Over the last forty or so years interest in the study of wing-tip vortices has increased, primarily due to the introduction of larger passenger aircraft and their subsequent interaction with smaller aircraft. The vortices generated by these larger aircraft present a problem in two main areas; the wake hazard problem, where other aircraft can be subjected to the large tangential velocities of the vortex, and the interaction with ground based features of vortices created during landing and take-off. The first of these is particularly dangerous close to the ground when aircraft are in a high lift configuration at take-off and landing. As the vortices effectively scale with aircraft wing span, significant encounters between large vortices and smaller aircraft have been documented over the years. An example of one such documented wake vortex interaction incident can be found in Ogawa. In this study, the system of vortices are described as classical Batchelor vortices (or linear superpositions thereof) which are then subjected to small perturbations. By discretising the domain and solving for the eigenvalues of the system it is possible to ascertain the stability characteristics of the flow as a function of the system parameters which include the axial wave-number, the spacing of the vortices, their cross-flow decay rate and their axial strength. We first consider the inviscid instability of multiple tip vortices, an approximation which is valid in the limit of large Reynolds numbers. In this limit the stability of the flow is dominated by the axial component of the basic vortex flow. The governing equations of continuity and momentum are reduced to a second order partial differential equation (PDE). This equation is solved numerically to determine which vortex configurations produce the greatest instability growth rate. These results are extended to consider the effect of compressibility on the inviscid instability. Finally we consider the effects of viscosity on the stability of the full Batchelor similarity solution which results in a second order PDE in four dependent variables. The stability equations are solved both globally (for the entire eigenspectra) and locally (for a single eigenvalue in a pre-determined region) using codes that run in both serial and parallel form. The numerical methods are based on pseudospectral discretisation (Chebyshev polynomials for Cartesian and radial directions and Fourier for azimuthal) in the global scheme, the eigenvalues being recovered either with a QZ algorithm or a shift-and-invert Arnoldi algorithm. For the local scheme, fourth order centred finite-diffences are used in conjunction with an iterative eigenvalue recovery method. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1383207 / Thesis (Ph.D.) - University of Adelaide, School of Mathematical Sciences, 2010

Over the last forty or so years interest in the study of wing-tip vortices has increased, primarily due to the introduction of larger passenger aircraft and their subsequent interaction with smaller aircraft. The vortices generated by these larger aircraft present a problem in two main areas; the wake hazard problem, where other aircraft can be subjected to the large tangential velocities of the vortex, and the interaction with ground based features of vortices created during landing and take-off. The first of these is particularly dangerous close to the ground when aircraft are in a high lift configuration at take-off and landing. As the vortices effectively scale with aircraft wing span, significant encounters between large vortices and smaller aircraft have been documented over the years. An example of one such documented wake vortex interaction incident can be found in Ogawa. In this study, the system of vortices are described as classical Batchelor vortices (or linear superpositions thereof) which are then subjected to small perturbations. By discretising the domain and solving for the eigenvalues of the system it is possible to ascertain the stability characteristics of the flow as a function of the system parameters which include the axial wave-number, the spacing of the vortices, their cross-flow decay rate and their axial strength. We first consider the inviscid instability of multiple tip vortices, an approximation which is valid in the limit of large Reynolds numbers. In this limit the stability of the flow is dominated by the axial component of the basic vortex flow. The governing equations of continuity and momentum are reduced to a second order partial differential equation (PDE). This equation is solved numerically to determine which vortex configurations produce the greatest instability growth rate. These results are extended to consider the effect of compressibility on the inviscid instability. Finally we consider the effects of viscosity on the stability of the full Batchelor similarity solution which results in a second order PDE in four dependent variables. The stability equations are solved both globally (for the entire eigenspectra) and locally (for a single eigenvalue in a pre-determined region) using codes that run in both serial and parallel form. The numerical methods are based on pseudospectral discretisation (Chebyshev polynomials for Cartesian and radial directions and Fourier for azimuthal) in the global scheme, the eigenvalues being recovered either with a QZ algorithm or a shift-and-invert Arnoldi algorithm. For the local scheme, fourth order centred finite-diffences are used in conjunction with an iterative eigenvalue recovery method. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1383207 / Thesis (Ph.D.) - University of Adelaide, School of Mathematical Sciences, 2010

