Gradient-based aerodynamic shape optimization, based on Computational Fluid Dynamics analysis of the flow, is a method that can automatically improve designs of aircraft components. The prospect is to reduce a cost function that reflects aerodynamic performances. When the shape is described by a large number of parameters, the calculation of one gradient of the cost function is only feasible by recourse to techniques that are derived from the theory of optimal control. In order to obtain the best computational efficiency, the so called adjoint method is applied here on the complete mapping, from the parameters of design to the values of the cost function. The mapping considered here includes the Euler equations for compressible flow discretized on unstructured meshes by a median-dual finite-volume scheme, the primal-to-dual mesh transformation, the mesh deformation, and the parameterization. The results of the present research concern the detailed derivations of expressions, equations, and algorithms that are necessary to calculate the gradient of the cost function. The discrete adjoint of the Euler equations and the exact dual-to-primal transformation of the gradient have been implemented for 2D and 3D applications in the code Edge, a program of Computational Fluid Dynamics used by Swedish industries. Moreover, techniques are proposed here in the aim to further reduce the computational cost of aerodynamic shape optimization. For instance, an interpolation scheme is derived based on Radial Basis Functions that can execute the deformation of unstructured meshes faster than methods based on an elliptic equation. In order to improve the accuracy of the shape, obtained by numerical optimization, a moving mesh adaptation scheme is realized based on a variable diffusivity equation of Winslow type. This adaptation has been successfully applied on a simple case of shape optimization involving a supersonic flow. An interpolation technique has been derived based on a mollifier in order to improve the convergence of the coupled mesh-flow equations entering the adaptive scheme. The method of adjoint derived here has also been applied successfully when coupling the Euler equations with the boundary-layer and parabolized stability equations, with the aim to delay the laminar-to-turbulent transition of the flow. The delay of transition is an efficient way to reduce the drag due to viscosity at high Reynolds numbers.

Made available in DSpace on 2014-12-17T14:58:17Z (GMT). No. of bitstreams: 1 FelipePMA_DISSERT.pdf: 3715487 bytes, checksum: 630bbbaabad6ec787270701f99c61fb0 (MD5) Previous issue date: 2012-04-18 / A critical problem in mature gas wells is the liquid loading. As the reservoir pressure decreases, gas superficial velocities decreases and the drag exerted on the liquid phase may become insufficient to bring all the liquid to the surface. Liquid starts to drain downward, flooding the well and increasing the backpressure which decreases the gas superficial velocity and so on. A popular method to remedy this problem is the Plunger Lift. This method consists of dropping the "plunger"to the bottom of the tubing well with the main production valve closed. When the plunger reaches the well bottom the production valve is opened and the plunger carry the liquid to the surface. However, models presented in literature for predicting the behavior in plunger lift are simplistic, in many cases static (not considering the transient effects). Therefore work presents the development and validation of a numerical algorithm to solve one-dimensional compressible in gas wells using the Finite Volume Method and PRIME techniques for treating coupling of pressure and velocity fields. The code will be then used to develop a dynamic model for the plunger lift which includes the transient compressible flow within the well / Um problema cr?tico em po?os maduros de g?s ? a carga l?quida. Quando a press?o do reservat?rio diminui, a velocidade superficial diminui e o arrasto exercido na fase l?quida pode se tornar insuficiente para trazer todo o l?quido para a superf?cie. O l?quido come?a a drenar para baixo, afogando o po?o e aumentando a contrapress?o, a qual diminui a velocidade superficial, e assim por diante. Um m?todo popular para remediar esse problema ? o plunger lift. Esse m?todo consiste em derrubar um plunger na fundo coluna de produ??o com a v?lvula principal fechada. Quando o plunger alcan?a o fundo do po?o a v?lvula de produ??o ? aberta e o plunger carrega o l?quido para a superf?cie. Atualmente, os modelos presentes na literatura para prever o comportamento do plunger s?o simplistas, em muitos casos est?ticos (n?o consideram efeitos transientes). Assim, esse trabalho apresenta e valida um algor?timo num?rico para resolver escoamentos em po?os de g?s usando o M?todo dos Volumes Finitos e a t?cnica PRIME para tratar o acoplamento da press?o e velocidade. Esse modelo ser? usado para desenvolver modelos din?micos para plunger lift que incluem efeitos transientes e compress?veis nos escoamentos em po?os

