De acordo com o modelo sequencial de acreção, os planetas gigantes se formam através de um núcleo sólido a partir da captura de planetesimais. Esse núcleo, atingindo uma determinada massa, é capaz de capturar o gás residual do disco protoplanetário que constituirá o seu envelope, formando, então, um planeta gigante (Mizuno, 1980; Pollack et al., 1996). A parte crtica desse cenário está no ajuste dos tempos de formação do núcleo sólido, de captura do gás e dos processos de migração planetária com o tempo de vida do disco (Mordasini et al., 2010). Resultados numéricos mostram que o tempo necessário para a formação de um planeta gigante é muito alto em relação ao tempo de vida do disco, e, que a migração planetária pode ser muito rápida, levando os planetas a carem na estrela antes de sua completa formação. Em geral, os trabalhos sobre formação planetária tratam a migração do planeta utilizando prescrições analíticas (Fortier et al., 2013). No entanto, diversos efeitos associados à termodinâmica do disco de gás fazem com que esses modelos analíticos sejam limitados para lidar com a migração planetária (Paardekooper et al., 2010). De fato, para lidar com a migração planetária de tipo I, esses resultados analíticos se utilizam de discos de gás fisicamente simples e da linearização das equações da hidrodinâmica (Meyer-Vernet e Sicardy, 1987; Tanaka et al., 2002). Para a migração de tipo II, a situação é ainda mais complicada, já que a alta massa do planeta cria um gap em torno da órbita planetária, que impõe uma quebra da linearidade, impossibilitando a obtenção de uma prescrição analtica (Bryden e Lin, 1999). Assim, os resultados numéricos obtidos a partir de simuladores hidrodinâmicos, como o FARGO3D (Masset, 2000; Bentez-Llambay e Masset, 2016), ZEUS (Stone e Norman, 1992), PLUTO (Mignone et al., 2012), entre outros, são essenciais para uma análise mais robusta dos processos de migração planetária dentro de uma gama maior de condições fsicas para o disco de gás. No entanto, os simuladores hidrodinâmicos que tratam da interação do planeta com o disco de gás, em geral, não possuem um modelo para formação planetária. Em alguns deles, modelos para acreção de gás são construdos com base no regime de runaway dessa acreção (Kley, 1999). Todavia, a acreção de sólidos e a acreção de gás para planetas de baixa massa, na maior parte dos casos, não são levadas em consideração. Boa parte disso se deve ao fato de os modelos de formação planetária usarem simulações N-corpos, que, aliados ao código hidrodinâmico, seriam altamente custosos computacionalmente. Assim, torna-se necessário o uso de modelos alternativos para a formação planetária, que sejam capazes de reproduzir os resultados de uma simulação N-corpos de forma confiável. Construir um modelo que considera a acreção de sólidos e gás é uma tarefa árdua e ao mesmo tempo desafiadora. Assim, o presente projeto propõe a implementação de um cenário fisicamente plausível para a formação planetária dentro do código magneto hidrodinâmico FARGO3D. Para modelar a acreção de planetesimais, usamos como base os trabalhos de Guilera et al. (2010) e Fortier et al. (2013), que utilizam um modelo estatstico para determinar a taxa de acreção de planetesimais (Inaba et al., 2001). Esse modelo será implementado pela primeira vez no FARGO3D. Atualmente, sabe-se que a acreção de peebles (material sólido entre cm e mm) tem um impacto importante na formação planetária (Lambrechts e Johansen, 2014; Guilera, 2016; Johansen e Lambrechts, 2017). No entanto, núcleos de poucas massas terrestres possuem um envelope planetário que poderia destruir esses pebbles antes dele alcançar o núcleo (Venturini et al., 2015). Nesta tese, iremos nos preocupar apenas com a acreção de planetesimais, deixando o estudo do pebbles para trabalhos futuros. Para a acreção de gás, iremos modificar o modelo de Kley (1999) incorporado no FARGO antecessor. Essas modificações visam incorporar o raio de Bondi (Bondi, 1952) para determinar a zona de acreção, o efeito da altura do disco e a mudança na taxa de acreção de gás de acordo com a massa do planeta. As modificações implementadas no modelo de acreção de gás foram realizadas com base nos trabalhos de Dürmann e Kley (2015), Russell (2011) e Fortier et al. (2013). A adaptação no código de acreção de gás para levar em conta uma faixa maior de massas planetárias foi realizada utilizando a escala de tempo de Kelvin-Helmoltz. Para isso, seguimos o trabalho de Ikoma et al. (2000) e Idae Lin (2004b). Para testar o modelo de formação planetária no FARGO3D, a simulação padrão para o disco de gás utilizada nesta tese adota um disco bidimensional fino com taxa de acreção constante. A razão de aspecto do disco será de h = 0.05 com um fator de curvatura de = 0.0. Esses valores são consistentes com a teoria de discos finos e são usados nas maioria das simulações que envolvem discos de acreção (Bell et al., 1997; Frank et al., 2002). O disco é assumido localmente isotérmico e a viscosidade do disco é dirigida pela prescrição de Shakura e Sunyaev (1973), com = 0.03. O modelo de disco é simplificado e caractersticas importantes podem influenciar no processo de formação e migração planetária, como as trocas de energia. No entanto, ele é um ótimo modelo inicial para um teste consistente do modelo de formação planetária implementado, já que possui um resultado analtico conhecido. Casos mais complexos serão explorados em trabalhos futuros. Com o modelo de formação planetária implementado, foi possível estudar simultânea- mente a formação e a migração do planeta dentro do simulador hidrodinâmico. Isto é, analisamos a escala de tempo envolvida no processo de migração em conjunto com a escala de tempo da formação planetária para vários parâmetros fsicos envolvidos no modelo. A análise revelou, para nosso modelo de disco, que a escala de crescimento do planeta conseguiu se manter mais baixa que a escala de migração, mesmo quando o planeta atravessou a linha de gelo, local onde há menor quantidade de material disponvel para a acreção de sólidos. Assim, para planetesimais pequenos (raio 0.1 km), foi possvel obter planetas com massas próximas de 5 massas de Júpiter em regiões entre 0.5 e 1 ua, num tempo menor que o tempo de vida do disco. Vale ressaltar que esta tese conta com uma descrição detalhada de como implementar o modelo dentro do FARGO3D, incluindo um apêndice com o programa comentado linha a linha. O intuito é que o leitor possa usar esse modelo de formação e migração planetária para obter novos resultados e vnculos sobre a formação de sistemas exoplanetários ou do nosso Sistema Solar, assim como usar em qualquer outra aplicação que julgar necessária. / According to the sequential model of accretion, the giant planets are formed from a solid nucleus by capturing planetesimals. When this nucleus reaches a certain mass, it captures the residual gas of the protoplanetary disc that will constitute its envelope, forming a giant planet (Mizuno, 1980; Pollack et al., 1996). The critical part of this scenario is to adjust the planet formation and migration timescales with the lifetime of the disk (Mordasini et al., 2010). Numerical results show that the time required for the formation of a giant planet is very long compared to the lifetime of the disc, and that planetary migration can be very rapid, causing the planets to fall into the star before their full formation. In general, works on planetary formation use analytical models to deal with the migration of the planets (Fortier et al., 2013). However, these analytical models are limited given that they do not include several effects associated with the thermodynamics of the gas disc (Paardekooper et al., 2010). Indeed, in order to deal with planetary migration of type I, these analytical models use physically simple gas discs and rely on the linearization of the hydrodynamic equations (Meyer-Vernet e Sicardy, 1987; Tanaka et al., 2002). For the type II migration, the situation is even more complicated. This is due to the fact that the large mass of the planet creates a gap around the orbit of the planet, causing nonlinearities (Bryden e Lin, 1999). Thus, the numerical results obtained using hydrodynamic simulators, such as FARGO3D (Masset, 2000; Bentez-Llambay e Masset, 2016), ZEUS (Stone e Norman, 1992), PLUTO (Mignone et al., 2012), among others, are essential for a more robust analysis of the processes of planetary migration considering a wider range of physical conditions