[Truncated abstract] The subject of fan noise generating mechanisms and its control has been studied intensively over the past few decades as a result of the ever-increasing demand for more powerful fans. A unique feature of fan noise is that it consists of high-level discrete frequency noise related to the blade passing frequency, and low-level broadband noise due mostly to turbulent airflow around the fan. Of the two types of fan noise, the discrete frequency noise is the more psychologically annoying component. Past research into fan noise has shown that the discrete frequency fan noise are dipole in nature and are caused predominantly by the fluctuating lift acting on the surfaces of the fan blades. Based on this, several theoretical models have been established to correlate these fluctuating lift forces to the far-field sound pressure. However, one general assumption in these models is that the fan blades are assumed rigid, and the consequence of such an assumption is that it is unclear if the far-field sound pressure is caused solely by the aerodynamic lift force, or whether the blade vibration also plays a substantial role in the generation of the far-field fan noise. One of the goal of this thesis was thus to experimentally quantify the contribution of blade vibration to far-field fan noise and it was found that blade vibration, whilst coherent with the far-field fan noise, did not contribute significantly. Aside of this, several experiments aimed at filling knowledge gaps in the understanding of fan noise characteristics were also be conducted, in particular, to understand the relationship between far-field sound pressure level to blade lengths as well as the number of blades on the fan. The experiments showed that for fans with many blades, the dependency of the far-field sound pressure on blade length is stronger than fans with less blades. Furthermore, dipole measurements showed that the dipole characteristics of fan noise does not occur only at the discrete frequencies, but also within a range of broadband frequencies, implying that the source for both discrete and broadband is the same. The second section of this thesis deals with the study of vortex shedding and its active control. When a circular cylinder (or any object) is placed in a flow within a specified Reynolds number range, flow separation and periodical wake motion is formed behind the cylinder, which is known as vortex shedding. It has been found in previous research that this wake motion is affected by acoustic field imposed on it via loudspeakers. This suggests that there is a strong acoustic-vortex relationship. However, little of this relationship is understood as conventional methods of studying vortex centre around the use of hot-wire anemometry, which effectively measures the velocity fluctuation in the flow. This thesis is the first in using a microphone to study the acoustic characteristic of the vortex wake, and experimental results shows that the two parallel shear layers of the wake carry the strongest pressure signals at the vortex shedding frequency, whilst the entrapped region between the layers carries the strongest pressure signals at the first harmonic.

In dieser Arbeit werden magnetische Vortex-Dreifachlagen-Systeme untersucht. Mittels Magnetfeld, Strom und Röntgenzirkulardichroismus kann erstmals die magnetische Konfiguration der Vortexlagen mit dem simultan gemessenen Magnetowiderstand verglichen werden. Die senkrecht mit Strom durchflossenen Kobalt-Kupfer-Permalloy Scheiben werden in einem Mehrschrittprozess mittels Elektronenstrahllithographie auf einer Membran hergestellt, um mit Rastertransmissions-Röntgenmikroskopie untersuchbar zu sein. Die Auswertung der STXM-Bilder zeigt das gleiche Verhalten wie die Widerstandsmessungen und erlaubt eine eindeutige Zuordnung. Um auch die kleinsten scheibenförmigen Dreifachlagensysteme mittels ferromagnetischer Resonanz zu messen, wurde die Mikroresonator FMR optimiert. Damit können bereits etwa 2.3*10^7 Kobaltatome gemessen werden, wobei die Empfindlichkeit bis zu 4*10^6 Atomen ausreichend sein sollte. Durch 6-fache Mittelung lässt sich ein Kobaltwürfel mit einer Kantenlänge von 12,5nm detektieren. Dabei sind nicht nur die uniforme Mode, sondern auch lokal angeregte Moden sichtbar. Mittels mikromagnetischer Simulationen lassen sich den Resonanzen Modenbilder zuordnen. Die scheibenförmige Dreifachlage wird mit den FMR-Messungen sowohl mit verringertem Durchmesser, als auch mit reduzierter Zwischenschicht untersucht.

