mais aprofundado sob formação de ondas em fluidos hiperconcentrados tipo Herschel Bulkley com abordagem experimental a fim de validar resultados apontados nesta pesquisa. / Flows that happen over strong slope with free surface can develop instabilities after some finite time. Such wave shaped instabilities appear in the flow and are of the type “hydraulic jumps” well spaced and they are called Roll Waves. Those waves are long and periodic, continuous or discontinuous, continuous in viscous Shallow Water problems, and discontinuous for the inviscid case. Roll Waves are uncommon in natural flows, but they are common in man made channels and dams spillway. For flows of non Newtonian fluids such phenomenon can be seen easily in lava torrent, avalanche and debris flow. In this work it were mathematically and numerically analyzed the behavior and the existence conditions for the generation of Roll Waves within laminar and turbulent flows. For turbulent flows it is taken as reference the works done by Maciel (2001) dealing with a Bingham rheology. For laminar flows the reference is the work done by Mei (1994) using a Power Law rheology. Numerically, for turbulent flows it were used MATLAB® 6.5 procedures and for laminar flows FORTRAN 90 procedures were developed. Using these reference procedures it was obtained compared and analyzed results for several rheologies. This work left as future perspective a deeper study about the generation of waves in hipper concentrated fluids such as Herschel Bulkley fluid, with an experimental approach aiming to validate results produced. The focus of this work was to treat the so called Roll Waves problem as an instability in the vicinity of the uniform flow regime for non Newtonian fluids under laminar and turbulent flow regimes. The Herschel Bulkley rheology that was treated in this work is representative of several flows that happen in nature.

É notório que a degradação ambiental vem ao longo do tempo posicionando-se como um dos principais problemas do mundo moderno. Dentre as várias questões do interesse ambiental podemos destacar a ascensão da bolha de metano, em reservatórios hidrelétricos, desde o sedimento anóxico no fundo do reservatório até a interface água atmosfera. Neste contexto, a presente tese vêm propor uma nova modelagem matemática para a ascensão da bolha axissimétrica em fluidos newtonianos/nãonewtonianos e mostrar resultados numéricos simulados. Desta forma, o estado da arte estaria elevado a posição de permitir, via Matemática e Simulação Numérica-Computacional, a análise do transporte de metano em reservatórios de hidrelétricas através da bolha / It is well-known that environmental degradation has come along the time positioning as one of the main problems from modern world. Among several questions of the environmental interest may emphasize the methane bubble rise in hydroelectric reservoirs from the anoxic sediment in the bottom of reservoir until water interface atmosphere. In this context, the current thesis has come to propose a new mathematic modeling to the rise of the axisymmetric bubble in the newtonian/non-newtonian fluids and display numerical results simulated. Therefore, the state of art would be ascended to a position to permit, via Mathematics and Computing-Numeric Simulation, the analysis of transport of methane in hydroelectric reservoirs through of bubble

Des panaches sont connus pour migrer à travers le manteau ductile et quasi-Newtonien ; alors que les dikes se fracturent et se propagent dans la lithosphère solide. Cependant, la lithosphère est en fait visco-élastique. Afin de déterminer ce qui se passe dans ce cas complexe, nous avons réalisé une étude expérimentale et numérique sur le développement de panaches thermiques dans des solutions aqueuses de Carbopol, un gel de polymères formant un réseau continu d'éponges microscopiques. Ce fluide est rhéofluidifiant et présente un seuil de contrainte σ₀, de sorte que l'écoulement ne se produit que si la contrainte locale dépasse cette valeur critique σ₀. En dessous de cette valeur, le fluide agit comme un solide élastique. Les propriétés rhéologiques des solutions peuvent être systématiquement ajustées en variant la concentration de Carbopol. Le dispositif consiste en une source locale de chaleur de puissance constante placée au centre d'une cuve cubique. Selon la valeur du rapport entre la contrainte d'origine thermique et la contrainte seuil, Y₀, on peut observer trois régimes différents. A faible Y₀<Yc₁, aucun mouvement n'est détecté ; tandis que pour Yc₁<Y₀<Yc₂ une cellule se développe, puis évolue vers un panache pour Y₀>Yc₂. Nous montrons que les paramètres critiques (Yc₁,Yc₂) dépendent fortement de la géométrie