Un fluide porté à une température et pression supérieures à celles du point critique est communément appelé fluide supercritique. Ce fluide possède des propriétés particulièrement intéressantes à cheval entre celles des gaz et celle des liquides. En effet, la masse volumique d’un fluide supercritique est proche de celle d’un liquide tandis que sa viscosité est proche de celle d’un gaz. Une des caractéristiques particulières de ces fluides quand ils s’approchent du point critique est que plusieurs des propriétés thermo-physiques montrent un comportement singulier (compressibilité divergente, diffusivité thermique évanescente etc). Dans ce travail, un modèle mathématique basé sur les équations de Navier-Stokes couplées à celle de l’énergie est proposé afin d’étudier les écoulements de ces fluides très proches de leur point critique. La validation du modèle a été effectuée sur un problème de propagation d’onde acoustique dans l'eau. Nous avons ainsi observé que des solutions précises avec des schémas implicites pour des systèmes non linéaires sont possibles avec des nombres de Courant élevés. L’étude des écoulements dans des fluides supercritiques, lorsqu'ils sont assujettis à une trempe thermique et à une vibration simultanées ont montré que de telles conditions pouvaient conduire à la formation d’instabilités thermo-vibrationnelles, en particulier les instabilités de Rayleigh-vibrationnelles et paramétriques. Les simulations numériques nous ont permis de relever deux phénomènes particulièrement surprenants : (i) la température du fluide à l’intérieur du domaine devient inférieure à la trempe de température imposée à la frontière et (ii) une oscillation des doigts d’instabilité apparaît dans la couche limite thermique dans la direction de la vibration. Dans le cas des fluides sous le point critique (cas diphasique), le modèle compressible développé est couplé à un de champ de phase (“phase field”) dans les conditions isothermes. Des cas tests élémentaires ont été considérés avec succès. Une discussion est proposée afin d’étendre le modèle dans le cas d’une transition continue du régime supercritique au régime sous-critique et vice-versa. / A fluid, in addition to its liquid and gas phase, is known to exist in another phase, wherein the fluid inherits some properties of both the phases. Such a fluid is called a supercritical fluid and the conditions (pressure and temperature) beyond which the fluid exists in this state is called the critical point. One of the peculiar feature of the fluids near the critical point is that the various thermo-physical properties show a singular behavior, such as diverging compressibility, vanishing thermal diffusivity etc. The flow behavior near the critical point leads to intriguing flow features ascribed to the strong thermo-mechanical coupling whose in-depth investigation can be limited by experimental constraints especially during a continuous transition from supercritical to subcritical regime. The current work focuses on analyzing the flow behavior in near-critical fluids with prime focus on supercritical fluids. This is achieved by developing a mathematical and numerical model which is followed by the validation study and error analysis of the numerical scheme wherein unusual behavior of the Courant number is observed. Subsequently, the flow behavior of supercritical fluid is studied when simultaneously subjected to thermal quench and vibration, mainly Rayleigh-vibrational and parametric instabilities, their physical mechanism and various parameters affecting them. In addition, two captivating phenomena, firstly where the temperature of the fluid region drops below the imposed boundary condition and secondly, the see-saw motion of the thermal boundary layer are observed and physical explanations are provided. In order to investigate the flow dynamics in subcritical regime, phase-field modelling approach is explored for isothermal conditions. The model is examined for elementary test cases illustrating the feasibility to extend the model for a continuous transition from supercritical to subcritical regime.