for the gas disc. However, in general, hydrodynamic simulators do not have a model for the planetaryformation. In some of them, models for gas accretion are built based of the runaway regime of accretion (Kley, 1999). Furthermore, the accretion of solids and the accretion of gas for low mass planets are not considered in most of the cases. This is mainly due to the fact that the models of planetary formation use N-body simulations that are computationally very expensive. Thus, it is necessary to use alternative models for the planetary formation, that are capable of reproducing the same results of an N-body simulation. Building a complete model that takes into account all these processes is a hard and challenging task. So, this project aims the implementation of a physically plausible scenario for a planetary formation inside the magneto-hydrodynamic code FARGO3D. For the accretion model we use the works by Guilera et al. (2010) and Fortier et al. (2013), which employ an statistical model to determine the accretion rate of planetesimals (Inaba et al., 2001). This model will be implemented for the first time in the FARGO3D code. It is now known that the accretion of peebles (material with size ranging from mm and cm) has a important impact on the planetary formation (Lambrechts e Johansen, 2014; Guilera, 2016; Johansen e Lambrechts, 2017), although cores with a few masses of the Earth have a planetary envelope that could destroy those pebbles, before they reach the nucleus (Venturini et al., 2015). In this thesis, we will only deal with the accretion of planetesimals, leaving the study of pebbles for future work. For the gas accretion, we use a modified model based on Kley (1999). The modifications aim to incorporate the Bondi radius (Bondi, 1952) to determine the accretion zone, the effect of the height of the disc and the frequency of accretion. The implemented modifications are based on the works by Dürmann e Kley (2015), Russell (2011) and Fortier et al. (2013). The adaptation in the gas accretion code to take into account a wider range of planetary masses was achieved using the Kelvin-Helmoltz timescale, according to the works by Ikoma et al. (2000) and Ida e Lin (2004b). To test the planetary formation model in FARGO3D, the standard simulation for the gas disc uses a bi-dimensional thin disc. The discs aspect ratio is h = 0.05 with a curvature factor of = 0.0. These values are consistent with the theory of thin dics and are used in most of the simulations for accretion discs (Bell et al., 1997; Frank et al., 2002). The disc is assumed to be locally isothermal and the viscosity of the disc is driven by the prescription from Shakura e Sunyaev (1973), with = 0.03. The disc model is simplified and important features, such as energy exchanges, may influence the process of planetary formation andmigration. However, it is a good initial model for a consistent test of the implemented model of planetary formation, which has an known analysical result. More complex cases will be explored in future work. With the newly implemented model for planetary formation, it was possible to simul- taneously study the planet formation and the planet migration using the hydrodynamic simulator. That is, we analyzed both the timescale for planetary formation and the timescale for the migration of the planet, and compared them for the parameters of the model. The analysis revealed that, for our disc model, the timescale of the growth rate of the planet remained lower than the migration timescale, even when the planet crossed the ice line, where there is less material available for solid accretion. Thus, for small planetesimals (1km radius) it was possible to obtain planets with masses of approximately 5 Jupiter masses in regions between 0.5 and 1 au, in nearly the same time as the lifetime of the disc. It is worth noting that this thesis presents a detailed description of how to implement the model for planetary formation in the FARGO3D, including an appendix with the commented code. The goal is to allow the reader to use this planet formation model to obtain new results both about the formation of exoplanetary systems and our Solar System, as well as use it in any relevant application.

