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Bonneton, Natalie. „Simulation numérique des jets plans compressibles“. Toulouse, INPT, 1993. http://www.theses.fr/1993INPT031H.
Der volle Inhalt der QuelleLaucoin, Eli. „Développement du parallélisme des méthodes numériques adaptatives pour un code industriel de simulation en mécanique des fluides“. Phd thesis, Grenoble 1, 2008. http://www.theses.fr/2008GRE10174.
Der volle Inhalt der QuelleNumerical resolution of partial differential equations can be made reliable and efficient through the use of adaptive numerical methods. We present here the work we have done for the design, the implementation and the validation of such a method within an industrial software platform with applications in thermal-hydraulics. From the geometric point of view, this method can deal both with mesh refinement and mesh coarsening, while ensuring the quality of the mesh cells. Numerically, we use the mortar elements formalism in order to extend the Finite Volumes-Elements method implemented in the Trio-U platform and to deal with the non-conforming meshes arising from the adaptation procedure. Finally, we present an implementation of this method using concepts from domain decomposition methods for ensuring its efficiency while running in a parallel execution context
Laucoin, Eli. „Développement du parallélisme des méthodes numériques adaptatives pour un code industriel de simulation en mécanique des fluides“. Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00385418.
Der volle Inhalt der QuelleVial, Christophe. „Apport des méthodes de la mécanique des fluides à l'étude des contacteurs gaz/liquide : expérience et simulation numérique“. Vandoeuvre-les-Nancy, INPL, 2000. http://docnum.univ-lorraine.fr/public/INPL_T_2000_VIAL_C.pdf.
Der volle Inhalt der QuelleThis work is devoted to the experimental study, the modelling and the numerical simulation of the hydrodynamics of a bubble column and an external loop airlift reactor. It includes three parts. First, measuring techniques have been developed to study the local and global hydrodynamic parameters of the bubbly flow. In this section, several treatments of the fluctuating wall pressure signal have been developed to identify the prevailing flow regime; three measuring techniques have been adapted to bubbly flows in order to measure the local velocity of the continuous phase: the "Pavlov" tube, an electrochemical method and Laser Doppler Velocimetry. These techniques have completed the methods already available to study the dynamics of the gas phase: local optical probes and an ultrasound Doppler technique. Then, this set of measuring techniques has been used to characterise the hydrodynamics in both reactors. Regime transitions have been deterrnined. The local and global parameters which have been measured are: the gas hold-up; the velocity, the size and the morphology of the bubbles; the liquid velocity and its local fluctuations. The Reynolds shear stress, which could not be measured, has been estimated using a simple model. The evolution of these parameters has been related to the gas flow rate, the gas distribution and the hydrodynamic regime. The whole experimental data are finally compared to the predicted values obtained using a commercial CFD code. Several models of drag, additional forces and turbulence have been used to obtain the best agreement between calculations and experiments. The ability of this commercial code to predict correctly the flow and its current limits have been highlighted
Kong, Jian Xin. „Contribution à l'analyse numérique des méthodes de couplage particules-grille en mécanique des fluides“. Habilitation à diriger des recherches, Grenoble 1, 1993. http://tel.archives-ouvertes.fr/tel-00343556.
Der volle Inhalt der QuelleGillyboeuf, Jean-Philippe. „Diverses méthodes chimère pour la simulation numérique d'écoulements stationnaires“. Toulouse, INPT, 1996. http://www.theses.fr/1996INPT127H.
Der volle Inhalt der QuelleSingh, Jitendra. „Couplage de la méthode intégrale aux frontières en formulation non-primitive et d'une méthode multipolaire pour la simulation d'écoulement incompressibles“. Grenoble INPG, 2009. http://www.theses.fr/2009INPG0148.
