Дисертації з теми "Adaptation de maillages anisotropes"
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Bois, Richard. "Adaptation de maillages anisotropes par un estimateur d'erreur hiérarchique." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29273/29273.pdf.
In this thesis, we present a new hierarchical error estimator that can be used in a mesh adaptation algorithm to obtain a more accurate approximation to the solution of a partial differential equation. This error estimator has many advantages that other existing error estimators do not have or lack of. For instance, it is, by construction, independant of the differential operator used to model a certain physical phenomena. It is also naturally generalisable to the case of approximations of arbitrary order, and this, without any specific treatment to the underlying theory. Finally, it is efficient, optimal in a sense that will be defined and permits the elements to stretch in a priviledged direction (anisotropy) in order to obtain high accuracy against regularly refined meshes. Many examples are given in the one, two and three dimensional cases. Analytical examples (the solution is known) is given to measure the effiency and precision of the new error estimator. Other examples of mesh adaptation for equations modeling different physical phenomena like the flow of a fluid around a cylinder, unsteady diffusion and contact between deformable elastic bodies are presented. These examples show that the new error estimator can be used for a wide variety of problems.
Rouxel-Labbé, Mael. "Génération de maillages anisotropes." Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4150/document.
In this thesis, we study the generation of anisotropic meshes using the concepts of Delaunay triangulations and Voronoi diagrams. We first consider the framework of locally uniform anisotropic meshes introduced by Boissonnat, Wormser and Yvinec. Despite known theoretical guarantees, the practicality of this approach has only been hardly studied. An exhaustive empirical study is presented and reveals the strengths but also the overall impracticality of the method. In a second part, we investigate the anisotropic Voronoi diagram introduced by Labelle and Shewchuk and give conditions on a set of seeds such that the corresponding diagram has a dual that is an embedded triangulation in any dimension; an algorithm to generate such sets is devised. Using the same diagram, we propose an algorithm to generate efficiently anisotropic triangulations of low-dimensional manifolds embedded in high-dimensional spaces. Our algorithm is provable, but produces disappointing results. Finally, we study Riemannian Voronoi diagrams and introduce discrete Riemannian Voronoi diagrams, which employ recent developments in the numerical computation of geodesic distances and whose computation is accelerated through the use of an underlying anisotropic graph structure. We give conditions that guarantee that our discrete structure is combinatorially equivalent to the Riemannian Voronoi diagram and that its dual is an embedded triangulation, using both straight and curved simplices. We obtain significantly better results than with our other methods, but the overall utility of
Zerguine, Walid. "Adaptation de maillages anisotropes et écoulements multifluides : Applications en injection assistée eau." Paris, ENMP, 2010. http://www.theses.fr/2010ENMP0082.
The Water Assisted Injection Molding (WAIM) is a recent manufacturing process that produces thermoplastic hollow parts. Numerical simulation is an important step in the development of this innovative technology. The framework of the thesis is the development of a numerical simulation module for the WAIM process. The industrial and technological benefits of this numerical tool will provide crucial information on the sensitivity of the properties of injection molded parts to injection conditions. The hydrodynamics of the multiphase polymer-water-air system is described by the resolution of the Navier-Stokes equations within the framework of an eulerian monolithic formulation. The method consists in solving the system of equations on a single mesh. A distance function allows to describe the interfaces water-polymer and polymer-air to supply the physical properties of every sub-domain. A strategy of anisotropic dynamic mesh adaptation allows to decrease the strong heterogeneities of the phases in presence. Two ways are investigated. The first one considers meshes constructed from a priori metrics based on the gradient of the Levelset function and the second approach considers the construction of a metric based on a posteriori error estimator minimizing the error of approximation under constraint to keep a constant number of elements. A confrontation in experimental trials confirms the relevance of our tool to predict the evolution of the water vein in a typical WAIM part
Vallet, Marie-Gabrielle. "Génération de maillages éléments finis anisotropes et adaptatifs." Paris 6, 1992. http://www.theses.fr/1992PA066625.