A investigação dos mecanismos de instabilidade pode ter um papel importante no entendimento do processo laminar para turbulento de um escoamento. Análise de instabilidade de uma camada limite de uma linha de estagnação compressível foi realizada no contexto de teoria linear BiGlobal. O estudo dos mecanismos de instabilidade deste escoamento pode proporcionar uma visão útil no desenho aerodinâmico das asas. Um novo procedimento foi desenvolvido e implementado computacionalmente de maneira sequencial e paralela para o estudo de instabilidade BiGlobal. O mesmo baseia-se em formar a matriz esparsa associada ao problema discretizado por dois métodos: pontos de colocação de Chebyshev-Gauss-Lobatto e diferenças finitas, além das combinações destes métodos. Isto permitiu o uso de bibliotecas computacionais eficientes para resolver o sistema linear associado ao problema de autovalor utilizando o algoritmo de Arnoldi. O desempenho do método numérico e código computacional proposto são analisados do ponto de vista do uso de métodos de ordenação dos elementos da matriz, coeficientes de preenchimento, memória e tempo computacional a fim de determinar a solução mais eficiente para um problema físico geral com técnicas de matrizes esparsas. Um estudo paramétrico da instabilidade da camada limite de uma linha de estagnação foi realizado incluindo o estudo dos efeitos de compressibilidade. O excelente desempenho código computacional permitiu obter as curvas neutras e seus respectivos valores críticos para a faixa de número de Mach 0 \'< OU =\' Ma \'< OU =\' 1. Os resultados confirmam a teoria assintótica apresentada por (THEOFILIS; FEDOROV; COLLIS, 2004) e mostram que o incremento do número de Mach reduz o numero de Reynolds crítico e a faixa instável do número de ondas. / Investigation of linear instability mechanisms is essential for understanding the process of transition from laminar to turbulent flow. An algorithm for the numerical solution of the compressible BiGlobal eigenvalue problem is developed. This algorithm exploits the sparsity of the matrices resulting from the spatial discretization of the enigenvalue problem in order to improve the performance in terms of both memory and CPU time over previous dense algebra solutions. Spectral collocation and finite differences spatial discretization methods are implemented, and a performance study is carried out in order to determine the best practice for the efficient solution of a general physical problem with sparse matrix techniques. A combination of spectral collocation and finite differences can further improve the performance. The code developed is then applied in order to revisit and complete the parametric analyses on global instability of the compressible swept Hiemenz flow initiated in (THEOFILIS; FEDOROV; COLLIS, 2004) and obtain neutral curves of this flow as a function of the Mach number in the 0 \'< OU =\' Ma \'< OU =\' 1 range. The present numerical results fully confirm the asymptotic theory results presented in (THEOFILIS; FEDOROV; COLLIS, 2004). This work presents a complete parametric study of the instability properties of modal three dimensional disturbances in the subsonic range for the flow conguration at hand. Up to the subsonic maximum Mach number value studied, it is found that an increase in this parameter reduces the critical Reynolds number and the range of the unstable spanwise wavenumbers.