Der volle Inhalt der QuelleThe present work addresses the development of the Soundary Element Method (SEM) to model various types of flow in microfluidics devices. Two tasks were carried out; coupling SEM with multipole methods to decrease computational requirements; and a new direction of employing non-primitive variables (N-PV) in SEM formulations. Axisymmetric flow models were considered since, while allowing the realistic modelling of droplets encountered in our applications, they are less computationally demanding than three-dimensional models. The Multipole Method SEM was developed for axisymmetric potential problems and the computation time was reduced by one third. This method was adapted to the simulation of free surface flow problem of drop impact. A new boundary integral formulation for Stokes flows in axisymmetric and three-dimensional problems is developed in the second part. This formulation constitutes an actual advancement in N-PV SEM based on the Helmholtz decomposition and was validated on standard axisymmetric problems
Capatina, Daniela. „Analyse de méthodes mixtes d'éléments finis en mécanique“. Habilitation à diriger des recherches, Université de Pau et des Pays de l'Adour, 2011. http://tel.archives-ouvertes.fr/tel-00647026.
Der volle Inhalt der QuellePaliard, Chloé. „Dimension reduction for fluid simulation and animation“. Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAT023.
Der volle Inhalt der QuelleDespite tremendous improvements in graphics hardware performance aswell as key algorithmic advancements since the beginning of the years 2000, some natural phenomena remain extremely costly to simulate. For instance, several tracks have been proposed to improve the performance of fluid simulations, that are animated by solving partial differential equations (PDE), more specifically the highlynon-linear Navier-Stokes equations. In this thesis, we first explore the use of deep learning to create a reduced space in which a solver can operate with lower costs, while still out putting high-quality solutions. We propose a model that enables the simulation of turbulent flows at a resolution four times higher than that of the given input in each dimension, with improved runtime performance compared to a high-resolution solver. Secondly, we use the contributions on intrinsic operators for simulating fluids on 3D surfaces with reduced costs. We focus on the smoothed-particle hydrodynamics (SPH) model that we adapt to 3D surfaces, by gathering the particles' neighborhoods thanks to shortest-path geodesics, and by displacing such particles in an intrinsic manner on the surface. All of this is straightforward to implement on the GPU, enablingthe simulation of tens of thousands of particles on various triangle meshes at interactive speed
Alauzet, Frédéric. „Adaptation de maillage anisotrope en trois dimensions : applications aux simulations instationnaires en mécanique des fluides“. Montpellier 2, 2003. http://www.theses.fr/2003MON20065.
Der volle Inhalt der QuelleMortazavi, Iraj. „Méthode hybride vortex-éléments finis : étude de la convergence numérique, caractérisation et analyse d'un écoulement complexe“. Lille 1, 1997. http://www.theses.fr/1997LIL10090.
Der volle Inhalt der QuelleRoux, Yann. „Étude de l'amortissement visqueux dans les problèmes de tenue à la mer d'un flotteur immergé“. Le Havre, 1999. http://www.theses.fr/2002LEHA0005.
Der volle Inhalt der QuelleChatelin, Robin. „Méthodes numériques pour l'écoulement de Stokes 3D : fluides à viscosité variable en géométrie complexe mobile : application aux fluides biologiques“. Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00946993.
Der volle Inhalt der QuelleHovnanian, Jessica. „Méthode de frontières immergées pour la mécanique des fluides : application à la simulation de la nage“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00835013.
Der volle Inhalt der QuelleDarbani, Mohsen. „Approche sans maillage basée sur la Méthode des Eléments Naturels (NEM), pour les écoulements bidimensionnels à surface libre“. Compiègne, 2009. http://www.theses.fr/2009COMP1851.