Parmi les différents mécanismes physiques permettant d'actionner des échantillons liquides au sein de labopuces, l'électromouillage sur diélectrique (EWOD) s'impose peu à peu comme une solution fiable permettant de manipuler en particulier des gouttes (labopuces digitaux). Bien que des modèles énergétiques permettent d'expliquer la plupart des fonctions fluidiques élémentaires obtenues par effet EWOD, il demeure certains phénomènes hydrodynamiques en goutte dont la compréhension à l'échelle locale présente des enjeux en termes scientifiques et applicatifs. En particulier, la maîtrise des oscillations de goutte et des écoulements électrohydrodynamiques induits par des signaux électriques alternatifs (AC-EWOD) pourrait permettre l'insertion de nouvelles fonctions dans les labopuces digitaux (brassage, séparation d'espèces). Dans la thèse proposée, une configuration optimale a été retenue consistant en une goutte reposant sur deux électrodes coplanaires passivées. Un banc de caractérisation a été développé ainsi que des logiciels spécifiques dédiés à l'analyse du mouillage et des oscillations de la goutte. Une première étude permet de caractériser l'électromouillage d'une goutte en configuration d'électrodes coplanaires. En particulier, la modélisation des contraintes électriques surfaciques permet de conclure sur leurs rôles dans l'injection normale et tangentielle de quantité de mouvement. Les oscillations de la goutte et les écoulements induits sont ensuite étudiés de manière expérimentale. Suivant la géométrie des électrodes, des configurations d'écoulements axisymétriques et quadripolaires sont observées. Un modèle basé sur le concept de courant de dérive est développé ; sa résolution numérique par éléments finis permet de retrouver les configurations d'écoulement. Des applications biologiques de l'actuation EWOD en signal alternatif sont finalement proposées et discutées pour le développement de laboratoires sur puces. / Among numerous physical mechanisms enabling liquids actuation, electrowetting on dielectric (EWOD) is increasingly considered as a trustful solution enabling discrete iquid sample handling by using electrical fields. Although energetic models can explain most basic fluidic functions, some electrowetting phenomena still remain to be considered as scientific issues. So is the case for droplet oscillations and hydrodynamic flows induced by electrowetting when AC voltage is applied (AC EWOD). The understanding and mastering of these phenomena represent the objectives of this thesis. An open electrode configuration has been used in which the droplet straddles two insulated coplanar electrodes. An experimental setup and dedicated software for the measurement of droplet wetting and droplet oscillations have been developed. A first experimental and numerical study allowed us the characterization of electrowetting in the coplanar electrode configuration. The calculation of the electrical stress distribution delivers criteria which help to conclude about the involvement of tangential electrical stresses in drop convective flow. Then, droplet oscillations and induced flows are experimentally and theoretically investigated. Depending on electrode designs, axisymetrical and quadripolar flows as well can be observed. A model based on steady streaming is implemented and structure flows are numerically reproduced using finite element method. Some practical applications of this research within the framework of lab-on-chips are proposed and discussed.