O método de Floquet foi utilizado para estudar a transição da esteira de dois cilindros posicionados lado a lado. Quando os cilindros estão afastados, cada cilindro possui sua própria esteira e para espaçamentos grandes (T/D > 4) a principal influência do cilindro ao lado é a sincronização das esteiras em anti-fase. A esteira em anti-fase corresponde a um escoamento simétrico em relação à linha central, igualmente espaçada em relação aos dois cilindros. Para espaçamentos com T/D < 3, a esteira em fase visualizada por Williamson (1985) é observada. A análise de Floquet da esteira em anti-fase simétrica encontrou um modo que quebra a simetria e induz a transição para esteira em fase. Reduzindo o espaçamento diversos modos complexos apresentam multiplicadores de Floquet que crescem e se tornam dominantes para T/D = 2 coincidindo com o surgimento de esteira irregular. A aproximação dos cilindros também afeta o surgimento de tridimensionalidades no escoamento. Os modos A e B de Williamson (1996b) observados para o cilindro isolado ainda existem, mas observa-se uma supressão do modo B. Por outro lado, o modo A se torna instável para Re menores. A esteira em fase também apresenta os modos A e B, mas neste caso, o modo B se torna instável para Re menores que o observado por Williamson. / The Floquet method was used to study the transition in the wake of two side-by-side circular cylinders. When the cylinders are far apart, each cylinder presents its own wake and for large spacing (T/D > 4) the main influence from the neighboring cylinder is an anti-phase synchronization of the wakes. The antiphase wake corresponds to a symmetric flow in relation to the mid-line between cylinders. When T/D < 3 the in-phase wake described by Williamson (1985) is also observed. The Floquet analysis of the symmetric anti-phase wake found an unstable mode that breaks the symmetry and triggers the transition to in-phase vortex-shedding. As the spacing is further reduced, several complex modes have Floquet multipliers that grow with the decreasing spacing and when T/D = 2 they become dominant suggesting an important role on the irregular wake regime. The presence of the neighboring cylinder also affects the transition to three-dimensional wake. Modes A and B described by Williamson (1996b) for the isolated circular cylinder are still observed but mode B is suppressed as the spacing decreases. On the other hand, mode A becomes unstable for lower Re numbers. The in-phase wake also presents modes A and B but in this case, mode B becomes unstable for lower Re numbers when compared to the single circular cylinder.

Cette thèse consiste en l’étude expérimentale de l’érosion d’un milieu granulaire horizontal par un jet vertical. Dans un premier temps, nous étudions finement le seuil d’érosion. L’injecteur est placé à une distance donnée de l’empilement, et la vitesse débitante du jet est progressivement augmentée jusqu’à l’observation du déplacement des premiers grains à la surface du sédiment. La variation de la distance pour la mesure du seuil conduit le jet à passer par différents régimes d’écoulement, notamment laminaire et turbulent. Une analyse est menée à partir des modèles auto-similaires des jets en régimes laminaire et turbulent, qui prévoient une décroissance de la vitesse axiale en fonction de la distance au point source de l’écoulement appelé origine virtuelle. Il est alors possible d’estimer la vitesse locale au niveau de l’empilement, ce qui permet de montrer que le mécanisme local d’érosion décrit par le nombre de Shields est inertiel et indépendant du régime du jet. Dans un second temps, nous menons une étude sur la morphologie des cratères formés au-delà du seuil d’érosion. A nombre de Shields inertiel croissant, le cratère passe d’une forme entièrement parabolique à une forme plus complexe, composée d’une partie parabolique invariante à l’aplomb du jet et d’une couronne avalancheuse de pente constante sur les flancs. Nous montrons que l’épaisseur de l’empilement n’a pas d’influence sur les caractéristiques des cratères tant que le jet n’atteint pas le support. Lorsque c’est le cas, nous observons alors une troisième forme de cratère composée d’une région centrale sans grains et conservant une