Der volle Inhalt der QuelleSolving equation with free surface often encounters numerical difficulties related to excessive mesh distortion as is the case of dambreak or breaking waves. In this work we explore the meshfree technique based on the Natural Element Method(NEM) to simulate the 2D fluid flow in presence of strong gradients. The equations considered here are those of Saint-Venant shallow water where we consider the full non-linear equations, with a transient flow under the Coriolis effect. The nonlinear terms are computed by using a Lagrangian technique based on the method of the characteristics. This will allow us to avoid setting up a numerical algorithm, like Newton-Raphson’s, which tend to extend the computing time. However, the management of boundary conditions remains a major difficulty in meshless methods. We have therefore defined a thin geometrical domain close to the boundaries and a domain for computing that will be submitted to nodal enrichment, when the particles leave the computational domain
Ghaddab, Driss. „Une Méthode de frontière immergée pour la simulation d'écoulements autour d'objets de forme arbitraire“. Université Louis Pasteur (Strasbourg) (1971-2008), 2001. http://www.theses.fr/2001STR13208.
Der volle Inhalt der QuelleAn immersed boundary method for the simulation of uid ow around arbitrarily shaped objects is presented. It is based on a second order _nite di_erence discretization in a regular cylindrical mesh. Temporal advancement is achieved with a fractional step method using a Runge-Kutta scheme for the non-linear terms and a Crank-Nicholson scheme for the linear terms. Object's geometry is described with a level set method. Near the uid-object interface, linear and non-linear terms are interpolated with second order precision to match wall boundary conditions without a_ecting the stability criteria. The arising Stokes problem is resolved using Uzawa algorithm to ensure second order temporal precision for the pressure. Velocity divergence is calculated with a nite-volume method to ensure mass conservation even near the object wall. The weak formulation of the problem linking the pressure to the divergence makes the Uzawa operator symmetric. The Stokes problem is then numerically solved using a preconditioned conjugate gradient method where the preconditioner is the inverse of the Laplacian which allows an e_cient resolution of the Navier-Stokes equations. The force and the momentum exerted by the uid on the body are computed using a control volume approach. The developed method is compared to a spectral-spectral elements code of sixth order precision previously validated in various works. The case of a sphere in a uniform ow is tested at di_erent ow regimes: stationary axisymmetric regime, stationary non axisymmetric regime and instationary regime. The method is qualitatively as well as quantitatively in good agreement with the results of the higher order spectral code
Wernert, Philippe. „Méthodes de visualisation et de PIV appliquées à l'étude du décrochage dynamique profond et comparaison avec des résultats de simulation numérique“. Aix-Marseille 2, 1997. http://www.theses.fr/1997AIX22110.
Der volle Inhalt der QuelleBeaume, Grégory. „Modélisation et simulation de l'écoulement d'un fluide complexe“. Phd thesis, Paris, ENMP, 2008. http://pastel.paristech.org/5458/01/these_G-Beaume.pdf.
Der volle Inhalt der QuelleThis work is dedicated to numerical simulation of flow of solid-liquid mixtures. The fluid flow obeys a Newtonian behavior and suspended particles are modeled by rigid spheres or sticks. This suspension is appropriate for composites injection molding. Our goal is to better understand the rheological behavior of such a mixture under a shear flow. So we consider the evolution of this mixture in a cubic cell, under a shear flow, with pseudo-periodic boundary conditions. We extend the velocity-pressure equations to solid domain by adding a rigid constraint. Thus we obtain a system of velocity-pressure equations defined on the whole fictitious domain that we solve by a Finite Element method. In this multidomain approach, we have to follow the evolution of the positions of solid particles. The solid domain is represented by a characteristic function. A lagrangian transport is used to update the positions of particles, and the corresponding characteristic function is deduced at any time thanks to a Level-Set method. A collision algorithm is used after this transport to correct positions and prevent particles from interpenetrating. Homogenization calculus have been done in order to estimate equivalent viscosity for suspensions of spheres, and behavior laws and models for evolution of orientation tensors in suspensions of fibers. Boundary effects are reduced thanks to pseudo-periodic boundary conditions. Moreover the interface description is improved by a h-adaptation technique. Our results are in rather good agreement with theoretical models, and a first simulation of a 3D mixture flow is presented
Riffaud, Sébastien. „Modèles réduits : convergence entre calcul et données pour la mécanique des fluides“. Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0334.