Cette thèse a pour objectif d'améliorer la compréhension de la dynamique d'une interaction entre une onde de choc droite ou oblique et une couche limite laminaire ou turbulente. En particulier, nous nous sommes intéressés aux mécanismes responsables de l'apparition d'oscillations auto-entretenues basses fréquences. Ce phénomène survient dans de nombreux cas applicatifs comme dans des entrées d'air d'avions supersoniques, autour d'un profil d'aile en régime transsonique et au sein de tuyère en régime de sur-détente. La première partie de ce mémoire traite des différentes études réalisées pour déterminer la phénoménologie de ce type de dynamique. Dans un deuxième temps, nous expliquons la stratégie retenue pour effectuer notre étude qui consiste à développer un outil d'étude des instabilités, adapté à des écoulements turbulents présentant une interaction entre une onde de choc et une couche limite. Le développement d'un outil CFD linéarisé couplé à une méthode de résolution d'un problème aux valeurs propres par une approche dite sans matrice ou de « time-stepping », a permis la réalisation d'une telle étude. Après une étape de validation de notre outil, nous avons étudié des cas d'écoulements présentant une interaction entre une onde de choc et une couche limite. Trois cas en particulier ont été traités. Le premier cas correspond à une interaction entre une onde de choc oblique impactant une couche limite laminaire se développant sur une plaque plane. Ce cas est généralement qualifié dans la littérature de cas de « réflexion de choc ». Nous montrons qu'un tel écoulement est globalement stable et que sa dynamique peut être caractérisée par des mécanismes de réceptivité et par la réponse de l'écoulement vis-à-vis de perturbations extérieures. Les deux autres cas abordés dans ce travail ont été le cas d'un écoulement transsonique autour d'un profil d'aile de type NACA0012 en régime d'entrée en tremblement aérodynamique et un cas de tuyère transsonique plane de type Sajben en régime de sur-détente. Dans le premier cas, l'analyse de stabilité nous permet de mettre en évidence le phénomène de « buffet » sur le profil NACA0012, ce qui montre que le phénomène est lié à une instabilité globale linéaire . Dans le second cas, l'analyse de stabilité ne permet pas d'expliquer le phénomène auto-entretenues basses fréquences, et montre que l'écoulement est linéairement globalement stable. Dans ce cas, la dynamique est convective, transitoire et pilotée par des mécanismes de réceptivité. / The general purpose of this study is to provide a better understanding of the dynamics of an interaction between a shock wave and a laminar or turbulent boundary layer. In particular, we were interested in mechanisms responsible for the emergence of low-frequency self-sustained oscillations. This phenomenon arises in numerous industrial cases as in air inlets of supersonic aircrafts, around a profile of wing in transonic regime and within over-extended nozzle. The first part of this report handles various studies carried out to determine the phenomenology of this kind of dynamics. Secondly, we explain the strategy adopted to make our study which consists in developing a tool of study of the instabilities adapted to turbulent flows including an interaction between a shock wave and a boundary layer. The development of a linearized CFD tool coupled with a method of resolution of a eigenvalue problem by a free-matrix approach ( " time-stepping " approach), allowed the realization of such a study. After a stage of validation of our tool, we studied cases of flows including an interaction between a shock wave and a boundary layer. Three cases in particular were handled. The first case corresponds to an interaction enter an oblique shock wave impacting on a laminar boundary layer developing on a flat plate. This case is generally qualified in the literature of case as " reflected shock wave". We show that such a flow is globally stable and that the dynamics of such a flow behaves as a selective noise amplifier, the dynamic is mainly driven by receptivity mechanisms and by the response of upstream white nose disturbance. Two other cases have been studied on this work, the case of a transonic flow around a profile wing of NACA0012 type around the onset of buffet phenomenon and the case of transonic nozzle of Sajben type on over-extended regime. In the first case, the global stability analysis allows us to highlight the buffet phenomenon of on the profile NACA0012, what shows that the phenomenon is linked to a linear global instability. In the second case, the analysis of stability does not allow to explain the self-sustained low frequencies phenomenon, and shows that the flow is linearly globally stable. In this case, the dynamics is convective, passing and piloted by receptivity mechanisms.

