A study of the use of solution adaptive grid (SAG) method for simulations of incompressible flows is carried out in this work. Both laminar and turbulent types of flows are chosen. Investigation on laminar flow simulation starts with mesh adaptation criteria that are based on strong changes of some selected flow parameters; pressure and velocity components. Three most common laminar types of flows are studied; flow in a circular pipe, flow in a channel with sudden expansion and flow in a cavity with a moving lid. It is found that with the use of SAG, a reduction in both computational grid nodes and CPU time can be obtained when compared to those of fixed grid while satisfactory solutions are also achievable. Nevertheless, the refinement criteria setup procedure reveals inconveniences and requirement for several judgments that have to be defined ‘ad hoc’. This hence, makes the refinement criteria dubious for real engineering applications. For the study of turbulent flows with large eddy simulation (LES) and implicit filtering, examination of literature reveals that the lack of connections between the filter width and a physical scale has made LES somewhat unclosed, i.e. in a physical sense. In addition, it is known that numerical and modelling errors are always combined and it is difficult to study each of them separately making the total error magnitude difficult to control. Since both error types are characterised by the grid size, LES users very often find cases where a finer mesh no longer provides better accuracy. An attempt to address this ‘physical’ enclosure property of LES and its complication to implement/setup in FLUENT begins with the construction of a new refinement variable as a function of the Taylor scale. Then a new SAG algorithm is formed. The requirement to satisfy a condition of the selected subgrid scale (SAG) model, the Smagorinsky model, is taken into consideration to minimize the modeling error. The construction of a new refinement algorithm is also aimed to be the key to studying the interaction between the two types of error and could lead to the means of controlling their total magnitude. The validation in terms of its effectiveness, efficiency and reliability of the algorithm are made based on several criteria corresponding to suitability for practical applications. This includes the simplicity to setup/employ, computational affordability, and the accuracy level. For this, two different turbulent flow types that represent different commonly found turbulent phenomena are chosen; plane free jet and the flow over a circular cylinder. The simulations of the two cases were carried out in two dimensions. It is found that there are two key factors that strongly determine the success of the algorithm. The first factor is the Taylor scale definition, with literature only available for the turbulent plane jet study, for which good level of accuracy is expected. Unfortunately, this is not true for the flow over a circular cylinder, indicating a need for further analytical work. The second encountered difficulty results from limited access to software codes, which makes it impossible to implement the proposed scheme. As a result, the algorithm formulation needs be modified with carful judgment. Nevertheless, overall results are in reasonably good agreement with their corresponding experimental data.

Predictive accuracy of the previously developed coupled code for the solution of the time-dependent Navier-Stokes equations in conjunction with the radiative transfer equation was first assessed by applying it to the prediction of thermally radiating, hydrodynamically developed laminar pipe flow for which the numerical solution had been reported in the literature. The effect of radiation on flow and temperature fields was demonstrated for different values of conduction to radiation ratio. It was found that the steady-state temperature predictions of the code agree well with the benchmark solution. In an attempt to test the predictive accuracy of the coupled code for turbulent radiating flows, it was applied to fully developed turbulent flow of a hot gas through a relatively cold pipe and the results were compared with the numerical solution available in the literature. The code was found to mimic the reported steady-state temperature profiles well. Having validated the predictive accuracy of the coupled code for steady, laminar/turbulent, radiating pipe flows, the performance of the code for transient radiating flows was tested by applying it to a test problem involving laminar/turbulent flow of carbon dioxide through a circular pipe for the simulation of simultaneous hydrodynamic and thermal development. The transient solutions for temperature, velocity and radiative energy source term fields were found to demonstrate the physically expected trends. In order to improve the performance of the code, a parallel algorithm of the code was developed and tested against sequential code for speed up and efficiency. It was found that the same results are obtained with a reasonably high speed-up and efficiency.

This thesis addresses aspects of the transport of bubbles and capsules (a thin elastic membrane enclosing a viscous fluid) by means of a viscous flow in complex vessel geometries. It focusses on two related themes: (i) the trapping of air bubbles in a sudden streamwise tube expansion and (ii) the extreme deformation of bubbles and capsules in a localised tube constriction. Air bubbles of different volumes were trapped in a tube with a square cross-section, which contains a sudden streamwise expansion in tube width. The liquid filling the tube was driven by constant volume-flux flow, and experiments were performed in both millimetric and micrometric tubes to identify the range of flow rates for which bubbles could get trapped. The gradients in surface energy generated by the broadening of the bubble into the expansion depend strongly on bubble volume and the expansion length. It is shown that in order for a trapped bubble to release from the expansion, the work of the pressure forces due to flow past the bubble must exceed the change in surface energy required to squeeze into the narrower channel. This criterion for trapping was verified by direct pressure measurements and a capillary static model, which uses three-dimensional Surface Evolver calculations. The extreme deformation of bubbles and capsules was investigated using a localised constriction of the tube width. Both bubbles and capsules were shown to adopt highly contorted configurations and exhibit broadly similar features over a wide range of flow rates, suggesting that the deformation was primarily imposed by the geometry through viscous shear forces. However, bubbles and capsules also display distinguishing features. Bubbles can breakup and exhibit thinning of the rear of the bubble at a critical flow rate, which is associated with a divergence of the rear tip speed and curvature. In contrast, the capsule membrane can wrinkle and fold, and the membrane thickness imposes the value of the maximum curvature locally available to the capsule.