Der volle Inhalt der QuelleThe objective of this thesis is to significantly reduce the computational cost associated with numerical simulations governed by partial differential equations. For this purpose, we consider reduced-order models (ROMs), which typically consist of a training stage, in which high-fidelity solutions are collected to define a low-dimensional trial subspace, and a prediction stage, where this data-driven trial subspace is then exploited to achieve fast or real-time simulations. The first contribution of this thesis concerns the modeling of gas flows in both hydrodynamic and rarefied regimes. In this work, we develop a new reduced-order approximation of the Boltzmann-BGK equation, based on Proper Orthogonal Decomposition (POD) in the training stage and on the Galerkin method in the prediction stage. We investigate the simulation of unsteady flows containing shock waves, boundary layers and vortices in 1D and 2D. The results demonstrate the stability, accuracy and significant computational speedup factor delivered by the ROM with respect to the high-fidelity model. The second topic of this thesis deals with the optimal transport problem and its applications to model order reduction. In particular, we propose to use the optimal transport theory in order to analyze and enrich the training database containing the high-fidelity solution snapshots. Reproduction and prediction of unsteady flows, governed by the 1D Boltzmann-BGK equation, show the improvement of the accuracy and reliability of the ROM resulting from these two applications. Finally, the last contribution of this thesis concerns the development of a domain decomposition method based on the Discontinuous Galerkin method. In this approach, the ROM approximates the solution where a significant dimensionality reduction can be achieved while the high-fidelity model is employed elsewhere. The Discontinuous Galerkin method for the ROM offers a simple way to recover the global solution by linking local solutions through numerical fluxes at cell interfaces. The proposed method is evaluated for parametric problems governed by the quasi-1D and 2D Euler equations. The results demonstrate the accuracy of the proposed method and the significant reduction of the computational cost with respect to the high-fidelity model
Becheikh, Nidhal. „Modélisation et simulation numérique de la dégradation photocatalytique d'un polluant modèle dans un microréacteur“. Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0333/document.
Der volle Inhalt der QuelleIndustrial photocatalysis applications requires further research to control and design photocatalytic reactors. The micro structuring of reactors is an innovative solution. It increases the catalytic efficiency by improving the contact of the pollutant with the catalyst. Thesis aim concerned the destruction of a model pollutant, salicylic acid, with deposited catalyst (TiO2) at the bottom of a microchannel. The research is based on experiments and simulations to predict the photocatalytic degradation for a given reactor configuration. In our experimental conditions of low flow, an axial dispersion and a concentration gradient between the catalyst surface and the reaction medium have been demonstrated. We have shown that the gradient of velocity is more pronounced in low cross section microreactors. This gradient allows the formation of recirculation zones near the catalytic surface thus creating favorable conditions for contact between the pollutant and the catalytic surface. Using numerical soft, we have simulated the reaction of photocatalytic degradation to represent our experimental results. On a one hand, the role of diffusion to the catalytic surface has been demonstrated. On the other hand, numerical simulation has allowed to establish a relationship between the Sherwood number as a function of Reynolds number, Schmidt and the hydraulic diameter of the microchannel. This relationship is used to estimate the mass transfer constant to represent correctly the photocatalytic degradation
Himdi, Morjane. „Contribution à la simulation numérique des écoulements de fluides compressibles et peu compressibles par le code de calcul Kiva-II“. Lille 1, 1993. http://www.theses.fr/1993LIL10113.
Der volle Inhalt der QuelleBouchiba, Hassan. „Contributions en traitements basés points pour le rendu et la simulation en mécanique des fluides“. Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM076/document.