du chauffage. Des mesures simultanées de température et de champs de vitesse montrent que la morphologie du panache ressemble à un doigt, contrairement à la forme de champignon rencontrée dans les fluides newtoniens. Utilisant des simulations numériques avec une description purement visqueuse, où la rhéologie du fluide est décrite par un modèle de Herschel-Bulkley régularisé, sont suffisantes pour rendre compte de la dynamique du panache. Une étude détaillée des paramètres indiquent que la dynamique du panache est gouvernée par la compétition entre la contrainte seuil, la contrainte induite par la flottabilité et les contraintes visqueuses. Nous avons identifié deux paramètres adimensionnés : le paramètre seuil Ψ comparant la contrainte induite par la flottabilité et la contrainte seuil, et le nombre de Bingham Bi comparant la contrainte seuil et les contraintes visqueuses. Un panache ne peut s'élever que si les deux paramètres sont supercritiques, i.e. la contrainte induite par la flottabilité et les contraintes visqueuses sont plus importantes que la contrainte seuil. Par conséquent, le panache peut s'arrêter avant d'atteindre la surface. Des lois d'échelles dans le conduit du panache ont été déterminées pour la vitesse, la température et la taille de la région cisaillée en régime permanent. Elles décrivent raisonnablement le comportement du conduit bien que seul l'effet rhéofluidifiant soit pris en compte. L'application de ces paramètres adimensionnés à la Terre contraignent significativement la limite de plasticité du manteau et de la lithosphère. La contrainte seuil maximale qui permet à une instabilité thermique de pénétrer dans la lithosphère ou le manteau supérieur est entre 100 kPa et 100 MPa, et elle dépend fortement de la taille et de l'anomalie de densité de l'intrusion. / Plumes are known to migrate through the ductile quasi-Newtonian mantle, while dikes fracture and propagate through the solid lithosphere. However, depending on the timescale, the lithosphere presents solid as well as viscous properties. To determine what happens in the complex case, where instabilities propagate through a visco-elastic matrix, we performed a combined study of laboratory experiments and numerical simulations. Here we investigate the development of thermal plumes in aqueous solutions of Carbopol, a polymer gel, forming a continuous network of micrometric sponges. This fluid is shear thinning and has a yield-stress σ₀, whereby flow occurs only if the local stress exceeds this critical value σ₀. Below this value, the fluid acts as an elastic solid. The rheological properties of the solutions can be systematically varied by varying the Carbopol concentration. The setup consists of a localized heat-source operated at constant power, placed at the centre of a square tank. Depending on the ratio of the thermally induced stresses and the yield stress, Y₀, three different regimes may be obtained. For low Y₀<Yc₁ no motion occurs, whereas for Yc₁<Y₀<Yc₂ a cell develops, that evolves into a plume for Y₀>Yc₂. We show that the critical parameters (Yc₁,Yc₂) strongly depend on the geometry of the heating. Combined temperature and velocity field measurements show that the morphology of the plume resembles a finger, contrary to the mushroom-like shape encountered in Newtonian fluids. Numerical simulations using a purely viscous description, where the rheology of the fluid is described by a regularized Herschel-Bulkley model, are sufficient to capture the plume dynamics. A detailed parametric study shows that the plume dynamics are governed by the interplay between yield stress, buoyancy induced stress and viscous stresses. We identify two non-dimensional parameters: the yield parameter Ψ comparing the buoyancy induced stress to the yield stress, and the Bingham number Bi comparing the yield stress to the viscous stresses. We show that a plume can rise only if both parameters are supercritical, i.e. if buoyancy induced stress and viscous stresses each overcome the yield stress. Therefore the plume may come to a halt before it reaches the surface. We propose scaling laws for the plume stem velocity, temperature and the size of the shear zone in the steady state. We show that the scaling laws describe the behaviour in the plume stem reasonably well, if the yield stress is neglected and only the shear thinning behaviour is taken into account. Applying the non-dimensional parameters to Earth places severe constraints on the strength of mantle and lithosphere. The maximum strength that allows for thermal instabilities to penetrate the lithosphere or upper mantle is in between 100 kPa and 100 MPa, and strongly depends on the size and buoyancy of the anomaly.