partie avalancheuse sur les flancs, raccordée au support par une petite zone parabolique. Nous montrons enfin que les caractéristiques du cratère sont contrôlées par la distance jet-empilement et qu’il est nécessaire de tenir compte de l’écart du nombre de Shields à sa valeur seuil dans cette analyse en fonction de la distance. / The present thesis consists in the experimental study of the erosion of a horizontal granular bed by a vertical jet. In a first part we study in details the erosion threshold. With the injector fixed at a given distance from the granular surface, the mean jet velocity is gradually increased until the displacement of first grains at the bed surface. Depending on the jet-bed distance, different jet flow regimes are observed, from laminar to turbulent. Using self-similar jet models in either laminar or turbulent regimes, which predict the axial velocity decay as a function of the distance from a flow point source called virtual origin, the local velocity at the bed position is estimated, allowing us to show that the local erosion mechanism described by the Shields number is inertial and independent of the jet regime. In a second part, we study the shape of craters formed above erosion threshold. Increasing the Shields number, the crater goes from a shape entirely parabolic to a more complex one with an invariant parabolic region close to the jet axis and a constant avalanching slope further on the side. We show that the bed thickness has no influence on the crater characteristics as long as the jet does not reach the bottom wall. When it does, we observe a third shape for the crater composed of a central flat region without any grains connected to the avalanching crown on the side by a small parabolic crown. We show the crater characteristics are governed by the jet-bed distance and that it is necessary to take into account the difference between the Shields number and its threshold value in this distance analysis.

Este trabalho aborda a influência da hidrodinâmica da Lagoa dos Patos (RS) no comportamento de variáveis indicadoras da qualidade da água, como o material em suspensão, o oxigênio dissolvido, os nutrientes inorgânicos dissolvidos e a clorofila-a. Adicionalmente, o trabalho apresenta uma avaliação do efeito do lançamento de efluentes na magnitude das concentrações destas variáveis e nas suas inter-relações. Para o desenvolvimento deste estudo aplicou-se o modelo numérico MOHID 2D, utilizado com êxito na gestão ambiental de regiões costeiras. Os resultados indicam que a Lagoa dos Patos é um corpo lagunar heterogêneo no qual sua hidrodinâmica é regida principalmente pela atuação dos ventos e da vazão fluvial. Esses fatores influenciam diretamente o comportamento das variáveis estudadas. A presença de efluentes altera significativamente a magnitude das concentrações dos nutrientes e da clorofila-a no ambiente, principalmente nas regiões próximas aos locais de lançamento. A modelagem numérica é uma importante ferramenta para a gestão ambiental de sistemas dinâmicos e que variáveis ecológicas são condicionadas pelas suas inter-relações e pela circulação do sistema. / This work assesses the influence of Patos Lagoon- RS hydrodynamics in the behavior of water quality indicator variables as like suspended material, dissolved oxygen, dissolved inorganic nutrients and chlorophyll-a. Also gives an assessment of the effect of effluent discharge in the magnitude of the concentrations of these variables and in their interrelationships. To develop this study we applied the numerical model MOHID 2D, successfully applied in environmental management of coastal areas. The results indicate that Patos Lagoon is a heterogeneous system in which its hydrodynamic is governed mainly by the action of wind and river flow, which directly influence the behavior of water quality variables. Furthermore, the presence of effluent significantly changes the magnitude of the nutrients and chlorophyll-a concentration, particularly in areas close to the sewage launch sites. We concluded that the numerical modeling is an important tool for the dynamics systems management and that ecological variables are not only conditioned by their interrelations, but also by system circulation.