Tye, Gingras Christian. "Adaptation de maillages en parallèle." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30478/30478.pdf.
Kuate, Raphaël. "Adaptation de maillage anisotrope : étude, construction d'estimateurs d'erreur et raffinement hexaédrique." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00363511.
Boiteau, Éloïse. "Adaptation de maillage anisotrope : définition d'une métrique pour discrétisations de degré élevé." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29325/29325.pdf.
Gruau, Cyril. "Génération de métriques pour adaptation anisotrope de maillages : applications à la mise en forme des matériaux." Phd thesis, École Nationale Supérieure des Mines de Paris, 2004. http://pastel.archives-ouvertes.fr/pastel-00000989.
Barral, Nicolas. "Time-accurate anisotropic mesh adaptation for three-dimensional moving mesh problems." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066476/document.
Time dependent simulations are still a challenge for industry, notably due to problems raised by moving boundaries, both in terms of CPU cost and accuracy. This thesis presents contributions to several aspects of simulations with moving meshes. A moving-mesh algorithm based on a large deformation time step and connectivity changes (swaps) is studied. An elasticity method and an Inverse Distance Weighted interpolation method are compared on many 3D examples, demonstrating the efficiency of the algorithm in handling large geometry displacement without remeshing. This algorithm is coupled with an Arbitrary-Lagrangian-Eulerian (ALE) solver, whose schemes and implementation in 3D are described in details. A linear interpolation scheme is used to handle swaps. Validation test cases showed that the use of swaps does not impact notably the accuracy of the solution, while several other complex 3D examples demonstrate the capabilities of the approach both with imposed motion and Fluid-Structure Interaction problems. Metric-based mesh adaptation has proved its efficiency in improving the accuracy of steady simulation at a reasonable cost. We consider the extension of these methods to unsteady problems, updating the previous fixed-point algorithm thanks to a new space-time error analysis based on the continuous mesh model. An efficient p-thread parallelization enables running 3D unsteady adaptative simulations with a new level of accuracy. This algorithm is extended to moving mesh problems, notably by correcting the optimal unsteady metric. Finally several 3D examples of adaptative moving mesh simulations are exhibited, that prove our concept by improving notably the accuracy of the solution for a reasonable time cost
Couet, Alexandre. "Adaptation de maillage anisotrope : méthode pleinement optimale basée sur un estimateur d'erreur hiérarchique en dimension 3." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28625/28625.pdf.
Mirebeau, Jean-Marie. "Approximation adaptative et anisotrope par éléments finis : Théorie et algorithmes." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00544243.
Olivier, Géraldine. "Adaptation de maillage anisotrope par prescription de champ de métriques appliquée aux simulations instationnaires en géométrie mobile." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00739406.
Claisse, Alexandra. "Modèle de reconstruction d'une surface échantillonnée par une méthode de ligne de niveau, et applications." Paris 6, 2009. https://tel.archives-ouvertes.fr/tel-00443640.
Claisse, Alexandra. "Modèle de reconstruction d'une surface échantillonnée par un méthode de ligne de niveau, et applications." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00443640.
Coorevits, Patrice. "Maillage adaptatif anisotrope : application aux problèmes de dynamique." Cachan, Ecole normale supérieure, 1993. http://www.theses.fr/1993DENS0002.
Bazile, Alban. "Formulation éléments finis variationnelle adaptative et calcul massivement parallèle pour l’aérothermique industrielle." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM008/document.