Der volle Inhalt der QuelleMost surface 3D scanning techniques produce 3D point clouds. This thesis tackles the problem of using points as only explicit surface representation. It presents two contributions in point-based processing. The first contribution is a new raw and massive point cloud screen-space rendering algorithm. This new method can be applied to a wide variety of data from small objects to complex scenes. A sequence of screen-space pyramidal operators is used to reconstruct in real-time a surface and estimate its normals, which are later used to perform deferred shading. In addition, the use of pyramidal operators allows to achieve framerate one order of magnitude higher than state of the art methods. The second proposed contribution is a new immersed boundary computational fluid dynamics method by extended implicit surface reconstruction. The proposed method is based on a new implicit surface definition from a point cloud by extended moving least squares. This surface is then used to define the boundary conditions of a finite-elements immersed boundary transient Navier-Stokes solver, which is used to compute flows around the object sampled by the point cloud. The solver is interfaced with an anisotropic and adaptive meshing algorithm which refines the computational grid around both the geometry defined by point cloud and the flow at each timestep of the simulation
Glinsky, Nathalie. „Simulation numérique d'écoulements hypersoniques réactifs hors-équilibre chimique“. Nice, 1990. http://www.theses.fr/1990NICE4428.
Der volle Inhalt der QuelleWeber, Carlos. „Développement de méthodes implicites pour les équations de Navier-Stokes moyennées et la simulation des grandes échelles : application à l'aérodynamique externe“. Toulouse, INPT, 1998. http://www.theses.fr/1998INPT045H.
Der volle Inhalt der QuelleDenel, Bertrand. „Simulation numérique et couplage de modèles thermomécaniques puits-milieux poreux“. Pau, 2004. http://www.theses.fr/2004PAUU3021.
Der volle Inhalt der QuelleIn order to interpret recorded temperatures in petroleum wellbores, and thus to better characterize reservoirs, we develop a direct model, coupling the wellbore and the reservoir at both dynamic and thermal levels. To reach this goal, we couple a reservoir model, notably including viscous dissipation and compressibility effect, with a new pseudo 1D model. The original aspect of the latter model is to derive a conform approximation from a 2D model and by this way, to take into account the privileged direction of the flow, as well as the particular geometry of the wellbore, by explicitly writing the dependency of the unknowns in the radial direction. For each model, the fluxes are approximated by conservative Raviart-Thomas elements, ensuring natural transmission conditions at the interface. An analysis of the resulting mixed formulations is carried out and the well-posedness of the semi-discretized problems is established. Then, numerical results including real study cases are presented. Finally, a global coupling approach of the two models is exposed
Sun, Zhengyu. „Simulation numérique par éléments finis de l'hydrodynamique tridimensionnelle à l'intérieur des cuves agitées“. Ecully, Ecole centrale de Lyon, 1989. http://www.theses.fr/1989ECDL0007.
Der volle Inhalt der QuelleFaucher, Eric. „Simulation numérique des écoulements unidimensionnels instationnaires avec autovaporisation“. Phd thesis, Université Paris XII Val de Marne, 2000. http://tel.archives-ouvertes.fr/tel-01026372.
Der volle Inhalt der QuelleOussama, Chikhaoui. „Simulations des grandes échelles et modélisations hybrides RANSE/LES pour le calcul d'écoulements turbulents de grande complexité“. Nantes, 2007. http://www.theses.fr/2007NANT2143.
Der volle Inhalt der QuelleThis PhD thesis deals with the Large Eddy Simulation and the hybrid RANSE/LES modelization. The abilityof ISIS-CFD flow solver, originally designed for solving Reynolds-Averaged Navier-Stokes equations, was extended to these different methods by integrating different turbulence models in order to provide a computing code able to deal with a wide range of academic and industrial complex problems. The models and numerical methods chosen and implemented were justified and validated over several academic test cases and comparisons of LES and hybrid simulations using different flow solvers have been successful. Hybrid methods studied showed a good ability to find expected solutions allowing a large saving in mesh resolution. A criterion based on the assessment of the residual of the momentum budget of the averaged flow is also proposed as an indicator of the numerical errors committed in LES and hybrid simulations. Finally, the simulation of complex turbulent flows using hybrid models have been undertaken. The use of RANS/LES models for the computation of the flow around a skidding simplified car model can reproduce faithfully and cheaply, the experimental observations of a turbulent flow of great complexity
Caleyron, Fabien. „Simulation numérique par la méthode SPH de fuites de fluide consécutives à la déchirure d'un réservoir sous impact“. Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00711040.