No / Two numerical particle models, the Smoothed Particle Hydrodynamics (SPH) and Moving Particle Semi-implicit (MPS) methods, coupled with a sub-particle scale (SPS) turbulence model, are presented to simulate free surface flows. Both SPH and MPS methods have the advantages in that the governing Navier¿Stokes equations are solved by Lagrangian approach and no grid is needed in the computation. Thus the free surface can be easily and accurately tracked by particles without numerical diffusion. In this paper different particle interaction models for SPH and MPS methods are summarized and compared. The robustness of two models is validated through experimental data of a dam-break flow. In addition, a series of numerical runs are carried out to investigate the order of convergence of the models with regard to the time step and particle spacing. Finally the efficiency of the incorporated SPS model is further demonstrated by the computed turbulence patterns from a breaking wave. It is shown that both SPH and MPS models provide a useful tool for simulating free surface flows

abstract: Chiral symmetry and its anomalous and spontaneous breaking play an important role in particle physics, where it explains the origin of pion and hadron mass hierarchy among other things. Despite its microscopic origin chirality may also lead to observable effects in macroscopic physical systems -- relativistic plasmas made of chiral (spin-$\frac{1}{2}$) particles. Such plasmas are called \textit{chiral}. The effects include non-dissipative currents in external fields that could be present even in quasi-equilibrium, such as the chiral magnetic (CME) and separation (CSE) effects, as well as a number of inherently chiral collective modes called the chiral magnetic (CMW) and vortical (CVW) waves. Applications of chiral plasmas are truly interdisciplinary, ranging from hot plasma filling the early Universe, to dense matter in neutron stars, to electronic band structures in Dirac and Weyl semimetals, to quark-gluon plasma produced in heavy-ion collisions. The main focus of this dissertation is a search for traces of chiral physics in the spectrum of collective modes in chiral plasmas. I start from relativistic chiral kinetic theory and derive first- and second-order chiral hydrodynamics. Then I establish key features of an equilibrium state that describes many physical chiral systems and use it to find the full spectrum of collective modes in high-temperature and high-density cases. Finally, I consider in detail the fate of the two inherently chiral waves, namely the CMW and the CVW, and determine their detection prospects. The main results of this dissertation are the formulation of a fully covariant dissipative chiral hydrodynamics and the calculation of the spectrum of collective modes in chiral plasmas. It is found that the dissipative effects and dynamical electromagnetism play an important role in most cases. In particular, it is found that both the CMW and the CVW are heavily damped by the usual Ohmic dissipation in charged plasmas and the diffusion effects in neutral plasmas. These findings prompt a search for new physical observables in heavy-ion collisions, as well as a revision of potential applications of chiral theories in cosmology and solid-state physics. / Dissertation/Thesis / Doctoral Dissertation Physics 2019

La simulation numérique des éoliennes flottantes est essentielle pour le développement des Energies Marines Renouvelables. Les outils de simulation classiquement utilisés supposent un écoulement stationnaire sur les rotors. Ces théories sont généralement assez précises pour calculer les forces aérodynamiques et dimensionner les éoliennes fixes (à terre ou en mer) mais les mouvements de la plateforme d’une éolienne flottante peuvent induire des effets instationnaires conséquents. Ceux-ci peuvent par exemple impacter la force de poussée sur le rotor. Cette thèse de doctorat cherche à comprendre et à quantifier les effets de l’aérodynamique instationnaire sur la tenue à la mer des éoliennes flottantes, dans différentes conditions de fonctionnement. L’étude montre que les forces aérodynamiques instationnaires impactent les mouvements de la plateforme lorsque le rotor est fortement chargé. Les modèles quasi-stationnaires arrivent néanmoins à capturer la dynamique des éoliennes flottantes avec une précision suffisante pour des phases de design amont. Les éoliennes flottantes à axe vertical sont elles aussi étudiées pour des projets offshore puisqu’elles pourraient nécessiter des coûts d’infrastructure réduits. Après avoir étudié l’influence de l’aérodynamique instationnaire sur la tenue à la mer de ces éoliennes, une comparaison est menée entre éoliennes flottantes à axe horizontal et à axe vertical. Cette dernière subit une importante poussée aérodynamique par vents forts, induisant de très grands déplacements et chargements. / Accurate numerical simulation of thesea keeping of Floating Wind turbines (FWTs) is essential for the development of Marine Renewable Energy. State-of-the-art simulation tools assume a steady flow on the rotor. The accuracy of such models has been proven for bottom-fixed turbines, but has not been demonstrated yet for FWTs with substantial platform motions. This PhD thesis focuses on the impact of unsteady aerodynamics on the seakeeping of FWTs. This study is done by comparing quasi-steady to fully unsteady models with a coupled hydro-aerodynamic simulation tool. It shows that unsteady load shave a substantial effect on the platform motion when the rotor is highly loaded. The choice of a numerical model for example induces differences in tower base bending moments. The study also shows that state of the art quasi-steady aerodynamic models can show rather good accuracy when studying the global motion of the FWTs. Vertical Axis Wind Turbines (VAWTs) could lower infrastructure costs and are hence studied today for offshore wind projects. Unsteady aerodynamics for floating VAWT sand its effects on the sea keeping modelling have been studied during the PhD thesis,leading to similar conclusions than for traditional floating Horizontal Axis Wind Turbines (HAWTs). Those turbines have been compared to HAWTs. The study concludes that, without blade pitch control strategy, VAWTs suffer from very high wind thrust at over-rated wind speeds, leading to excessive displacements and loads. More developments are hence needed to improve the performance of such floating systems.

