Semi-solid thixoforming processes rely on a material microstructure made of globular solid grains more or less connected to each other, thus developing a solid skeleton deforming into a liquid phase. During processing, the material structure changes with the processing history due to the agglomeration of the particles and the breaking of the grains bonds. This particular evolutive microstructure makes semi-solid materials behave as solids at rest and as liquids during shearing, which causes a decrease of the viscosity and of the resistance to deformation while shearing. Thixoforming of aluminum and magnesium alloys is state of the art and a growing number of serial production lines are in operation all over the world. But there are only few applications of semi-solid processing of higher melting point alloys such as steel. This can partly be attributed to the high forming temperature combined with the intense high temperature corrosion that requires new technical solutions. However the semi-solid forming of steels reveals high potential to reduce material as well as energy consumption compared to conventional process technologies, such as casting and forging. Simulation techniques exhibit a great potential to acquire a good understanding of the semi-solid material process. Therefore, this work deals with the development of an appropriate constitutive model for semi-solid thixoforming of steel. The constitutive law should be able to simulate the complex rheology of semi-solid materials, under both steady-state and transient conditions. For example, the peak of viscosity at start of a fast loading should be reproduced. The use of a finite yield stress is appropriate because a vertical billet does not collapse under its own weight unless the liquid fraction is too high. Furthermore, this choice along with a non-rigid solid formalism allows predicting the residual stresses after cooling down to room temperature. Several one-phase material modeling have been proposed and are compared. Thermo-mechanical modeling using a thermo-elasto-viscoplastic constitutive law has been developed. The basic idea is to extend the classical isotropic hardening and viscosity laws to the non solid state by considering two non-dimensional internal parameters. The first internal parameter is the liquid fraction and depends on the temperature only. The second one is a structural parameter that characterizes the degree of structural build up in the microstructure. Those internal parameters can depend on each other. The internal parameters act on the the viscosity law and on the yield surface evolution law. Different formulations of viscosity and hardening laws have been proposed and are compared to each other. In all cases, the semi-solid state is treated as a particular case, and the constitutive modeling remains valid over the whole range of temperature, starting from room temperature to above the liquidus. These models are tested and illustrated by mean of several representative numerical applications.

La predicción precisa de los efectos producidos por el acoplamiento fluido estructura para cuerpos parcial o totalmente sumergidos, incluyendo superficies libres, es un problema de gran relevancia en la ingeniería naval así como en muchos otros campos del diseño de estructuras sometidas a la acción de fluidos.Las dificultades que se encuentran en la resolución de los problemas de interacción fluido estructura se deben principalmente a las siguientes causas:1. La dificultad de resolver numéricamente las ecuaciones de la dinámica de un fluido incompresible que, en general, si descartamos el caso más simple del modelo del flujo potencial, tienen un importante carácter no lineal. 2. Los obstáculos que se presentan al resolver la ecuación de la superficie libre, que constriñen el movimiento de las partículas a una superficie fluida de posición a priori desconocida.3. Las dificultades asociadas a la resolución del problema del movimiento de un cuerpo sumergido debido a las fuerzas de interacción, minimizando la deformación de los elementos de la malla y reduciendo, de esta manera, la necesidad del remallado.En la presente tesis se presenta un método estabilizado basado en el método de los elementos finitos que pretende solventar cada uno de los problemas anteriores. La metodología se basa en la modificación de las ecuaciones diferenciales de la dinámica de fluidos que gobiernan el flujo viscoso incompresible y el movimiento de la superficie libre, mediante la aplicación del método de cálculo finitesimal (FIC) propuesto en este trabajo.En el presente caso las ecuaciones modificadas son resueltas usando un esquema de pasos fraccionados semi-implícito y el método de los elementos finitos (FEM). El movimiento del cuerpo sumergido en el fluido debido a las fuerzas de interacción se calcula resolviendo un problema estructural dinámico, para el cual las fuerzas del fluido son las condiciones iniciales. Se incluye, además, un algoritmo para el movimiento de la malla debido a la deformación del dominio de cálculo. Este método minimiza la distorsión de la malla debida al movimiento del sólido rígido y al cambio de posición de la superficie libre. Este algoritmo se basa en la solución iterativa por el método de elementos finitos de un problema lineal, donde la malla de cálculo se considera un sólido elástico sometido a la deformación prescrita por el cambio en el dominio de cálculo. Las características de elasticidad del sólido, y en concreto su rigidez, se aplican de manera que los elementos que más se deforman tienen una rigidez mayor. Por último se presentan varios ejemplos de interés industrial, aplicación de la metodología propuesta en diferentes campos de la ingeniería naval.