Les amplifications optimales d'énergie de structures quasiment alignées dans le sens de l'écoulement sont calculées dans le cas d'un sillage parallèle, d'un sillage synthétique faiblement non-parallèle et du sillage d'un cylindre. Il a été observé que de très grandes amplifications d'énergie peuvent être supportés par ces sillages. L'amplification d' énergie s'accroît avec la longueur d'onde des perturbations en envergure à l'exception du sillage du cylindre pour lequel l'accroissement d'énergie est maximal pour λz ≈ 5 − 7 D. Les structures amplifiées de manière optimale sont les streaks fluctuant dans le sens de l’écoulement. Il est montré que ces streaks sont capables de supprimer complètement l'instabilité absolue d'un sillage parallèle lorsqu'ils sont déclenchés avec une amplitude finie. L'instabilité globale d'un sillage faiblement non-parallèle et celle du sillage d'un cylindre peuvent être complètement supprimées par des streaks d'amplitude modeste. L'énergie de contrôle requise pour stabiliser le sillage est très faible lorsque les perturbations optimales sont utilisées, et il est montré qu'elle est toujours plus faible que celle qui devrait être utilisée pour un contrôle uniforme en envergure (2D). Il est aussi montré que la dépendance du taux de croissance est quadratique et que, par conséquent, les classiques analyses de sensibilité au premier ordre ne permettent pas de prédire la grande efficacité de la technique de contrôle par streaks. La dernière partie de ce travail livre des résultats préliminaires sur l'étude expérimentale du contrôle par streaks dans le cas du sillage turbulent d'un corps 3D. Il est montré que les streaks forcés artificiellement dans la zone d'instabilité absolue de l'écoulement sont capables de modifier la dynamique du sillage. / We compute optimal energy growths leading to streamwise streaks in parallel, weakly non-parallel and the circular cylinder wakes. We find that very large energy amplifications can be sustained by these wakes. The energy amplifications increase with the spanwise wavelength of the perturbations except in the circular cylinder wake where maximum energy growths are reached for λz ≈ 5 − 7 D. The optimally amplified structures are streamwise streaks. When forced with finite amplitudes these streaks are shown, in parallel wakes, to be able to completely suppress the absolute instability. The global instability of the weakly non-parallel and the circular cylinder wakes can be completely suppressed with moderate streaks amplitudes. The energy required to stabilize the wake is much reduced when optimal perturbations are used, and it is shown to be always smaller than the one that would be required if a 2D control was used. It is also shown that the sensitivity of the global mode growth rate is quadratic and that therefore usual first order sensitivity analyses are unable to predict the high efficiency of the control-by-streaks strategy.

La recherche de nouveaux matériaux absorbant les ondes électromagnétiques dans le domaine des hyperfréquences est devenue un enjeu majeur avec le développement croissant des moyens de communication et, corrélativement, le besoin de se prémunir efficacement contre la « pollution » électromagnétique (protection des équipements et des personnes). Dans ce manuscrit, nous nous intéressons à un matériau composite anisotrope constitué d'une matrice polymère chargée en particules ferromagnétiques aplaties appelées pétales. Ce type de composite suscite actuellement un intérêt grandissant dans la communauté grâce aux nombreux avantages qu'il présente (ajustement de la bande d'absorption en fonction de la nature et du rapport de forme des charges, faible épaisseur du revêtement). Le champ de cette étude s'est voulu relativement large afin d'avoir une vue d'ensemble des problématiques liées à ces composites à base de pétales et cela à plusieurs échelles. Dans un premier temps, une étude originale a été menée sur le pétale seul. Après des travaux préliminaires portant sur l'élaboration des pétales et leurs propriétés morphologiques, des caractérisations magnétiques statiques et dynamiques ont été réalisées sur un pétale unique. Le spectre de perméabilité obtenu met en évidence trois résonances. Une étude complémentaire menée sur des objets de mêmes dimensions élaborés par PVD et structurés par FIB a permis, par analogie, d'attribuer ces trois résonances respectivement aux domaines, aux parois et au vortex joignant les parois. Dans un second temps, une étude approfondie a été menée sur le composite complet. L'adaptation de la technique de perméamétrie par perturbation de spire a rendu possible la caractérisation fine et complète de matériaux composites épais avec ou sans champ magnétique statique appliqué et pour différentes directions de pompage. Celle-ci a permis de confirmer l'origine des différentes résonances malgré le désordre structurel caractéristique des milieux composites. Pour finir, une étude à vocation plus applicative a été réalisée établissant le lien fort entre la microstructure (porosité, orientation et taille des particules) et les propriétés électromagnétiques du composite. Le potentiel industriel, tant d'un point de vue de l'élaboration que des performances, a pu être démontré. / Research on new microwave absorbing materials has become a major issue with the growing development of wireless communications and, accordingly, the need to shield effectively from the electromagnetic "pollution" (protection of equipment and persons).In this manuscript, we focus on an anisotropic composite consisting of aligned ferromagnetic flakes embedded in a nonmagnetic matrix. There is currently a growing interest for this kind of composite in the community due to the many benefits it provides (adjustment of the absorption band as a function of both nature and flakes aspect ratio, thin composite coating). The scope of this study was deliberately relatively large in order to get an overview of issues related to these flakes composites at several scales. At first, an original study was conducted on a single flake. After preliminary work on the development of flakes and their morphological properties, static and dynamic magnetic characterizations were performed on a single flake. The permeability spectrum obtained shows three resonances. A complementary study on objects of the same size, produced by PVD and structured by FIB has, by analogy, attributed these three resonances to respectively, domains, domains wall and an embedded vortex (vortex linked with several domains walls).In a second step, the evolution of the shorted microstrip permeametry technique made possible the detailed and complete characterization of thick composites with or without a static magnetic field applied in different directions and for various pumping directions. This confirmed the origin of the different resonances despite the characteristic structural disorder of composite media.Finally, an applicative study was conducted establishing the strong link between the microstructure (porosity, particle size and orientation) and the electromagnetic properties of the composite. Taking into consideration both elaboration and performance point of views, the industrial potential of this composite has been demonstrated.

