[pt] Neste trabalho aplicamos o método Lattice Boltzmann (LBM) para simular os processos de reações químicas que ocorrem na interação entre o fluido e a fase sólida, modificando o meio poroso. Para isso apresentaremos como o método LBM aborda a simulação do escoamento de fluido em um meio poroso irregular para os casos de um ou mais fluidos incluindo o processo de dissolução química. A partir dos processos anteriores, propomos uma modificação onde a dissolução possa ocorrer como uma característica do fluido que interage com a fase sólida. Ao abordar a dissolução como característica da interação do fluido com a fase sólida, é possível ter uma maior compreensão de como o fluido pode modificar a geometria do meio poroso e impactar nas mudanças de fluxo. A proposta de modificação foi avaliada em alguns casos em que o fluxo no meio poroso é bem definido: o canal aberto, canal com cilindros e em um meio poroso de geometria complexa. A proposta foi estendida para a simulação em um meio poroso 3D, onde analisamos como a dissolução foi impactada pela presença de forças externas como a gravidade. / [en] In this work, we apply the Lattice Boltzmann (LBM) method to simulate the chemical reaction processes that occur in the interaction between the fluid and the solid phase, modifying the porous medium. For this, we will present how the LBM method approaches fluid flow simulation in an irregular porous medium for cases of one or more fluids, including the chemical dissolution process. Based on the previous processes, we propose a modification where dissolution can occur as a characteristic of the fluid that interacts with the solid phase. By approaching dissolution as a characteristic of the interaction of the fluid with the solid phase, it is possible to better understand how the fluid can modify the geometry of the porous medium and impact the flow changes. The modification proposal was evaluated in some cases where the flow in the porous medium is well defined: the open channel, a channel with cylinders, and a porous medium with complex geometry. The proposal was extended to the simulation in a 3D porous medium, where we analyzed how the dissolution was impacted by external forces such as gravity.

[pt] O principal objetivo deste trabalho é preencher canais turbidíticos com alguma propriedade petrofísica, como a permeabilidade. Estes canais são geometricamente limitados por lobos turbidíticos, gerando a simulação de um sistema deposicional. Simulações numéricas são usadas para tentar ajustar a permeabilidade a um caso de referência por meio de uma função objetivo. Um simulador convencional de diferenças finitas foi usado para comparar os dados de referência com as simulações, obtendo resultados próximos. / [en] The main objective of this work is to populate turbidite channels with some petrophysical property such as permeability. These channels are geometrically constrained by turbidite lobes creating a simulated depositional system. Numerical simulations are used to try to fit the permeability field to a reference case through an objective function. A conventional finite difference simulator was used to compare the reference data to the simulations, obtaining close results.

Dans les nouveaux protocoles thérapeutiques par voie inhalée, le dosage des particules actives reste un problème complexe qui dépend de trois principaux facteurs : leur taille, la dynamique des flux et les variations de calibre bronchique. La solution nécessite de disposer d'un modèle de distribution des gaz et aérosols administrés dans les poumons. Ventilation pulmonaire et effets du cycle respiratoire sur la dynamique des fluides deviennent deux enjeux clés de la pratique clinique.<br /><br />Dans ce contexte, le projet RNTS RMOD a pour objectif de développer un simulateur morpho-fonctionnel des voies respiratoires pour l'aide au diagnostic, au geste médico-chirurgical et à l'administration de médicaments par inhalation.<br /><br />Contribuant au projet RMOD, la recherche développée dans cette thèse propose une modélisation in-silico de la structure des voies aériennes supérieures (VAS) et proximales (VAP) à partir d'examens tomodensitométriques (TDM). L'investigation morphologique et la simulation fonctionnelle bénéficient alors de géométries 3D réelles, adaptées au patient et spécifiques des pathologies rencontrées.<br /><br />La modélisation développée fait coopérer des méthodes originales de segmentation, de construction de surface maillée et d'analyse morpho-fonctionnelle.<br /><br />La segmentation des VAP est obtenue par un schéma diffusif et agrégatif gouverné par un modèle markovien, dont l'initialisation repose sur l'opérateur de coût de connexion sous contrainte topographique. De cette segmentation, l'axe central de l'arbre bronchique est extrait de manière robuste et précise en combinant information de distance, propagation de fronts, et partition conditionnelle locale. Cet axe central est représenté sous forme d'une structure hiérarchique multivaluée synthétisant caractéristiques topologiques et géométriques de l'arbre bronchique. Une surface maillée est ensuite construite en appliquant une procédure de Marching Cubes adaptative, les paramètres des différents filtres mis en jeu étant automatiquement ajustés aux caractéristiques locales du réseau bronchique conditionnellement aux attributs de l'axe central.<br /><br />La segmentation des VAS repose sur une propagation markovienne exploitant les variations locales de densité. L'initialisation combine morphologie mathématique et information de contour afin de garantir la robustesse à la topologie. Une procédure de type triangulation de Delaunay restreinte à une surface fournit ensuite la représentation maillée des VAS. Il est établi que la topologie et la géométrie des structures complexes composant les VAS sont effectivement préservées.<br /><br />Pour permettre aux médecins de valider les modèles maillés ainsi construits, un environnement virtuel 3D convivial et interactif a été réalisé. En outre, la morphologie des voies aériennes exo- et endo-luminale est analysée de façon automatique à partir de simulations d'écoulement pour des géométries réelles.<br /><br />Enfin, une modélisation unifiée des VAP et VAS est obtenue pour la première fois. Elle démontre la pertinence des approches développées. Elle ouvre la voie à la construction de modèles in-silico complets de l'appareil respiratoire ainsi qu'aux études fonctionnelles prenant en compte les paramètres morphologiques susceptibles d'influer localement ou globalement sur la dynamique des écoulements.