The Eulerian description of dispersed two-phase flows results in a system of partial differential equations describing characteristics of the flow, namely volume fraction, density and velocity of the two phases, around any point in space over time. When pressure forces are neglected or a same pressure is considered for both phases, the resulting system is weakly hyperbolic and solutions may exhibit vacuum states (regions void of the dispersed phase) or localized unbounded singularities (delta shocks) that are not physically desirable. Therefore, it is crucial to find a physical way for preventing the formation of such undesirable solutions in weakly hyperbolic Eulerian two-phase flow models. This thesis focuses on the mathematical analysis of an Eulerian model for air- droplet flows, here called the Eulerian droplet model. This model can be seen as the sticky particle system with a source term and is successfully used for the prediction of droplet impingement and more recently for the prediction of particle flows in air- ways. However, this model includes only one-way momentum exchange coupling, and develops delta shocks and vacuum states. The main goal of this thesis is to improve this model, especially for the prevention of delta shocks and vacuum states, and the adjunction of two-way momentum exchange coupling. Using a characteristic analysis, the condition for loss of regularity of smooth solutions of the inviscid Burgers equation with a source term is established. The same condition applies to the droplet model. The Riemann problems associated, respectively, to the Burgers equation with a source term and the droplet model are solved. The characteristics are curves that tend asymptotically to straight lines. The existence of an entropic solution to the generalized Rankine-Hugoniot conditions is proven. Next, a way for preventing the formation of delta shocks and vacuum states in the model is identified and a new Eulerian droplet model is proposed. A new hierarchy of two-way coupling Eulerian models is derived. Each model is analyzed and numerical comparisons of the models are carried out. Finally, 2D computations of air-particle flows comparing the new Eulerian droplet model with the standard Eulerian droplet model are presented.

[pt] O presente trabalho busca apresentar uma proposta de inclusão de tópicos elementares da teoria de Grafos, com destaque para os Grafos Eulerianos, na educação básica. Iniciamos com uma introdução a essa teoria destacando algumas definições importantes que fundamentam o trabalho além de concepções teóricas relevantes para tratar da questão específica dos Grafos Eulerianos. Posteriormente, algumas sugestões de atividades sobre o tema, que podem ser aplicadas em qualquer nível da educação básica desde o Ensino Fundamental até o Ensino Médio, são apresentadas com o intuito de auxiliar e inspirar o professor desse segmento que esteja interessado em utilizar novas propostas na sua prática pedagógica. Assim, esse profissional pode se valer do presente trabalho como um recurso motivador para novas construções ou simplesmente adaptá-lo, alterá-lo e/ou utilizá-lo na realidade da sua sala de aula. Algumas das atividades propostas foram aplicadas com alunos do sétimo ano de uma escola pública do Rio de Janeiro e a metodologia e avaliação desta aplicação encontram-se também descritas no presente estudo. Desta forma, pretende-se promover uma reflexão sobre novas estratégias que incrementem o processo de ensino-aprendizagem da Matemática na busca de uma educação Matemática mais autônoma e mais significativa. / [en] This paper seeks to show a proposal of inclusion of elementary topics of Graphs theory, with emphasis in Eulerian graphs, on basic school. We begin with an introduction to this theory highlighting some important definitions which underpin this paper beyond relevant theoretical conceptions to deal with the specific issue of Eulerian graphs. In addition, some suggestions of activities on the subject, which can be applied in any level of basic education, from Elementary to High School, are presented with the intention of help teachers interested in using new proposals on their pedagogical practice. So they can use this material as a motivating resource for new constructions or just adapt it, change it and/or use it in his classroom routine. Some of the proposed activities were applied with seventh year students from a public school of Rio de Janeiro and the methodology and evaluation of this application are also described on this present work. Therefore it is intended to promote a reflection about new strategies that increase the teaching-learning process of Mathematics in the searching for more autonomy and more meaningful mathematical education.