By 2030, considering the progress of HPC, aerospace manufacturers like Safran Aircraft Engines (SAE), hope to be able to simulate a whole aircraft engine, at full scale, using Computational Fluid Dynamic (CFD). The goal of this PhD thesis is to bring a scientific contribution to this research framework. Indeed, the present work is devoted to the development of a variational adaptive finite element method allowing to improve the aerothermal simulations related to the turbine blade cooling. More precisely, our goal is to develop a new multiscale mesh adaptation technique, well suited to the resolution of highly convective heat transfers in turbulent flows. To do so, we propose a hierarchical control of errors based on recently developed subscales VMS error estimators. The first contribution of this work is then to propose a new isotropic mesh adaptation technique based on the previous error estimates. The second contribution is to combine both (i) the coarse scales interpolation error indicator and (ii) the subscales error estimator for anisotropic mesh adaptation. The results on analytic 2D and 3D benchmarks show that the proposed multiscale mesh adaptation technique allows obtaining highly precise solutions with much less elements in comparison with other mesh adaptation techniques. Finally, we propose in this thesis a description of the parallel software capabilities of Cimlib-CFD. Then, we present the two hardware systems used during this PhD thesis. The first one is the lab's cluster allowing the development of numerical methods. The second one however, is the GENCI Occigen II supercomputer which allows producing numerical results using massively parallel computations. In particular, we present a more realistic industrial concerning the cooling of a complete turbine vane composed by 39 holes
Zhao, Jiaxin. "Génération de maillage à partir d'images 3D en utilisant l'adaptation de maillage anisotrope et une équation de réinitialisation." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM004/document.
Imaging techniques have well improved in the last decades. They may accurately provide numerical descriptions from 2D or 3D images, opening perspectives towards inner information, not seen otherwise, with applications in different fields, like medicine studies, material science or urban environments. In this work, a technique to build a numerical description under the mesh format has been implemented and used in numerical simulations when coupled to finite element solvers. Firstly, mathematical morphology techniques have been introduced to handle image information, providing the specific features of interest for the simulation. The immersed image method was then proposed to interpolate the image information on a mesh. Then, an iterative anisotropic mesh adaptation operator was developed to construct the optimal mesh, based on the estimated error concerning the image interpolation. The mesh is thus directly constructed from the image information. We have also proposed a new methodology to build a regularized phase function, corresponding to the objects we wish to distinguish from the image, using a redistancing method. Two main advantages of having such function are: the gradient of the regularized function performs better for mesh adaptation; the regularized function may be directly used for the finite element solver. Stabilized finite element flow and advection solvers were coupled to the constructed anisotropic mesh and the redistancing function, allowing its application to multiphase flow numerical simulations. All these developments have been extended in a massively parallel context. An important objective of this work is the simplification of the image based computations, through a modified way to segment the image and by coupling all to an automatic way to construct the mesh used in the finite element simulations
Dobrzynski, Cécile. "Adaptation de Maillage anisotrope 3D et application à l'aéro-thermique des bâtiments." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00120327.
Nous avons utilisé une méthode d'adaptation de maillage anisotrope basée sur les longueurs d'arêtes avec respect d'une métrique discrète. Une méthode de remaillage local, avec une version anisotrope de l'insertion d'un point par une méthode de Delaunay, a été implémentée pour adapter les maillages.
Dobrzynski, Cécile. "Adaptation de maillage anisotrope 3D et application à l' aéro-thermique des bâtiments." Paris 6, 2005. https://tel.archives-ouvertes.fr/tel-00120327.
Gauci, Éléonore. "Adaptation de maillage orientée fonctionnelle et basée sur une métrique pour des simulations aérodynamiques en géométrie variable." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4227/document.