Der volle Inhalt der QuelleBasset, Olivier. „Simulation numérique d'écoulements multi-fluides sur grille de calcul“. Phd thesis, École Nationale Supérieure des Mines de Paris, 2006. http://tel.archives-ouvertes.fr/tel-00376484.
Der volle Inhalt der QuelleLouste, Christophe. „Conception d'une méthode de planification de déplacement pour robot mobile selon la méthode des milieux continus appliquée aux fluides visqueux incompressibles“. Montpellier 2, 1999. http://www.theses.fr/1999MON20196.
Der volle Inhalt der QuelleAndrillon, Yann. „Simulation d'écoulements à surface libre par une méthode de capture d'interface en formulation totalement couplée“. Nantes, 2004. http://www.theses.fr/2004NANT2019.
Der volle Inhalt der QuelleLonguemare, Pascal. „Couplage hydromécanique pour des lois de comportement non linéaires : application à des problèmes pétroliers“. Lille 1, 1996. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1996/50376-1996-424.pdf.
Der volle Inhalt der QuelleLleras, Vanessa. „Modélisation, analyse et simulation de problèmes de contact en mécanique des solides et des fluides“. Phd thesis, Université de Franche-Comté, 2009. http://tel.archives-ouvertes.fr/tel-00442074.
Der volle Inhalt der QuelleSantoso, Mas Simon. „Simulation d'écoulements fluides à partir de données réelles“. Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0011.
Der volle Inhalt der QuellePoints clouds are mathematical objects that allows to describe discretely multivariable functions. They are mainly used in the statistical domain but also in geometrical manifolds. It is nowadays a real challenge to immerse the previous manifolds in finite element computation. Indeed, the immersion of those points clouds requires the reconstruction of the surface of the manifold and the generation of a surfacic mesh. As those operations are often based on an iterative process, they are extremely time-consuming as points clouds are usually massive. The method developed in this thesis allows to immerse points clouds in a meshed domain without the surface reconstruction and mesh generations steps. For that purpose, we use the Volume Immersion Method adapted to point clouds. We coupled this method with an adaped mesh generation technique. Then we are able to generate a monolithic anisotropic mesh, adapted around interest zones. We also use the variational multi-scale method to simulate fluid flow. This method is an extension of the classical finite element method and allows to simulate fluid flow. The last part of this thesis introduce some applications cases in the aerodynamic and urbans domains
Morente, Antoine. „Développement d'une méthode de pénalisation pour la simulation d'écoulements liquide-bulles“. Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19922/1/MORENTE_Antoine.pdf.
Der volle Inhalt der QuelleThomine, Olivier. „Développement de méthodes multi-échelles pour la simulation numérique des écoulements réactifs diphasiques“. Phd thesis, Université de Rouen, 2011. http://tel.archives-ouvertes.fr/tel-00683632.
Der volle Inhalt der QuelleNolin, Guillaume. „Une méthode de couplage RANS/LES zonal pour la simulation instationnaire d'écoulements turbulents complexes“. Paris 6, 2007. http://www.theses.fr/2007PA066714.