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-04-25T19:44:33Z No. of bitstreams: 1 DissVSK.pdf: 2947181 bytes, checksum: 3c3bd8a24247cda4927887b3e6e3218b (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-05-02T13:09:55Z (GMT) No. of bitstreams: 1 DissVSK.pdf: 2947181 bytes, checksum: 3c3bd8a24247cda4927887b3e6e3218b (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-05-02T13:10:02Z (GMT) No. of bitstreams: 1 DissVSK.pdf: 2947181 bytes, checksum: 3c3bd8a24247cda4927887b3e6e3218b (MD5) / Made available in DSpace on 2017-05-02T13:14:36Z (GMT). No. of bitstreams: 1 DissVSK.pdf: 2947181 bytes, checksum: 3c3bd8a24247cda4927887b3e6e3218b (MD5) Previous issue date: 2016-09-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The relationship between latitude and microbial diversity in the ocean is controversial. Niche models predict higher richness at high latitudes in winter, while snapshot field-sampling point towards higher richness at intermediate latitudes, with lower values both towards equatorial and Polar Regions. However, given the dynamic nature of ocean’s ecosystem it is difficult to account for temporal variations in empirical assessments of microbial biodiversity. Here, we compared the components of diversity (richness and evenness) and microbial population stability (coefficient of variation) in two coastal ocean observatories with similar trophic state located in contrasting latitudes, one located in the Equatorial Atlantic Ocean, and one temperate located in the Northwestern Mediterranean Sea, to evaluate which factors drive the dynamics of microbial communities in each site. Our observations support the view that, as animals and plants, microbial communities exhibit higher (or at least similar) richness towards the equator, at least in the coastal ocean. We also found evidence of increasing stability with increasing evenness in tropical microbial communities when compared to the temperate ones. Temperature and silicates drove temperate free-living prokaryotic communities, while tropical ones were driven by stochastic factors such as biotic interactions with eukaryotes. We propose a conceptual framework where microbial community composition would be driven by deterministic factors in higher latitudes and once the factor temperature is removed moving towards the equator, more stochastic factors such as biotic interactions would emerge as the main factors shaping microbial communities. This study highlights the importance of comparative studies on Eulerian time-series distributed at different latitudes to fully understand the diversity patterns of microbial communities in the ocean. / A relação entre a latitude e diversidade microbiana no oceano é controversa. Modelos de nicho preveem maior riqueza em altas latitudes no inverno, enquanto amostragens pontuais indicam uma maior riqueza em latitudes intermediárias, com valores mais baixos para regiões equatoriais e polares. No entanto, dada a natureza dinâmica do ecossistema oceânico, é difícil explicar variações temporais da biodiversidade microbiana nas avaliações empíricas. Nesse trabalho comparamos os componentes da diversidade (riqueza e equitabilidade) e estabilidade das populações microbianas (coeficiente de variação) em dois observatórios oceânicos costeiros com estados tróficos semelhantes, localizados em latitudes contrastantes: um localizado no Oceano Atlântico Equatorial e um em clima temperado localizado no noroeste do Mar Mediterrâneo, a fim de avaliar quais fatores estruturam a dinâmica das comunidades microbianas em cada local. Observamos que tal como animais e plantas, as comunidades microbianas exibem maior (ou pelo menos similar) riqueza no equador pelo menos em águas costeiras. Também encontramos evidências de aumento da estabilidade com o aumento da uniformidade nas comunidades microbianas tropicais, quando comparadas com as de clima temperado. De modo geral, temperatura e silicatos foram as variáveis que condicionaram as comunidades procariotas de vida livre no observatório da região temperada, enquanto que no observatório tropical, fatores estocásticos tais como interações bióticas com eucariotos, foram os fatores que mais influenciaram as comunidades bacterianas. Assim, propomos um quadro conceitual onde a composição da comunidade microbiana seria impulsionada por fatores determinísticos em latitudes mais elevadas, enquanto que em latitudes menores, seriam determinados por fatores mais estocásticos, como interações bióticas. Nosso estudo destaca a importância de estudos comparativos utilizando series temporais Eulerianas em diferentes latitudes para entender os padrões de diversidade das comunidades microbianas no oceano.