[pt] O tamponamento de poços de petróleo é analisado numericamente. Neste processo, um fluido mais denso (pasta de cimento) é colocado sobre outro menos denso (fluido de perfuração) em um poço vertical, resultando em uma situação de instabilidade. O escoamento resultante foi estudado de forma a avaliar se o isolamento do poço ocorreria até o momento da cura do cimento (entre 4 e 5 horas). O cimento foi modelado como fluido não-newtoniano e o fluido de perfuração foi considerado newtoniano em alguns casos e não-newtoniano nos demais casos. A solução do escoamento foi obtida numericamente, usando-se o programa ANSYS Fluent. As equações de conservação são resolvidas empregando-se o Método dos Volumes Finitos e o escoamento multifásico foi modelado utilizando-se o método Volume de Fluido. O comportamento viscoplástico não-newtoniano foi modelado empregando a equação constitutiva do fluido newtoniano generalizado, com a função de viscosidade Herschel-Bulkley. O sucesso da operação foi determinado pela combinação dos parâmetros reológicos e geométricos. O efeito dos parâmetros como a razão entre densidades e viscosidades foi investigado para uma geometria fixa (razão fixa entre o comprimento do tampão e o seu diâmetro). Além disso, a influência dessa mesma razão no processo também foi analisada enquanto outros parâmetros foram mantidos fixos. Foi demonstrado que o escoamento é muito instável e que os parâmetros estudados afetam consideravelmente a operação. / [en] The plugging process of an oil well was analyzed numerically. In this process, the denser fluid is the cement plug, which was placed above the drilling fluid in a vertical well, resulting in an unstable situation. The cement plug was modeled as non-Newtonian and the drilling fluid was considered Newtonian in some cases and non-Newtonian in other cases. The flow solution is studied using the ANSYS Fluent program. The conservation equations were solved using the Finite Volume Method, and the multiphase flow was modeled with the Volume of Fluid method. The non-Newtonian viscoplastic behavior of the cement plug was modeled with the Generalized Newtonian Fluid constitutive equation, with the Herschel-Bulkley viscosity function. The success of the operation was determined by the combination of the governing rheological and geometric parameters. The effect of the governing parameters, such as the density ratio and the viscosity ratio, were investigated for a fixed geometry and a fixed ratio between the cement plug length and diameter. Furthermore, the influence of this ratio in the process was also analyzed while others governing parameters were fixed. It was shown that the flow is highly unstable, and that the governing parameters considerably affect the operation.