Les étoiles de masse intermédiaire (2M⊙ ≤ M ≤ 10M⊙) sont parmi les sources dominantes du champ interstellaire FUV dans la Galaxie. Elles régulent les phases du milieu interstellaire et l’ensemble des processus de formation stellaire galactique. Alors que les protoétoiles de type solaire et massives ont été et continuent à faire l’objet de nombreuses études, la formation des étoiles intermédiaires a été relativement peu étudiée. Leur structure physique, composition chimique et leur richesse moléculaire sont un domaine à explorer.L’objectif de ma thèse est d’obtenir un recensement détaillé et aussi complète que possible des propriétés physico-chimiques d’une protoétoile isolée de masse intermédiaire. Notre choix s’est porté sur Cep E-mm (100 L⊙).J’ai pour cela complété un relevé spectral de l’émission moléculaire dans les bandes (sub)millimétriques entre 72 et 350 GHz avec le télescope de 30m de l’IRAM. La sensibilité des observations a permis d’identifier la présence de nombreuses molécules complexes organiques (COMs) dans l’enveloppe de la protoétoile, mais aussi, plusieurs espèces moléculaires inhabituelles dans le jet généré par la protoétoile. Des observations complémentaires avec le télescope de 30m ont permis de cartographier l’émission moléculaire à grande échelle (20’’ à 11’’ ; 15000 à 8000 UA). En parallèle, des cartes interférométriques de l’émission moléculaire entre 86 – 90 GHz et 216 – 220 GHz ont été obtenues avec l’interféromètre de l’IRAM (NOEMA) à 1.4’’ (1000 UA) de résolution angulaire. Ces observations m’ont permis d’obtenir une première description de la distribution de l’émission moléculaire au sein de l’enveloppe, des grandes échelles, dans les parties extérieures de l’enveloppe étendue, aux petites échelles dans la région d’un hot corino. Les études présentées ici ont suivi un travail méticuleux de réduction et d’analyse des données, single-dish et interférométriques. Plus précisément, j’ai identifié et séparé les contributions à l’émission détectée dans le lobe du télescope de 30m de l’IRAM des différentes régions physiques du cœur protostellaire. De ce fait, j’ai identifié et caractérisé quatre composantes physiques qui diffèrent par leurs propriétés spectroscopiques et leurs conditions d’excitation : l’enveloppe étendue, le hot corino, le flot bipolaire basse vitesse et le jet à haute vitesse. Enfin, l’anisotropie de la distribution de brillance du flot et du jet bipolaire ne peut pas être modélisée par l’approche ‘’classique’’ d’une source gaussienne. J’ai développé des outils spécifiques semi-analytiques pour calculer de manière approchée, et plus raisonnable, le couplage entre le lobe du télescope et la source. / Intermediate-mass stars (2 M⊙ ≤ M ≤ 10 M⊙) are among the dominant sources of FUV interstellar field in the Galaxy. They regulate the phases of interstellar medium and the whole process of galactic star formation. While solar-type and massive protostars have been and continue to be the subject of many studies, the formation of intermediate stars has been relatively little studied. Their physical structure, chemical composition and molecular richness are still a subject to explore.The aim of my thesis is to obtain a detailed census, as complete as possible ,of the physical and chemical structure of an isolated intermediate-mass protostar: Cep E-mm (100 L⊙).I have completed a spectral survey of the molecular emission in the (sub)millimetre bands between 72 and 350 GHz with IRAM 30m telescope. The sensitivity of the observations made it possible to identify the presence of numerous complex organic molecules (COMs) in the protostar envelope, but also several unusual molecular species in the protostellar jet. Additionally, further observations with the IRAM 30m telescope made it possible to map the molecular emission at large scale (20’’ to 11’’; 15000 to 8000 AU). In parallel, interferometric maps of the molecular emission