Sotalia guianensis é um pequeno cetáceo costeiro encontrado ao longo do Oceano Atlântico Sul-Ocidental. Está exposta a inúmeras ameaças, tais como captura acidental em redes de pesca, tráfego de embarcações e turismo. A análise de viabilidade populacional (AVP) é uma forma de prever as flutuações e a probabilidade de persistência ou extinção de uma espécie ou população ao longo do tempo, incorporando dados demográficos, ecológicos e ambientais de populações reais em simulações computacionais de modelos estocásticos e determinísticos. O presente estudo teve como objetivos estimar densidade, abundância e realizar uma AVP para S. guianensis no Complexo Estuarino-Lagunar de Cananéia, São Paulo. Estimativas de abundância e densidade foram obtidas entre 2011 e 2012, utilizando o método de transecção linear com amostragem de distâncias, com 1.339,91 km percorridos e 83h05min em esforço. Avistou-se 241 grupos, compostos por 1 a 20 indivíduos. O programa Distance, com modelo half-normal e ajuste coseno e menor valor de AIC, estimou uma abundância de 193 indivíduos (95%IC: 158 - 237) e densidade de 2,5538 ind/km2 (95%IC: 2,0812 - 3,1337). A média de tamanho de grupo é 4,1504 indivíduos (95%IC: 3,7666 - 4,5734). De forma geral, a espécie apresenta grandes variações ao longo de sua distribuição com relação ao tamanho populacional, densidade, tamanho de grupos, distribuição nos habitats e residência. Tais diferenças estão associadas possivelmente às características físicas e ambientais de cada habitat, que interferem direta ou indiretamente na distribuição e dinâmica populacional da espécie e suas presas. Para a AVP a população foi tratada como não suplementada, sem dispersão, sem remoção, sem depressão endogâmica e a extinção foi definida como a permanência de apenas um sexo. O valor inicial da população é 193 indivíduos e demais parâmetros demográficos e reprodutivos foram estimados com base na literatura disponível. Variações de parâmetros específicos (mortalidade, capacidade de suporte do ambiente (K), variação ambiental na reprodução e catástrofe) foram inseridas nos cenários para avaliar as tendências populacionais sob diferentes ameças. Utilizou-se o programa VORTEX 9.99b. A AVP apontou para o declínio e extinção (P(E) = 1,000) da população em menos de 300 anos em todos os cenários, com taxas de crescimento de -0,082 (SD = 0,120), - 0,049 (SD = 0,107) e -0,086 (SD = 0,062), para os cenários 1, 2 e 3 respectivamente. O tempo médio para extinção foi estimado em 39,6 anos para o cenário 1, 57,3 anos para o cenário 2 e 3,3 anos para o cenário 3. As projeções geradas pela AVP apontaram cenários pessimistas, o que pode estar relacionado ao pequeno tamanho da população. As análises mostram que variações no tamanho populacional, mortalidade, K e catástrofes podem influenciar fortemente a persistência de pequenas populações. O estuário de Cananéia é um ambiente favorável e bem preservado que oferece recursos suficientes para S. guianensis, entretanto, o aumento das atividades antrópicas na área pode levar a mudanças na dinâmica populacional e alterações no habitat, comprometendo sua persistência ao longo do tempo. / Sotalia guianensis is a small coastal cetacean found along the south-western Atlantic Ocean. Through its range, is exposed to numerous threats, such as bycatch in fishing nets, vessel traffic and tourism. Population viability analysis (PVA) is a way to predict the trends and the probability of persistence or extinction of a species or population over time, incorporating demographic, ecological and environmental data of real populations in computer simulations of stochastic and deterministic models. The present study aimed to estimate density, abundance and population viability of S. guianensis in the estuarine-lagoon complex. Estimates of abundance and density were obtained between 2011 and 2012, using the distance sampling method and linear transects, with 1,339 .91 km and 83h05min in effort. It were recorded 241 groups (n) with group size between 1 to 20 individuals. The Distance program, with half-normal model and adjust cosine with the lowest AIC, estimated an abundance of 193 individuals (95% CI: 158-237) and density of 2.5538 ind/km2 (95% CI: 2.0812 - 3.1337). The average group size is 4.1504 individuals (95% IC: 3.7666-4.5734). In general, the species presents large variations throughout its distribution regarding population size, density, groups size, distribution in habitat and residence. Such differences are possibly associated with the physical characteristics of each habitat and environmental conditions that interfere directly or indirectly in the distribution and population dynamics of the species and its prey. For the PVA population was treated as not supplemented, without dispersion, without removal, without inbreeding depression, and extinction was defined as the presence of only one sex. The initial