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-18Bitstream added on 2014-06-13T18:10:05Z : No. of bitstreams: 1 kiryu_hs_me_ilha.pdf: 2419349 bytes, checksum: 258056fdacb79f386b2e6b238dc26028 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Esta dissertação de mestrado traz à discussão o comportamento reológico de misturas formadas por água+colóides+detritos (areia fina), visando entender e esclarecer os processos físicos e mecânicos, tais como sedimentação e ressuspensão de materiais inertes no seio da massa fluida não-newtoniana (água+colóides), bem como verificar a validade ou adeqüabilidade do modelo reológico de Herschel-Bulkley (modelo previamente investigado e validado para misturas compostas de água+colóides) para misturas viscoplásticas com presença de grãos. A variação das propriedades reológicas das misturas, em função das características físicas dos grãos (diâmetro, massa específica e área superficial), é investigada, e um modelo de estimativa de tensão crítica é apresentado. Ademais foram realizados ensaios preliminares de escoamento de fluidos hiperconcentrados em canais inclinados, na tentativa de calibrar uma lei de atrito. Dentro dessas perspectivas, a dissertação é composta de 6 Capítulos com um denso Estado da Arte que descreve os fenômenos e mecanismos que regem os escoamentos desse tipo de compósito. Com base na literatura estudada e, a partir da análise dos resultados experimentais, pôde-se concluir que, para misturas compostas de água+colóides+detritos, o comportamento reológico das misturas é o mesmo que aquele do fluido intersticial (água+colóides), desde que a homogeneidade da mistura seja garantida (não ocorrência de sedimentação e ressuspensão sucessivas). Neste caso, o modelo reológico de Herschel-Bulkley continua sendo válido para explicar as curvas de escoamento ou de fluxo das misturas viscoplásticas com grãos. Para misturas que apresentem os fenômenos de sedimentação e ressuspensão, o modelo de Bagnold, adaptado a fluidos hiperconcentrados... / This work retakes the discussion about the rheological behavior of mixtures composed by water+ kaolinitic clay+fine sand in order to investigate the physical and mechanical processes such as sedimentation and suspension of inert materials into the non-Newtonian or interstitial fluid (water+colloids), as well as verify the adaptability of the Herschel-Bulkley rheological model (model previously investigated and validated for composed mixtures of water+ kaolinitic clay) for explain the viscoplastic+coarse materials rheological properties. The variation of the rheological properties of the mixtures in function of the coarse material characteristics (diameter, specific mass and superficial area) was investigated and a model predicting yield stress was proposed. Furthermore, some tests were performed in an inclined canal to determine a friction law for this kind of fluids. Inside of these perspectives, this dissertation is composed of 6 Chapters whit a dense State of the Art describing the phenomena and their mechanisms were pointed up. Based on literature and from the experimental results, one could concluded that the viscoplastic + coarse material mixtures behavior is the same of the interstitial fluid one, since that the homogeneity of the mixture is guaranteed (not occurrence of successive sedimentation and resuspension). In this case, Herschel-Bulkley rheological model is still valid to explain the curves of flow of the viscoplastic + coarse material. For mixtures that present the phenomena of sedimentation and resuspension, Bagnoldþs model, adapted to the hyperconcentrated fluids, describes well the variations of rheological parameters in function of the shear rates applied. Finally, it could be concluded that the experiments of free surface in canals, despite partial, can... (Complete abstract click electronic access below)

É notório que a degradação ambiental vem ao longo do tempo posicionando-se como um dos principais problemas do mundo moderno. Dentre as várias questões do interesse ambiental podemos destacar a ascensão da bolha de metano, em reservatórios hidrelétricos, desde o sedimento anóxico no fundo do reservatório até a interface água atmosfera. Neste contexto, a presente tese vêm propor uma nova modelagem matemática para a ascensão da bolha axissimétrica em fluidos newtonianos/nãonewtonianos e mostrar resultados numéricos simulados. Desta forma, o estado da arte estaria elevado a posição de permitir, via Matemática e Simulação Numérica-Computacional, a análise do transporte de metano em reservatórios de hidrelétricas através da bolha / It is well-known that environmental degradation has come along the time positioning as one of the main problems from modern world. Among several questions of the environmental interest may emphasize the methane bubble rise in hydroelectric reservoirs from the anoxic sediment in the bottom of reservoir until water interface atmosphere. In this context, the current thesis has come to propose a new mathematic modeling to the rise of the axisymmetric bubble in the newtonian/non-newtonian fluids and display numerical results simulated. Therefore, the state of art would be ascended to a position to permit, via Mathematics and Computing-Numeric Simulation, the analysis of transport of methane in hydroelectric reservoirs through of bubble