Une méthode complètement Eulérienne reposant sur un modèle 1-fluide est présentée afinde résoudre les problèmes d’interaction fluide-structure élastique. L’interface entre le fluideet la structure élastique est représentée par une fonction level-set, transportée par le champde vitesse du fluide et résolue par un schéma d’ordre élevé WENO 5. Les déformationsélastiques sont calculées sur la grille eulérienne à l’aide des caractéristiques rétrogrades.Nous utilisons différents modèles d’hyperélasticité, afin de générer puis d’intégrer les forcesélastiques comme terme source des équations de Navier Stokes. Le couplage vitesse/pressionest résolu par une méthode de correction de pression et les équations sont discrétisées parla méthode des volumes finis sur la grille eulérienne. La principale difficulté réside dansles grands déplacements de fluide autour du solide, source d’instabilités numériques. Afind’éviter ces problèmes, nous effectuons périodiquement une redistanciation de la level-setet une extrapolation linéaire des caractéristiques rétrogrades. Dans un premier temps,nous effectuons la vérification et la validation de notre approche à l’aide de plusieurs castests comme celui proposé par Turek. Ensuite, nous appliquons notre méthode à l’étudedu phénomène d’atténuation des vagues par des structures élastiques. Il s’agit d’une desvoies possibles pour réduire l’impact des fortes houles sur notre littoral. De plus dans lalittérature et à notre connaissance, seules des structures élastiques rigides ou élastiquesmais monodimensionnelles ont été utilisées pour réaliser ces études. Nous proposons deplacer des structures élastiques sur les fonds marins et analysons leur capacité d’absorptionde l’énergie produite par les vagues. / A fully Eulerian method is developed to solve the problem of fluid-elastic structure interactionsbased on a 1-fluid method. The interface between the fluid and the elastic structureis captured by a level set function, advected by the fluid velocity and solved with a WENO5 scheme. The elastic deformations are computed in an Eulerian framework thanks to thebackward characteristics. We use the Neo Hookean or Mooney Rivlin hyperelastic modelsand the elastic forces are incorporated as a source term in the incompressible Navier-Stokesequations. The velocity/pressure coupling is solved with a pressure-correction methodand the equations are discretized by finite volume schemes on a Cartesian grid. The maindifficulty resides in that large deformations in the fluid cause numerical instabilities. Inorder to avoid these problems, we use a re-initialization process for the level set and linearextrapolation of the backward characteristics. First, we verify and validate our approachon several test cases, including the benchmark of FSI proposed by Turek. Next, we applythis method to study the wave damping phenomenon which is a mean to reduce thewaves impact on the coastline. So far, to our knowledge, only simulations with rigid orone dimensional elastic structure has been studied in the literature. We propose to placeelastic structures on the seabed and we analyse their capacity to absorb the wave energy

O fenômeno de molhamento, estudo de como um líquido se deposita em um sólido, apresenta problemas ainda em aberto, dos pontos de vista da modelagem física e da simulação numérica. O maior interesse acadêmico neste tipo de escoamento é a linha tríplice (ou linha de contato) formada da interação sólido-líquido-gás. A condição de contorno clássica de não escorregamento na interface líquido-sólido leva a uma singularidade no tensor de tensões nesta linha. Além disso, ainda não está estabelecido qual o melhor modelo para descrever o ângulo de contato formado entre a superfície livre e o substrato (o sólido). Neste trabalho, são discutidos métodos numéricos para a simulação de linhas de contato dinâmicas. Os efeitos da tensão superficial são estudados com a abordagem do princípio do trabalho virtual, o qual leva o problema à equações na formulação variacional, linguagem natural para o tratamento numérico com o método dos elementos finitos (FEM). O domínio é discretizado por uma malha não-estruturada de forma que as interfaces separadoras são explicitamente representadas pela malha. As derivadas temporais são tratadas em uma abordagem Lagrangeana-Euleriana arbitrária (ALE). Finalmente, são apresentados os resultados numéricos obtidos com o método ALE-FEM, discutindo alguns aspectos da sua convergência temporal e espacial. / Wetting phenomena, study of how of a liquid spreads out on a solid substrate, presents challenges both in physical modeling and in numerical simulation. The triple line (or contact line) formed by the solid-liquid-gas interaction has increasingly attracted the attention of the fluid dynamic community. The classical no-slip boundary condition on the liquid-solid interface leads to a singularity in the stress tensor at contact lines. Furthermore, there is no consensus on what the best model to describe the dynamics of the contact angle formed by the solid substrate and free surface. In this work, numerical methods for simulating dynamic contact lines are considered. The capillarity effects are studied in the approach of the virtual-work principle, which describes the problem in the variational formulation, natural language for numerical treatment with the finite element method (FEM). The domain is discretized by a dynamic unstructured mesh, where the separating interfaces are explicit represented by the mesh. Time derivatives present in the governing equations are treated with the arbitrary Lagrangian-Eulerian (ALE) framework. Finally, we discuss some temporal and spatial convergence issues ofthe ALE-FEM method.