Dans le cadre de l'étude des écoulements ouverts, deux types de dynamiques coexistent. Les écoulements de type oscillateur qui présentent une fréquence propre d'oscillation indépendante des perturbations extérieures (dynamique intrinsèque), ainsi que les écoulements de type amplificateur sélectif de bruit comme les écoulements de jets ou de couches limites décollées, caractérisés par une plus large gamme de fréquences dépendantes essentiellement de bruit extérieur (dynamique extrinsèque). Les études de couches limites décollées en régime incompressible ont montré un lien entre le phénomène auto-entretenu de basse fréquence qui apparaît et l'interaction non normale des modes globaux instables existants pour ce type de configuration. L'objectif de ce travail consiste à étendre cette interprétation lorsque l'écoulement est en régime subsonique. Dans ce but, un travail d'adaptation des conditions aux limites non-réfléchissantes aux problèmes de stabilité globale a été réalisé. Une méthode de zone absorbante de type Perfectly Matched Layer a été implémentée dans un code de simulation numérique utilisant des méthodes de collocation spectrale. Une méthode de décomposition de domaine adaptée aux calculs des solutions stationnaires ainsi qu'aux problèmes de stabilité globale a également été utilisée pour permettre la validation des conditions aux limites implémentées sur un cas d'écoulement rayonnant de cavité ouverte. Enfin, les études de stabilité d'un écoulement de couche limite décollée derrière une géométrie de type bosse ont été réalisées. L'étude des instabilités bidimensionnelles, responsables du phénomène basse fréquence (flapping), et réalisées en régime subsonique montre que le mécanisme observé en régime incompressible est aussi observé en régime subsonique. La stabilité de cet écoulement vis-à-vis de perturbations tri-dimensionnelles, et plus particulièrement les instabilités centrifuges ont aussi été étudiées en fonction du nombre de Mach. / In open flows context, there are generally two types of dynamic : oscillators, such as cylinder flow, exhibit a well defined frequency insensitive to external perturbations (intrinsic dynamics) and noise amplifiers, such as boundary layers, jets or in some cases the separated flows, which are characterized by wider spectrum bands that depend essentially on the external noise (dynamic extrinsic). Previous studies have shown that separated flows are subject to self-induced oscillations of low frequency in incompressible regime. These studies have revealed links between the interaction of non-normal modes and low oscillations in an incompressible boundary-layer separation and it will be to establish the validity of this interpretation in a compressible regime. In this regard, non-reflecting boundary conditions have been developed to solve the eigenvalue problem formed by linearised Navier-Stokes equations. An absorbing region known as Perfectly Matched Layer has been implemented in order to damp acoustic perturbations which are generated when the compressibility of the flow is considered. A multi-domain approach using spectral collocation discretisation has also been developed in order to study the influence of this absorbing region on the stability analysis of an open cavity flow which is known to generate acoustic perturbations. Finally, we focused on separated boundary layer induced by a bump geometry in order to understand what are the effects of compressibility on the bidimensional low frequency phenomenon and also on transverse instabilities which are known to be unstable for a lots of separated flows.

Experiments are done using a smooth solid rigid homogeneous acrylic sphere rolling on an inclined plane which is submerged in water. The motivation for these experiments comes from a need to understand a class of solid-fluid interaction problems that include sediment transport, movement of gravel on ocean floor and river bed due to water currents. Experiments are performed in a glass water tank 15 cm wide by 14 cm deep by 61 cm long which can be tilted to desired angle. The sphere is released from rest on the inclined false bottom of the tank in quiescent water. Our experimental study has twofold aim: (1)to study the boundary layer separation, the three-dimensional eddying motion in the wake and the near-wake structure and(2) to establish hydrodynamic force coefficients by analyzing kinematical data of the sphere motion from start to till it attains terminal velocity. Experiments are carried out at moderate Reynolds number Rearound1500. Previous studies on the first problem exist in the literature for Reup to 350. Previous studies on the second problem do not clearly define the added-mass coefficient and the influence of the water tank side-walls on the drag coefficient. In the first study, the characterization of the wake is done using flow visualization methods (fluoresce in dye visualization and particle streak visualization) and Particle Image Velocimetry (PIV). Laser light sheet obtained from an argon ion continuous laser beam is taken in different orientations to illuminate the fluoresce in dye or 14 m silver-coated hollow glass spheres. These experiments show that the wake behind the rolling sphere up to 1.6 diameters (or 1.6D) downstream is confined within height 1.2Dand width1.2D. At about 1.8Ddownstream, the wake sways alternately on either side of the equatorial plane, moving in lateral-vertical direction and moving out of the confining region; this gives zigzag appearance to the wake. Also in these experiments, we