A Cartesian method for solution of the steady two-dimensional Euler equations is produced. Dynamic data structures are used and both geometric and solution-based adaptations are applied. Solution adaptation is achieved through solution-based gradient information. The finite volume method is used with cell-centered approach. The solution is converged to a steady state by means of an approximate Riemann solver. Local time step is used for convergence acceleration. A multistage time stepping scheme is used to advance the solution in time. A number of internal and external flow problems are solved in order to demonstrate the efficiency and accuracy of the method.

Made available in DSpace on 2015-03-04T20:06:51Z (GMT). No. of bitstreams: 0 Previous issue date: 16 / Nenhuma / A dissertação tem por objetivo problematizar como professoras de uma escola estadual do município de Esteio, situado na região metropolitana da capital do Estado do Rio Grande do Sul, descrevem a aprendizagem da matemática escolar e, em particular, o raciocínio lógico de seus alunos. Os aportes teóricos vinculam-se ao pensamento pós-estruturalista, especialmente a algumas formulações do filósofo Michel Foucault e a ideias presentes na obra Discurso do Método, de René Descartes, principalmente aquelas ligadas à ordenação do pensamento. O material de pesquisa está constituído por documentos avaliativos da escola, em especial por 58 pareceres descritivos elaborados por cinco professoras dos anos iniciais do Ensino Fundamental da instituição estudada, e por entrevistas que com elas foram realizadas. As entrevistas foram gravadas e posteriormente transcritas. A análise do material de pesquisa possibilitou: mostrar as ressonâncias das ideias cartesianas como condutoras das condutas dos sujeitos escolares na contem / This dissertation aims at problematizing how teachers from a state school in Esteio, a town located in the metropolitan region surrounding the capital of Rio Grande do Sul, describe the learning of school mathematics, particularly their students’ logical reasoning. The theoretical bases of this investigation have been linked to the poststructuralist thought, following some formulations of Michel Foucault, and ideas from Discourse on Method, by René Descartes, mainly those linked to thought ordering. Evaluation documents of the school studied, especially 58 descriptive evaluations written by five teachers of elementary school, as well as interviews with these teachers have constituted the research material. The interviews were recorded and later transcribed. The analysis of the research material has allowed for: showing the resonances of Cartesian ideas as conducting the conducts of school subjects in contemporaneity; reflecting upon relationships between Mathematics as a foundation of reasoning and its ma

Cette thèse porte sur une méthode cartésienne parallèle pour résoudre des problèmes elliptiques avec interfaces complexes et sur son application aux problèmes elliptiques en domaine irrégulier dans le cadre d'un modèle de croissance tumorale.La méthode est basée sur un schéma aux différences finies et sa précision est d’ordre deux sur tout le domaine. L'originalité de la méthode consiste en l'utilisation d'inconnues additionnelles situées sur l'interface et qui permettent d’exprimer les conditions de transmission à l'interface. La méthode est décrite et les détails sur la parallélisation, réalisé avec la bibliothèque PETSc, sont donnés. La méthode est validée et les résultats sont comparés avec ceux d'autres méthodes du même type disponibles dans la littérature. Une étude numérique de la méthode parallélisée est fournie.La méthode est appliquée aux problèmes elliptiques dans un domaine irrégulier apparaissant dans un modèle continue et tridimensionnel de croissance tumorale, le modèle à deux espèces du type Darcy . L'approche utilisée dans cette application est basée sur la pénalisation des conditions de transmission à l'interface, afin de imposer des conditions de Neumann homogènes sur le border d'un domaine irrégulier. Les simulations du modèle sont fournies et montrent la capacité de la méthode à imposer une bonne approximation de conditions au bord considérées. / This theses deals with a parallel Cartesian method to solve elliptic problems with complex interfaces and its application to elliptic irregular domain problems in the framework of a tumor growth model.This method is based on a finite differences scheme and is second order accurate in the whole domain. The originality of the method lies in the use of additional unknowns located on the interface, allowing to express the interface transmission conditions. The method is described and the details of its parallelization, performed with the PETSc library, are provided. Numerical validations of the method follow with comparisons to other related methods in literature. A numerical study of the parallelized method is also given.Then, the method is applied to solve elliptic irregular domain problems appearing in a three-dimensional continuous tumor growth model, the two-species Darcy model. The approach used in this application is based on the penalization of the interface transmission conditions, in order to impose homogeneous Neumann boundary conditions on the border of an irregular domain. The simulations of model are provided and they show the ability of the method to impose a good approximation of the considered boundary conditions. / Questa tesi introduce un metodo parallelo su griglia cartesiana per risolvere problemi ellittici con interfacce complesse e la sua applicazione ai problemi ellittici in dominio irregolare presenti in un modello di crescita tumorale.Il metodo è basato su uno schema alle differenze finite ed è accurato al secondo ordine su tutto il dominio di calcolo. L'originalità del metodo consiste nell'introduzione di nuove incognite sull'interfaccia, le quali permettono di esprimere le condizioni di trasmissione sull'interfaccia stessa. Il metodo viene descritto e i dettagli della sua parallelizzazione, realizzata con la libreria PETSc, sono forniti. Il metodo è validato e i risultati sono confrontati con quelli di metodi dello stesso tipo trovati in letteratura. Uno studio numerico del metodo parallelizzato è inoltre prodotto.Il metodo è applicato ai problemi ellittici in dominio irregolare che compaiono in un modello continuo e tridimensionale di crescita tumorale, il modello a due specie di tipo Darcy. L'approccio utilizzato è basato sulla penalizzazione delle condizioni di trasmissione sull'interfaccia, al fine di imporre condizioni di Neumann omogenee sul bordo di un dominio irregolare. Le simulazioni del modello sono presentate e mostrano la capacità del metodo di imporre una buona approssimazione delle condizioni al bordo considerate.