When dealing with CFD problems, mesh adaptation is interesting for its ability to approach the asymptotic convergence and to obtain an accurate prediction for complex flows at a lower cost. Anisotropic mesh adaptation method reduces the number of degrees of freedom required to reach a given solution accuracy, thus impact favorably the CPU time. Moreover, it reduces the numerical scheme dissipation by automatically taking into account the anisotropy of the physical phenomena inside the mesh. Two main approaches exist in the literature. Feature-based mesh adaptation which is mainly deduced from an interpolation error estimate using the Hessian of the chosen sensor controls the interpolation error of the sensor over the whole computational domain. Such approach is easy to set-up and has a wide range of application, but it does not take into account the considered PDE used to solve the problem. On the other hand, goal-oriented mesh adaptation, which focuses on a scalar output function, takes into consideration both the solution and the PDE in the error estimation thanks to the adjoint state. But, the design of such error estimate is much more complicated. This thesis presents the results obtained with different CFD methods : the Arbitrary Lagrangian Eulerian (ALE) flow solvers with explicit and implicit schemes are presented and coupled to the moving mesh process, the feature-based unsteady mesh adaptation for moving geometries takes into account the changes of connectivites during the whole simulation, the adjoint state is extended to moving geometries problems and goal-oriented unsteady mesh adaptation for moving meshes is derived from an a priori error estimate. Several numerical examples are considered in the aeronautics sector and the field of civil security
Farestam, Stefan. "Génération de maillages non-structurés anisotropes sur des variétés bidimensionnelles." Toulouse, INPT, 1993. http://www.theses.fr/1993INPT076H.
Guégan, Damien. "Modélisation numérique d'écoulements bifluides 3 D instationnaires avec adaptation de maillage." Nice, 2007. http://www.theses.fr/2007NICE4097.
The purpose of this thesis is to develop a numerical method dedicated to the prediction of multifluid flows. We work with unsteady Navier-Stokes equations. The fluids are considered incompressible and immiscible. We use a projection method to discretize these equations, whereas interface tracking is enforced by the Level Set method. We propose a sharp interface method, the Ghost Fluid Method, to take into account a thin interface discontinuity, on unstructured meshes. We present a comparison with dispersed interface method. An important part of our work is devoted to the development of a coupling between Navier-Stokes solver and mesh adaptation technique. After the description of these technique, we propose solutions to efficiently adapt meshes to bifluid flows. Our approach is validated on academic tests cases and tested on several simulations 2D and 3D more complicated. Comparisons with experiments are presented
Mesri, Youssef. "Gestion et contrôle des maillages non structurés anisotropes : applications en aérodynamique." Nice, 2007. http://www.theses.fr/2007NICE4096.
Our contribution concerns the following three complementary domains: optimal shape design and meshes, mesh coarsening for multigrids methods and mesh partitioning. The motivation of the first part, is the reduction of the sonic boom emitted by a transport aircraft. Initially, we integrated a mesh adaptation strategy based on local criteria in a optimization loop. Then we tested a new model of non-local adaptation criteria based on the combination of: "continuous metrics" and "Adjoint". This new combination allows in particular to minimize the error of approximation made on the cost functional. The second part is devoted to the development of a method of generation of sequences of coarsened 3D unstructured meshes starting from a fine and very anisotropic initial mesh. The resulting meshes are used as grids of a multigrid solver for the Navier-Stokes equations. The coarsened mesh is generated starting from the initial mesh and a target metric obtained by coarsening the natural metric calculated on the fine grid. The third part is devoted to the problem of mesh partitioning on heterogeneous architectures. The problem of mesh partitioning in homogeneous architectures is largely studied. However, the existing schemes fail when the target architecture introduces heterogeneity in resources. In this part, we present a new hierarchical mesh partitioning algorithm, taking into account the heterogeneity of CPU and the network
Alauzet, Frédéric Mohammadi Bijan. "Adaptation de maillage anisotrope en trois dimensions applications aux simulations instationnaires en mécanique des fluides /." [S.l.] : [s.n.], 2003. http://www.inria.fr/rrrt/tu-0791.html.
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.
Gaillet, Christophe. "Optimisation et adaptation de maillages tridimensionnels." Paris 6, 1994. http://www.theses.fr/1994PA066578.
Pelletier, Gino. "Adaptation de maillages et flexion des plaques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0011/MQ41985.pdf.
Frazza, Loïc. "3D anisotropic mesh adaptation for Reynolds Averaged Navier-Stokes simulations." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS423.