observe that the flow separations from the surface of the rolling sphere show three separation zones. The eddies shed from the primary separation surface on the upper hemisphere are symmetrical about the equatorial plane with Strouhal number St=1.0. The primary separation is affected by the symmetrical secondary separations on the rear surface in the piggyback region — it is the region near the upper rear surface of the sphere behind the transverse equatorial plane and below the primary separation surface. The lower eddies below the primary separation zone are shed alternately on either side of the equatorial plane with shedding frequency St=0.5. Our experiments show that there is a viscous blockage of width 0.4Dat the crevice near the point of contact. On either side of the viscous blockage at the crevice, we see weak symmetric eddies. Based on our experimental observations, we proceed to build a simple physical model of the separated flow on the surface of the rolling sphere. In the second study, the motion of the sphere is photographed and paired data of the displacement and time is obtained for the sphere motion from the start of motion till terminal velocity is reached at about 4.5 sphere diameters from the point of release of the sphere. Equation of motion of the sphere is solved numerically treating added-mass coefficient Ca and drag coefficient Cd as parameters. Experimental data is fitted on these solutions and the best fit gives the values of the force coefficients. Theoretical value of Ca equal to 0.621 is confirmed experimentally. Value of Cd is found to be 1.23 at Re=990 and it is 1.06 at Re= 1900. Side-wall effects become important for ratio of diameter of sphere to width of tank greaterthan0.20.

The motion of shock waves is important in many fields of engineering and increasingly so with medical applications and applications to inertial confinement fusion technologies. The flow structures that moving shock waves create when they encounter a change in area is complex and can be difficult to understand. Previousresearchers have carried out experimental studies and many numerical studies looking at this problem in more detail. There has been a discrepancy between numerical and experimental work which had remained unanswered. One of the aims of this project is to try and resolve the discrepancy between numerical and experimental work and try to investigate what experimental techniques are suitable for work of this type and the exact way in which they should be applied. Most previous work has focused on sharp changes in geometry which induce immediate flow separation. In this project rounded corners will also be investigated and the complex flow features will be analyzed.Two geometries, namely a sharp 172 degree knife-edge and a 2.8 mm radius rounded corner will be investigated at three experimental pressure ratios of 4, 8 and 12 using air as the driver gas. This yields experimental shock Mach numbers of 1.28, 1.46 and 1.55. High-speed schlieren and shadowgraph photography with varying levels of sensitivity were used to qualitatively investigate the wave structures. Particle image velocimetry (PIV), pressure-sensitive paint (PSP) and traditional pressure transducers were used to quantify the flow field. Numerical simulations were performed using the commercial package Fluent to investigate the effect of numerical schemes on the flow field produced and for comparison with the experimental results. The sharp geometry was simulated successfully using an inviscid simulation while the rounded geometry required the addition of laminar viscosity. Reynolds number effects will be only sparsely referred to in this project as the flows under investigation show largely inviscid characteristics. As the flow is developing in time rather than in space, quotation of a distance-based Reynolds number is not entirely appropriate; however, Reynolds number based on the same spatial location but varying in time will be mentioned. The density-based diagnostics in this project were designed to have a depth of field appropriate to the test under consideration. This approach has been used relatively few times despite its easy setup and significant impact on the results. This project contains the first quantative use of PIV and PSP to shock wave diffraction. Previous studies have almost exclusively used density-based diagnostics which, although give the best impression of the flow field, do not allow for complete analysis and explanation of all of the flow features present. PIV measurements showed a maximum uncertainty of 5% while the PSP measurements showed an uncertainty of approximately 10%.The shock wave diffraction process, vortex formation, shear layer structure, secondary and even tertiary expansions and the shock vortex interaction were investigate. The experimental results have shown that using one experimental technique in isolation can give misleading results. Only by using a combination of experimental techniques can we achieve a complete understanding of the flow field and draw conclusions on the validity of the numerical results. Expanding the range of the experimental techniques currently in use is vital for experimental aerodynamic testing to remain relevant in an industry increasingly dominated by numerical research. To this end, significant research work has been carried out on extending the range of the PSP technique to allow for the capture of shock wave diffraction, one of the fastest transient fluid processes, and for applications to low-speed flow (< 20 ms−1).