La montée en puissance des groupes industriels et des conglomérats basés en Asie, en Amérique latine, en Europe centrale et orientale, au Moyen-Orient ou bien en Afrique, bouscule les agendas de nombreux fleurons mondiaux et ouvre de nouvelles brèches pour la communauté académique. Elle pose la question de la pérennité de la multinationale d´inspiration anglo-saxonne, longtemps présentée comme la quintessence du capitalisme. Il faut désormais compter avec la Périphérie, ce monde composé de pays émergents et de pays en développement. La Périphérie d´hier et d´aujourd´hui sera le Centre de demain et d´après-demain. Les groupes étatiques et privés chinois rebattent les cartes à l´intérieur et à l´extérieur de celui-ci pour faire la course en tête dans l´économie mondialisée des 50-100 prochaines années. Les études empiriques consacrées aux entreprises originaires des pays émergents (EMNE) fleurissent. A ce jour, aucune nouvelle théorie n´a émergé des débats contradictoires, donnant ainsi crédit au courant évolutionniste. Selon Dunning, Kim et Park (2008), l´internationalisation des EMNE serait la version contemporaine de l´expansion des multinationales des pays développés à la fin des années 1970. Leurs stratégies et leurs modes opératoires ressembleraient à du “vieux vin dans de nouvelles bouteilles”. Le contenu serait quasiment le même. Seul le contenant aurait vraiment changé. Notre recherche vise à décrypter les dynamiques stratégiques, transactionnelles et opérationnelles des groupes chinois dans le monde émergent et en développement. Nous cherchons à comprendre comment le fleurons de l´Empire du Milieu s´emparent de territoires a priori imprenables et préemptent le long terme dans les pays de la Périphérie. Notre étude révèle qu´ils jouissent de leviers et d´atouts spécifiques leur permettant de se battre (war-fighting capabilities) et de conquérir des positions de leaders mondiaux (war-winning capabilities). A rebours du courant évolutionniste, nous mettons en évidence l´originalité des dynamiques chinoises. Les stratégies de conquête des groupes chinois sont travaillées par les questions existentielles (les masses critiques chinoises) et la culture multimillénaire (l´art des combinatoires, la dynamique des flux, l´entresoi) de la Chine. Nous montrons que la préemption institutionnelle habilement orchestrée par l´Etat chinois auprès de la gouvernance défaillante ou mitée des pays hôtes constitue le mode d´entrée privilégié des dragons dans les pays émergents et en développement. Les fleurons chinois investissent massivement dans les vides et déploient des stratégies liquides, que nous appelons “stratégies de l´eau”. Face à elles, les stratégies de la pierre des groupes occidentaux et non occidentaux apparaissent vulnérables. L´eau est supérieure à la pierre. Nos travaux réhabilitent le rôle de la culture dans le champ de la stratégie, et identifient un nouveau paradigme, dénommé IFLC (Institutionalize-Fill-Leverage-Combine), qui pourrait ouvrir la voie à de nouveaux agendas dans le domaine du management stratégique / The rising power of industrial firms and conglomerates from Asia, Latin America, Central and Eastern Europe, the Middle East, and Africa, shakes up the agendas of many global companies and opens the door to further academic research. We argue that it challenges the sustainability of the multinational corporations of Anglo-Saxon inspiration. The Periphery of the global economy composed of emerging and developing countries is likely to shift to the Center in the mid- and long-term. Both Chinese State and private enterprises are reshuffling the cards within and outside the Periphery to gain and, ultimately, preserve a strong leadership in the next 50-100 years. Empirical studies dedicated to emerging market multinationals (EMMs) have failed to create a new theory so far, thus providing material for the advocates of evolutionism. Dunning, Kim and Park (2008) viewed the internationalization of EMMs as the contemporary version of the patterns implemented by developed country multinationals in the late 1970s. According to these authors, the strategies of EMMs, and their execution in the host countries, are “an old wine in new bottles”. The content is similar; only the container is different. Our research aims at decoding the strategic, transactional, and operational dynamics at stake in the maneuver warfare waged by Chinese multinational companies in emerging and developing economies. Our five empirical studies strived to shed a new light on how Chinese multinationals conquer new territories, on how they dismantle invincible positions held by historic players, and on how they preempt the long term in countries of the Periphery. Our survey demonstrates that they leverage an unrivalled collection of specific levers and assets that help them wage the war (war-fighting capabilities) and conquer global leadership positions (war-winning capabilities). Unlike the evolutionist trend, we found out that the Chinese expansion strategies and footprint are unique. They are driven by China’s existential questions (critical masses of resources) and long history. The case studies show that the institutional preemption of the flawed, moth-eaten governance of the host countries, skillfully orchestrated by the Chinese State, is the favorite mode of entry of the Chinese dragons in emerging and developing countries. They also show that the latter invest heavily in voids of all natures (1), and that they deploy liquid strategies named ‘water strategies’ as opposed to ‘stone strategies’ (2). Facing water strategies, the ‘stone strategies’ of Western multinationals appear vulnerable. Our research makes it clear that water wins over the stone. Our findings rehabilitate the role of culture in the field of international strategy, and lead to a new theoretical paradigm: IFLC (Institutionalize – Fill – Leverage – Combine). The IFLC model could pave the way to brand new agendas and practices in strategic management.