Made available in DSpace on 2016-12-23T14:04:30Z (GMT). No. of bitstreams: 1 Wesley Jose Nunes Pinto.pdf: 2090367 bytes, checksum: e676fde8423a3a2cfeac61da24020ea8 (MD5) Previous issue date: 2013-08-19 / Neste estudo foi aplicado do método numérico, sem malhas, baseado em partículas, denominado SPH (Smoothed Particles Hydrodynamics). E um código numérico na linguagem computacional FORTRAN foi utilizado para solucionar as equações de Navier-Stokes. O clássico problema da literatura da dinâmica dos fluidos Computacional, denotado como problema da cavidade quadrada bidimensional (Shear-Driven Cavity Flow) , foi estudado com a intenção de verificar o comportamento do código numérico em relação a resultados específicos já existentes do assunto. O citado problema físico das cavidades abertas é amplamente empregado como benchmark, visando a validação do método numérico utilizado no trabalho desenvolvido na pesquisa. O trabalho de análise e validação do código numérico foi dividido em três seções: a primeira lista as localizações dos centros dos vórtices principais gerados pelo escoamento na aresta superior das cavidades; a segunda plota os perfis das componentes das velocidades centrais das cavidades; e a terceira: lista os desvios absolutos dos perfis das velocidades centrais do presente trabalho, comparados com dados de outros estudos. Constata-se que o método SPH apresentou boa acurácia nas simulações realizadas, obtendo boa concordância entre os resultados das simulações dinâmicas com os dados de referências, validando-se o modelo numérico proposto, tendo melhores resultados para baixos números de Reynolds / In this study, it was applied the numerical method, grid-free, based on particles named SPH (Smoothed Particles Hydrodynamics). Also, a numerical code in the computer language FORTRAN was used to solve the Navier-Stokes Equations. This classic problem of the literature related to Computational Fluid Dynamics indicated as Shear-Driven Cavity Flow was studied to check the behavior of the numerical code regarding specific existing results. Such problem is highly used as Benchmark, aiming the validation of the numerical method used to develop the research. The analysis and validation of the numerical code was divided into three sections: the first one lists the location of the centre of the main vortex generated by the flow of the upper edge of the cavities; the second one plots the profiles of the components of the central speed of the cavities; the third one lists the absolute deviation of the profiles of the central speed of this study compared with other cases data. It is established that the SPH Method presented accuracy in the performed simulations, in a consonance between the results of the dynamic simulations and the reference data, thus the proposed numerical model was validated with better results for low Reynolds numbers