population size was 193 individuals and other demographic and reproductive parameters were estimated based on available literature for the species. Variations of specific parameters (mortality, carrying capacity of the environment, environmental variation on reproduction and catastrophe) were used to evaluate population trends under different threats and scenarios. It was used the VORTEX program v. 9.99 b. AVP pointed to the decline and extinction (P(E) = 1,000) of the population in less than 300 years in all scenarios, with growth rates of -0.082 (SD = 0.120), -0.049 (SD = 0.107) and - 0.086 (SD = 0.062), for scenarios 1, 2 and 3 respectively. The average time to extinction was estimated at 39.6 years for scenario 1, 57.3 years for scenario 2 and 3.3 years for scenario 3. The projections generated by the AVP showed pessimistic scenarios, which may be related to the small size of the population. The analyses show that variations in population size, mortality, carrying capacity and disasters can strongly influence the persistence of small populations. Cananéia estuary is a well preserved environment that offers sufficient resources to S. guianensis, however, the increase in anthropogenic activities in the estuary may lead to changes in population dynamics and habitat quality, compromising their persistence over time.

La zone morte, région laminaire confinée au coeur des disques protoplanétaires dont la turbulence de l'écoulement à petite échelle explique l'accrétion de matière sur l'étoile en formation, semble être un lieu propice à la formation planétaire. En effet, au bord interne de la zone morte la différence d'accrétion entraîne le développement d'une sur-densité capable de piéger les grains de poussière qui dérivent vers l'étoile. L'écoulement à cet endroit est de plus potentiellement instable. Le cas échéant, il s'organise en structures tourbillonnaires appelées ''vortex'' qui collectent efficacement la poussière. La position du bord interne est toutefois très incertaine et dépend en particulier de la thermodynamique du modèle de disque considéré. Récemment, le déplacement du bord interne a été envisagé pour expliquer la variabilité de l'accrétion des étoiles jeunes. Cette thèse aborde le problème posé par l'influence de la thermodynamique sur la dynamique du bord interne de la zone morte. Des simulations MHD qui incluent le couplage entre les processus thermodynamiques avec la dynamique de l'écoulement ont tout d'abord permis de confirmer le comportement dynamique du bord interne ainsi que de réaliser la mesure inédite de sa vitesse typique de déplacement. La comparaison de ces résultats avec les prédictions données par un modèle de champ moyen a révélé le rôle du transport d'énergie par des ondes excitées au bord interne de la zone morte. Ces simulations présentent de plus un phénomène nouveau: les vortex formés à l'interface suivent un cycle de formation-migration-destruction. Cette découverte est susceptible de modifier notre vision du scénario de formation planétaire. En résumé, cette thèse met en évidence le fait que les processus thermodynamiques sont au coeur du fonctionnement de la région du bord interne de la zone morte dans les disques protoplanétaires. / The dead zone, a quiescent region enclosed in the turbulent flow of a protoplanetary disk, seems to be a promising site for planet formation. Indeed, the development of a density maximum at the dead zone inner edge, that has the property to trap the infalling dust, is a natural outcome of the accretion mismatch at this interface. Moreover, the flow here may be unstable and organize itself into vortical structures that efficiently collect dust grains. The inner edge location is however loosely constrained. In particular, it depends on the thermodynamical prescriptions of the disk model that is considered. It has been recently proposed that the inner edge is not static and that the variations of young stars accretion luminosity are the signature of this interface displacements. This thesis address the question of the impact of the gas thermodynamics onto its dynamics around the dead zone inner edge. MHD simulations including the complex interplay between thermodynamical processes and the dynamics confirmed the dynamical behaviour of the inner edge. A first measure of the interface velocity has been realised. This result has been compared to the predictions of a mean field model. It revealed the crucial role of the energy transport by density waves excited at the interface. These simulations also exhibit a new intriguing phenomenon: vortices forming at the interface follow a cycle of formation-migration-destruction. This vortex cycle may compromise the formation of planetesimals at the inner edge. This thesis claims that thermodynamical processes are at the heart of how the region around the dead zone inner edge in protoplanetary disks works.