Der volle Inhalt der QuelleThe relevance of the zonal RANS/LES coupling methods for the unsteady simulation of turbulent flows is presented. The problems to be solved in order to develop a strategy of zonal coupling are outlined. Two of these problems are addressed. The first one is the improvement of the strategies of the zonal coupling to extend the area of influence of the LES zone in the RANS zone as far as possible. The proposed solution is based on an original RANS eddy viscosity reconstruction method, combined with a correction for the RANS turbulence model. The second one deals with the generation of a realistic turbulence at the inflow of the LES domains thanks to an enrichment of the RANS solutions, in order to reduce as much as possible the size of the LES domains. This turbulence is generated through LES inflow conditions based on databases. These techniques are applied to the flow around an airfoil at high Reynolds number and high angle of attack
Serre, Eric. „Instabilités de couche limite dans des écoulements confinés en rotation : Simulation numérique directe par une méthode spectrale de comportements complexes“. Aix-Marseille 2, 2000. http://www.theses.fr/2000AIX2A001.
Der volle Inhalt der QuelleLi, Cuicui. „Analyse a-priori de modèles LES sous-mailles appliqués à la turbulence de paroi avec gradients de pression“. Electronic Thesis or Diss., Ecole centrale de Lille, 2013. http://www.theses.fr/2013ECLI0017.
Der volle Inhalt der QuelleAfter more than 50 years of investigation, Large Eddy Simulation has demonstrated its benefit for unsteady flow simulation and is currently applied in a wide variety of engineering applications. Several classes of subgrid scale models were proposed, including the well known eddy viscosity models, usually preferred because of their simplicities and robustness. The formulation of these models includes a coefficient which needs to be analyzed for each flow configuration and which has been investigated in simple geometries.The aim of the present work is to perform a-priori analysis of subgrid scale models in plane channel flow and in a converging-diverging channel flow at fairly large Reynolds number.The influences of the filter type and filter width are systematically addressed in analyses of all statistics. The SGS energy transfer and energy dissipation are firstly analyzed.Then, the a priori estimate of the coefficients of subgrid scale models, including the standard Smagorinsky, Dynamic Smagorinsky, the WALE and the new updated sigma models, are investigated in detail. It is shown that, the coefficients of the four models are non-homogeneous in the simulation domain and are largely affected by the adverse pressure gradient, especially in the recirculation region. Finally, the correlations between the exact quantities and their counterparts modeled by the subgrid scale models with respect to three criteria are explored. The results show a low predictability of subgrid scale models and a strong variability of the modeled quantities in the region of strong adverse pressure gradient. This may explain the difficulty to obtain accurate LES results in such flow configuration
Moureau, Vincent. „Simulation aux grandes échelles de l'aérodynamique interne des moteurs à piston“. Châtenay-Malabry, Ecole centrale de Paris, 2004. http://www.theses.fr/2004ECAP0952.
Der volle Inhalt der QuelleBrun, Jean-Marc. „Modèles à complexité réduite de transport pour applications environnementales“. Montpellier 2, 2007. http://www.theses.fr/2007MON20248.
Der volle Inhalt der QuelleA platform of low complexity models for the transport of passive scalars for environmental applications is presented. Multi-level analysis has been used with a reduction in dimension of the solution space at each level. Local spray drift distribution is estimated thanks to the turbulent jet theory and determine the source term. Similitude solutions are used in a non symmetric metric for the transport over long distances. Model parameters identification is based on data assimilation. The approach does not require the solution of any PDE and therefore is mesh free. The model also permits to access the solution in one point without computing the solution over the whole domain
Adouobo, Tokou Bernard. „Simulations numériques des méthodes particulaires et particules-maillage sur machines parallèles“. Le Havre, 1998. http://www.theses.fr/1998LEHA0011.
Der volle Inhalt der QuelleBuron, Franck. „Etude d'une nouvelle approche de la méthode Particle-In-Cell pour le calcul d'écoulements instationnaires incompressibles tridimensionnels de fluide parfait ; application au cas de la plaque plane en incidence“. Poitiers, 2000. http://www.theses.fr/2000POIT2255.
Der volle Inhalt der QuelleLouedin, Olivier. „Simulation numérique des processus de mélange 3D dans la zone naissante des jets supersoniques“. Rouen, 1999. http://www.theses.fr/1999ROUES086.