On s’intéresse à la simulation d’écoulements compressibles multi-matériaux et, notamment, aux interactions fluide/structure dans les régimes transitoires et en dynamique rapide. Le but est de pouvoir décrire l’évolution de matériaux de lois de comportement très différentes à l’aide d’un modèle unique. Les milieux sont seulement différenciés par leurs équations d’état et sont séparés par une interface dite sharp. Les matériaux peuvent être des fluides ou des solides élastiques et sont soumis à de grandes déformations. Le modèle est écrit dans le formalisme eulérien. Le schéma numérique est résolu sur des grilles cartésiennes pour des simulations en trois dimensions.Une extension du modèle permet de décrire les déformations plastiques des solides. / We are interested in the simulation of compressible multimaterial flows and especially influid/structure interactions in transient states and fast dynamics. We aim to describe the evolution of materials of very different constitutive laws with an unified model. The materials are only differentiated by their own constitutive laws and are separated by a sharp interface. They can be as well fluids or elastic solids and under go large de formations. The model is written in the Eulerian framework. The numerical scheme is solved on Cartesian grids for simulations in three dimensions. An extension of the elastic model is added to describe the plastic deformations of solids.

Le travail présenté concerne le développement d’un cadre d’applications pour le traitement d’écoulements dispersés, tenant compte de l’effet de la coagulation sur la distribution des tailles des particules. Nous explorons également quelques techniques de validation expérimentale. Les modèles sont valables pour un écoulement incompressible et isotherme, avec des particules qui ont un temps de relaxation faible en comparaison à celui du fluide. Pour la phase dispersée, une méthode eulérienne est utilisée, ce qui permet d’extrapoler la vitesse des particules de celle du fluide. La distribution des tailles est modélisée à l’aide du « Direct Quadrature Method of Moments ». Cette approche permet de résoudre des équations de transport pour les poids et les abscisses d’une approximation de la distribution à l’aide des fonctions Dirac delta. L’effet de la coagulation est pris en compte à l’aide d’un noyau de collisions qui utilise la vitesse instantanée du fluide. Toutes les équations de transport sont résolues à l’aide de la méthode des éléments finis. Pour le fluide, les stabilisations « Streamline Upwind » et « Pressure Stabilized Petrov-Galerkin » sont utilisées ensemble avec une stabilisation grad-div. Afin de limiter le temps de calcul pour une simulation directe, une formulation utilisant un traitement explicite des termes d’advection est proposée. Avec l’apparition de gradients élevés, les équations de transport pour les particules nécessitent une stabilisation supplémentaire. Tout le travail est disponible dans le projet de logiciel libre Coolfluid 3, en utilisant un langage spécifique permettant une implémentation directe pour des modèles en éléments finis. Le code qui en résulte ressemble à la forme variationnelle des équations utilisées. Le programme est générique en termes de dimensions spatiales et de type d’éléments. Une première validation utilise des résultats trouvés dans la littérature comme référence. La précision des méthodes est vérifiée à l’aide des vortices Taylor-Green. Pour l’écoulement et les concentrations des particules, une simulation directe d’un canal turbulent est effectuée. Le noyau de coagulation est vérifié à l’aide de particules de différentes tailles qui tombent à travers un vortex Burgers. Finalement, quelques techniques de validation expérimentale sont utilisées dans une cellule d’essai. La technique « Particle Image Velocimetry » est utilisée pour les vitesses du fluide, tandis que la distribution des tailles est mesurée à l’aide du « Phase Doppler Anemometry » et « Multiple Wavelength Light Extinction ». La technique d’extinction de lumière est capable de produire des distributions des tailles qui peuvent être comparées facilement avec les résultats numériques. / The present work deals with the development of a framework for the modeling of dispersed flows, including the effect of coagulation on the particle size distribution. We also explore some techniques for experimental validation. Models are developed for incompressible, isothermal flow containing particles that have a small relaxation time compared to the fluid time scale. For the dispersed phase, an equilibrium Eulerian approach is used, extrapolating the particle velocity from the fluid velocity. The size distribution is modeled using the Direct Quadrature Method of Moments. In practice, this results in solving transport equations for the weights and abscissa of a Dirac delta approximation of the