No description available.

Dans certaines simulations numériques exigeantes de mécanique des fluides, ilest nécessaire de simuler des écoulements multiphasiques impliquant de nombreuses contraintes simultanées : nombre de fluides important, évolutions compressibles à la fois isentropes et fortement choquées, équations d’états variables et contrastées, déformations importantes et transport surdes longues distances. Afin de remplir ces objectifs de manière robuste, il est nécessaire que la cohérence thermodynamique du schéma numérique soit vérifiée.Dans le premier chapitre, un schéma de type Lagrange plus projection est proposé pour la simulation d’écoulements diphasiques avec un modèle squelette à six équations et sans termes de dissipation. L’importance de la propriété de préservation des écoulements isentropiques est mise en évidence à l’aide d’une comparaison avec des résultats issus de la littérature pour le test deRansom. Ce chapitre souligne aussi certaines limitations de l’approche Lagrange plus projection pour simuler des modèles multiphasiques.Afin de pallier à ces limitations, une nouvelle procédure de dérivation est proposée afin de construire un schéma mimétique pour la simulation d’écoulements instationnaires compressibles dans un formalisme ALE direct (Arbitrary Lagrangian–Eulerian). La possibilité de choisir a prioriles degrés de liberté permet de s’inscrire dans une continuité avec les schémas historiques décalés, tout en imposant les conservations au niveau discret. L’équation de quantité de mouvement discrèteest obtenue par application d’un principe variationnel, assurant par construction la cohérence thermodynamique des efforts de pression. Cette approche est appliquée au cas d’écoulements monofluides comme preuve de concept au Chapitre 3, puis elle est étendue au cas d’écoulements à Nphasescompressibles au Chapitre 4. Des tests mono et multiphasiques montrent un comportement satisfaisant en terme de conservativité, versatilité aux mouvements de grilles et robustesse. / In some highly demanding fluid dynamics simulations, it appears necessary tosimulate multiphase flows involving numerous constraints at the same time : large numbers of fluids, both isentropic and strongly shocked compressible evolution, highly variable and contrasted equations of state, large deformations, and transport over large distances. Fulfilling such a challengein a robust and tractable way demands that thermodynamic consistency of the numerical scheme be carefully ensured.In the first chapter, a Lagrange plus remap scheme is proposed for the simulation of two-phase flows with a dissipation-free six-equation bakcbone model. The importance of the property of isentropic flow preservation is highlighted with a comparison with Ransom test results fromthe literature. This chapter also also point out certain limitations of the Lagrange plus remap approach for multiphase simulations.In order to overcome these limitations, a novel derivation procedure is proposed to construct a mimetic scheme for the simulation of unsteady and compressible flows in a direct ALE (ArbitraryLagrangian-Eulerian) formalism. The possibility to choose a priori the degrees of freedom allows to obtain a continuity with historical staggered scheme, while imposing conservativity at discretelevel. The discrete momentum evolution equation is obtained by application of a variational principle, thus natively ensuring the thermodynamic consistency of pressure efforts. This approach is applied to single-fluid flows as a proof of concept in Chapter 3, then it is extended to N-phasecompressible flows in Chapter 4. Single- and multi-phase tests show satisfactory behavior in terms on conservation, versatility to grid motions, and robustness.