Der volle Inhalt der QuelleCanu, Romain. „Développement d'une méthode compressible avec évaporation pour la simulation d'interface résolue dans le cadre de l'atomisation“. Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR016/document.
Der volle Inhalt der QuelleThis PhD thesis shows the development of a numerical method for solving two-phase flows with vaporisation. A coupling between Level Set and VOF methods is realised for the interface capturing. In order to solve fluid mechanics equations, a pressure based method is employed and, to decouple velocity and pressure, a projection method is performed. This method allows the implicitation of the acoustic terms and the time step constraint reduction. Liquid and gas are considered as compressible allowing local density variations with equations of state. The vaporisation is computed in two different ways ; a first one where the vaporisation rate is constant and a second one, where this rate is calculated by thermodynamics. Along with this topic, a study on curvature distribution in a liquid injection configuration is realised. This study allows to extend the drop size distribution concept in a spray and to improve available informations on ELSA model. Finally, an other study is performed on thedevelopment of a criterion, based on interface curvatures, which estimates the quality of a simulation
Al, Isber Aziz. „Modélisation de l'écoulement instationnaire décollé à la traversée d'un diaphragme par la méthode des vortex aléatoires“. Toulouse, ENSAE, 1991. http://www.theses.fr/1991ESAE0002.
Der volle Inhalt der QuelleEl, Jannoun Ghina. „Adaptation anisotrope précise en espace et temps et méthodes d’éléments finis stabilisées pour la résolution de problèmes de mécanique des fluides instationnaires“. Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0077/document.
Der volle Inhalt der QuelleNowadays, with the increase in computational power, numerical modeling has become an intrinsic tool for predicting physical phenomena and developing engineering designs. The modeling of these phenomena poses scientific complexities the resolution of which requires considerable computational resources and long lasting calculations.In this thesis, we are interested in the resolution of complex long time and large scale heat transfer and fluid flow problems. When the physical phenomena exhibit sharp anisotropic features, a good level of accuracy requires a high mesh resolution, hence hindering the efficiency of the simulation. Therefore a compromise between accuracy and efficiency shall be adopted. The development of space and time adaptive adaptation techniques was motivated by the desire to devise realistic configurations and to limit the shortcomings of the traditional non-adaptive resolutions in terms of lack of solution's accuracy and computational efficiency. Indeed, the resolution of unsteady problems with multi-scale features on a prescribed uniform mesh with a limited number of degrees of freedom often fails to capture the fine scale physical features, have excessive computational cost and might produce incorrect results. These difficulties brought forth investigations towards generating meshes with local refinements where higher resolution was needed. Space and time adaptations can thus be regarded as essential ingredients in this recipe.The approach followed in this work consists in applying stabilized finite element methods and the development of space and time adaptive tools to enhance the accuracy and efficiency of the numerical simulations.The derivation process starts with an edge-based error estimation for locating the regions, in the computational domain, presenting sharp gradients, inner and boundary layers. This is followed by the construction of nodal metric tensors that prescribe, at each node in the spatial mesh, mesh sizes and the directions along which these sizes are to be imposed. In order to improve the efficiency of computations, this construction takes into account a fixed number of nodes and generates an optimal distribution and orientation of the mesh elements. The approach is extended to a space-time adaptation framework, whereby optimal meshes and time-step sizes for slabs of time are constructed in the view of controlling the global interpolation error over the computation domain
Nguyen-Dinh, Maxime. „Qualification des simulations numériques par adaptation anisotropique de maillages“. Phd thesis, Université Nice Sophia Antipolis, 2014. http://tel.archives-ouvertes.fr/tel-00987202.
Der volle Inhalt der QuelleNana, Cyril. „Simulation du bruit d'écoulements anisothermes par méthodes hybrides pour de faibles nombres de Mach“. Phd thesis, Université de Poitiers, 2012. http://tel.archives-ouvertes.fr/tel-00741298.
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