Well logs and formation testers are routinely used for detection and quantification of hydrocarbon reserves. Overbalanced drilling causes invasion of mud filtrate into permeable rocks, hence radial displacement of in-situ saturating fluids away from the wellbore. The spatial distribution of fluids in the near-wellbore region remains affected by a multitude of petrophysical and fluid factors originating from the process of mud-filtrate invasion. Consequently, depending on the type of drilling mud (e.g. water- and oil-base muds) and the influence of mud filtrate, well logs and formation-tester measurements are sensitive to a combination of in-situ (original) fluids and mud filtrate in addition to petrophysical properties of the invaded formations. This behavior can often impair the reliable assessment of hydrocarbon saturation and formation storage/mobility. The effect of mud-filtrate invasion on well logs and formation-tester measurements acquired in vertical wells has been extensively documented in the past. Much work is still needed to understand and quantify the influence of mud-filtrate invasion on well logs acquired in horizontal and deviated wells, where the spatial distribution of fluids in the near-wellbore region is not axial-symmetric in general, and can be appreciably affected by gravity segregation, permeability anisotropy, capillary pressure, and flow barriers. This dissertation develops a general algorithm to simulate the process of mud-filtrate invasion in vertical and deviated wells for drilling conditions that involve water- and oil-base mud. The algorithm is formulated in cylindrical coordinates to take advantage of the geometrical embedding imposed by the wellbore in the spatial distribution of fluids within invaded formations. In addition, the algorithm reproduces the formation of mudcake due to invasion in permeable formations and allows the simulation of pressure and fractional flow-rate measurements acquired with dual-packer and point-probe formation testers after the onset of invasion. An equation-of-state (EOS) formulation is invoked to simulate invasion with both water- and oil-base muds into rock formations saturated with water, oil, gas, or stable combinations of the three fluids. The algorithm also allows the simulation of physical dispersion, fluid miscibility, and wettability alteration. Discretized fluid flow equations are solved with an implicit pressure and explicit concentration (IMPEC) scheme. Thermodynamic equilibrium and mass balance, together with volume constraint equations govern the time-space evolution of molar and fluid-phase concentrations. Calculations of pressure-volume-temperature (PVT) properties of the hydrocarbon phase are performed with Peng-Robinson's equation of state. A full-tensor permeability formulation is implemented with mass balance equations to accurately model fluid flow behavior in horizontal and deviated wells. The simulator is rigorously and successfully verified with both analytical solutions and commercial simulators. Numerical simulations performed over a wide range of fluid and petrophysical conditions confirm the strong influence that well deviation angle can have on the spatial distribution of fluid saturation resulting from invasion, especially in the vicinity of flow barriers. Analysis on the effect of physical dispersion on the radial distribution of salt concentration shows that electrical resistivity logs could be greatly affected by salt dispersivity when the invading fluid has lower salinity than in-situ water. The effect of emulsifiers and oil-wetting agents present in oil-base mud was studied to quantify wettability alteration and changes in residual water saturation. It was found that wettability alteration releases a fraction of otherwise irreducible water during invasion and this causes electrical resistivity logs to exhibit an abnormal trend from shallow- to deep-sensing apparent resistivity. Simulation of formation-tester measurements acquired in deviated wells indicates that (i) invasion increases the pressure drop during both drawdown and buildup regimes, (ii) bed-boundary effects increase as the wellbore deviation angle increases, and (iii) a probe facing upward around the perimeter of the wellbore achieves the fastest fluid clean-up when the density of invading fluid is larger than that of in-situ fluid. / text

The quest to achieve high resolution in ion mobility spectrometry (IMS) has continued to challenge scientist and engineers in the field of separation science. The low resolution presently attainable in IMS has continued to negatively impact its utility and acceptance. Until now, efforts to improve the resolution have mainly focused on better instrumentation and detection methods. However, since the resolution of IMS is diffusion limited, it makes sense to address this limitation in order to attain high resolution. This dissertation presents a new IMS technique, which utilizes a high electric field and opposing high gas flow velocity with the aim to improve resolution. This approach essentially reduces the residence time of ions in the analyzer. This new technique is called "counter-flow ion mobility analysis" (CIMA). Theoretical modeling of this new technique predicted that a resolution of over 1000 is possible, which is over one order of magnitude better than that of conventional IMS techniques currently used. A wind tunnel was designed and constructed to produce a plug gas flow profile that is needed for CIMA. The test region of the wind tunnel was used as the CIMA analyzer region and was constructed from power circuit boards, PCBs, (top and bottom walls) and conductive plastic side walls. An inclined electric field was created by applying suitable voltages to multiple electrode traces on the PCBs. This inclined field, when resolved into its x- and y-components, was used to oppose the counter-gas flow and transport the ions to the detector, respectively. The results obtained did not show an improvement over conventional IMS techniques because of a limitation in the voltage that could be applied to the analyzer region. However, the results predict that high resolution is possible if (1) the ratio of the electric fields in the horizontal (x direction) to the vertical (y direction) is within the range of 2--0.5, (2) very high electric field and high gas flow velocities are applied, and (3) wall effects in the counter-flow gas profile are eliminated. While the resolution obtained using the present instrumentation is far from what was predicted, the foundation for ultimately achieving high resolution has been laid. The use of a wind tunnel has made the instrumentation possible. As far as the author knows, this is the first time a wind tunnel has been used in chemical measurement instrumentation. Chapter 5 of this dissertation, reports a method developed for predicting the reduced mobility constants, of chemical compounds. This method uses a purely statistical regression analysis for a wide range of compounds which is different from similar methods that use a neural network. The calculated value for this method was 87.4% when calculated values were plotted against experimental K0 values, which was close to the value for the neural network method (i.e., 88.7%).