between 86 – 90 GHz and 216 – 220 GHz were obtained with NOEMA, the IRAM interferometer, at 1.4’’ (1000 AU) of angular resolution. These observations allowed me to obtain the distribution of molecular emission within the source, from large scales in the outer parts of the extended envelope, to the small scales in the hot corino region. The single-dish and interferometric observations were reduced and analysed in a meticulous manner. More precisely, I identified and separated the molecular emission contribution from the different physical regions as observed with the IRAM 30m telescope. I have identified and characterized fours physical components that differ in their spectroscopic properties and excitation conditions: the extended envelope, the hot corino, the bipolar outflow and the high-velocity jet. Finally, the anisotropy of the brightness distribution from the outflow system cannot be modelled by the “classical” Gaussian approach. I have developed specific tools to estimate, in a semi-analytical manner, the coupling between the telescope lobe and the source.

This thesis is an attempt to create a computer based tool that can be used academically and later industrially by naval architects in analysis and development of efficient planing hull forms. The work contained here is based on the theory created by Vorus (1996) which falls between empirical asymptotic solutions and intractable non-linear boundary value problem in the time-domain. The computer code developed predicts pressures on the bottom of high-speed planing craft during slamming events. The code is validated with available numerical data as a benchmark case. An aluminum wedge is dropped from various heights resulting in unsteady pressure distributions with high peak over the bottom plate. These pressure distributions are compared to the numerically predicted pressures by the code and presented in this thesis. The predicted flow velocities are within 8% difference of experimental data. The graphs depicts similar trends in experimental and numerical data. The predicted peak pressures deviate within 4% to 20% from experimental data. The analysis and comparison illustrate efficacy of the code.

CE-QUAL-W2 is a 2-D hydrodynamic and water quality model that has been applied to reservoirs, lakes, river systems, and estuaries throughout the world. However, when this model is applied for shallow systems, this model requires a long calculation time to maintain numerical stability, compared to applications of reservoirs or deeper river systems. To solve this problem, a new hydrodynamic and temperature model was built based on the framework of CE-QUAL-W2 but that allows for steady-state hydrodynamic computations. By calculating the hydrodynamics at steady-state, the time step for stability is relaxed and simulations can proceed at much higher time steps. The rest of the model framework is still used for water quality state variables, in this case, temperature. The algorithm used for computing the water surface elevation is Manning's equation. This thesis study is one part of the Willamette Water 2100 project (Santelmann et al., 2012), which examines hydrological, ecological, and human factors affecting water scarcity in the Willamette River Basin. This study included three stages: (1) Convert six existing CE-QUAL-W2 V3.1 models into a newer version: CE-QUAL-W2 V3.7. (2) Develop the steady-state model code in FORTRAN. (3) Test the steady-state model on three river systems in the Willamette River Basin at Year 2001 and 2002. The result proved that the steady-state model could reduce the computing time by 90% for river applications, while predicting dynamic river temperature with high accuracy at a two-minute time scale. This new model will be employed to simulate the future of the Willamette River System at a decadal or centennial timescales, addressing river temperature concerns and fish habitat issues.