Dans les supraconducteurs de type II, le champ magnétique pénètre le matériau sous forme de vortex, tourbillon de courants supraconducteurs circulant autour d'un c¿ur normal. Dans les travaux de cette thèse, nous montrons comment le confinement d'un système à une échelle comparable à la longueur de cohérence ? nanométrique modifie sensiblement ses propriétés supraconductrices.Cette étude est menée dans des nanostructures de plomb déposé in-situ sur un substrat de silicium (111), puis mesurées par spectroscopie à effet tunnel, sous UHV, à 300 mK et sous champ magnétique.En confinement extrême (taille latérale D<<10 ?), le système créé des vortex Géants, objets quantiques prédits théoriquement depuis 45 ans. En confinement plus faible (D~10 ?), les vortex peuvent être piégés, s'organisent ensuite en réseau triangulaire d'Abrikosov, puis s'interpénètrent avec le champ magnétique croissant.Les îlots de Pb cristallins supraconducteurs sont reliés entre eux par une monocouche de mouillage de Pb, ici désordonnée et non supraconductrice. Au voisinage des îlots, cette couche acquiert des caractéristiques spectroscopiques spécifiques qui reflètent la supraconductivité induite par proximité et les interactions entre électrons de type Altshuler-Aronov. L'évolution spatiale des spectres tunnel sont simulés en combinant les équations d'Usadel et la théorie du blocage de Coulomb dynamique.En réduisant la distance entre les îlots, l'effet de proximité autour de chacun se recouvre, ce qui forme une jonction Josephson. Sont étudiés finement le nombre, la position, le spectre et la forme des c¿urs de vortex Josephson sous champ magnétique, à travers une grande panoplie de jonctions. / In type II superconductors, the applied magnetic field penetrates the material in quanta of flux called vortices, vortices of superconducting currents circulating around a normal core. In the work of this thesis, we show how the confinement of a system to a scale comparable to the nanometric coherent length ? substantially modifies its superconducting properties.This study is carried out in nanostructures of lead deposited in-situ on a silicon (111) substrate, then studied by scanning tunneling spectroscopy, under UHV, at 300 mK, and under magnetic field. In extremely confinement (lateral size D<<10 ?), systems create Giant vortices, quantum objects predicted 45 years ago. In the weakly confinement (D~10 ?), vortices may be pinned, then are organized in the triangular Abrikosov lattice, finally interpenetrate in surface superconductivity with the increasing magnetic field. Crystalline superconducting Pb islands are here connected by a disordered non-superconducting wetting layer of Pb. In the vicinity of each superconducting island, the wetting layer acquires specific tunnelling characteristics which reflect the interplay between the proximity induced superconductivity and the inherent electron correlations of this ultimate diffusive two-dimensional metal. Spatial evolution of the tunnel spectra are simulated by combining the Usadel equations and the theory of dynamic Coulomb blockade. With reducing the distance between the islands, the proximity effect around each overlaps and forms a Josephson junction. Thanks to the tunneling spectroscopy, number, position, the spectrum and the form of Josephson vortex cores are studied in detail for a large variety of junctions.