size distribution. To model the effect of coagulation, a collision kernel that makes use of the resolved instantaneous velocity is developed. All transport equations are solved using the Finite Element Method. For the fluid, the Streamline Upwind and Pressure Stabilized Petrov-Galerkin method are used, with additional grad-div stabilization. To decrease the solution time for DNS, a segregated formulation with an explicit advection term is proposed. The particle transport equations require cross-wind diffusion in addition to the streamline upwind stabilization when large gradients occur. All work is available in the open source Coolfluid 3 framework, using an Embedded Domain Specific Language we developed for the implementation of finite element models. The resulting code closely resembles the variational form of the equations and is generic in terms of element type and the number of spatial dimensions. A first validation uses literature results as reference. Correctness and accuracy of the methods are verified using the Taylor-Green vortex flow. For the fluid and particle concentration, direct numerical simulation of a turbulent channel flow is performed. The particle coagulation kernel is tested using particles of different sizes falling through a Burgers vortex. Finally, some experimental validation techniques are used on a small test chamber. Particle image velocimetry is used for the fluid motion, while the size distributions are measured using Phase Doppler Anemometry and Multiple Wavelength Light Extinction. The light extinction technique was found to produce size distributions that could provide valuable reference data for our particle model.

Summer monsoon current (SMC) in the north Indian Ocean (NIO) is an open ocean current that flows eastward and enter into Bay of Bengal (BoB) during southwest monsoon (June–September). South of Sri Lanka, the SMC turns north-eastward instead of following eastward course and feeds into the BoB. Understanding the dynamics of SMC is crucial to understanding the interaction between Arabian sea (AS) and BoB. In the year 2009, the current moved north-eastward, meandered and then finally terminated into the southeast BoB. The northward bend of the current southeast of Sri Lanka has been attributed to the interaction of the eastward SMC with Rossby waves radiated from eastern boundary. An anticyclonic vortex formed right of the north-eastward meandering current which was associated with significantly high speeds. Reasons behind the unusually high speeds of SMC in this region remain unknown. Processes involved in the interaction of eddies with eastward SMC, the meandering of the current and its ultimate termination in southeast BoB are also not understood. Our study investigates the evolution, intensfication and meandering of SMC around Sri Lanka using an Indian Ocean general circulation model (MOM4p1) simulation for the year 2009. The model simulation, when compared with observational data OSCAR, showed good agreement. The study also explores the role of local and remote forcing in modulating the dynamics of SMC in the region. An eddy kinetic energy budget analysis for the region was performed which indicates the region to be a zone of significant eddy activity. Both barotropic, baroclinic instabilities were found to be the dominant mechanisms behind the generation of eddies. Based on eddy energetic analysis, the evolution of SMC was classified into stages i ii of onset, intensification, anticyclonic bend, anticyclonic vortices formation and meandering. Effect of eddies on mean flow were studied with the help of a transformed Eulerian mean (TEM) approach under quasi-geostrophic approximation. Eddy potential vorticity fluxes appearing in the TEM momentum equation and eddy enstrophy decay, divergence of eddy enstrophy advection from eddy enstrophy equation, helped to un-derstand when, where and how the eddies tended to drive the mean flow. Rossby waves and other westward propagating eddies arriving from the east, energise the SMC in June and induce an acceleration tendency on the mean flow through regions associated with upgradient eddy potential vorticity flux. In addition to the eddies, local winds also play a crucial role in driving the mean flow. Wind power, surface mean ocean kinetic energy and available potential energy (APE) were computed, integrated over the region of interest and compared to each other. The effect of local winds appear to be predominant in driving the mean flows as it not only increases the surface mean kinetic energy of the SMC but also raises the isopycnals and builds up large amount of APE in the ocean. Baroclinic instability takes place in late July and early August associated with the release of APE which flattens the isopycnals and thus weakens the SMC. Consequently the SMC meanders in course of time and flows into southeast BoB.