The fast and reliable simulation of turbulent flow using Reynolds Averaged Navier Stokes (RANS) models is a major financial issue for many industries. With the increasing complexity of geometries and simulated flows, as well as requirements in terms of fidelity, the generation of appropriate meshes has become a key link in the chain of computation. We show in this thesis the ability of modern numerical schemes to simulate turbulent flows on fully unstructured meshes generated automatically using mesh adaptation methods. We present the implementation of different versions of the Spalart-Allmaras model as well as the numerical choices guaranteeing a sufficient robustness of the solver in order to not require a structured boundary layer. We then introduce the error analysis necessary to propose different error estimators for mesh optimization. This methodology is tested on various external aerodynamic and turbomachinery test cases and compared to traditional mesh generation methods. We show the ability of mesh adaptation methods to automatically generate optimal mesh sizes for RANS simulations on realistic and complex geometries
Bui, Thi Thu Cuc. "Simulation des écoulements bifluides, une stratégie de couplage basée sur l'adaptation de maillage anisotrope." Paris 6, 2009. http://www.theses.fr/2009PA066372.
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.
Heschung, Frédéric Gardan Yvon. "Vers une construction et une adaptation automatiques des maillages." Reims : S.C.D. de l'Université, 2005. http://scdurca.univ-reims.fr/exl-doc/GED00000155.pdf.
Heschung, Frédéric. "Vers une construction et une adaptation automatiques des maillages." Reims, 2005. http://theses.univ-reims.fr/exl-doc/GED00000155.pdf.
During the design cycle of a product, it is meshed to be used in various applications : visualization, rapid prototyping and finite element analysis. Current meshing tools require human interventions in order 1) to repair the CAD models or the meshes that have cracks or overlapping elements, and 2) to input the preparation data of the meshes. The objective of this work is to offer to a non expert user the possibility to obtain good quality meshes, as automatically as possible, respecting the applications needs. Our contribution is based on four points. 1) A software architecture specialized in mesh production. 2) A meshing algorithms library that, due to a limited set of geometric services, does not rebuild the geometric model and saves from the errors generated by the reconstruction. Since the geometric model is not rebuild, we propose to control the global meshing process from the CAD software, by the so called 3) assembly module that, being part of the CAD software, knows the entities to be meshed. Thus, this module can make the most of the CAD information pieces to specify mesh properties such as nodes density. Finally, the extensibility of the meshing algorithms library is achieved through 4) generic algorithms dedicated to meshing: when a new meshing technique is inserted, only its specific aspects are coded ; all the other ones, which includes its skeleton and subroutines, can be copied from already stored techniques
Ong, Thanh Hai. "Schémas volumes finis pour des opérateurs de diffusion anisotropes hétérogènes sur des maillages non-conformes." Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00794875.
Stephansen, Annette. "Méthodes de Galerkine discontinues et analyse d'erreur a posteriori pour les problèmes de diffusion hétérogène." Marne-la-vallée, ENPC, 2007. http://www.theses.fr/2007ENPC0722.
Mbinky, Estelle. "Adaptation de maillages pour des schémas numériques d'ordre très élevé." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00923773.
Mbinky, Estelle Carine. "Adaptation de maillages pour des schémas numériques d'ordre très élevé." Paris 6, 2013. http://www.theses.fr/2013PA066696.
Mesh adaptation is an iterative process which consists in changing locally the size and orientation of the mesh according the behavior of the studied physical solution. It generates the best mesh for a given problem and a fix number of degrees of freedom. Mesh adaptation methods have proven to be extremely effective in reducing significantly the mesh size for a given precision and reaching quickly an second-order asymptotic convergence for problems containing singularities when they are coupled to high order numerical methods. In metric-based mesh adaptation, two approaches have been proposed: Multi-scale methods based on a control of the interpolation error in Lp-norm and Goal oriented methods that control the approximation error of a functional through the use of the adjoint state. However, with the emergence of very high order numerical methods such as the discontinuous Galerkin method, it becomes necessary to take into account the order of the numerical scheme in mesh adaptation process. Mesh adaptation is even more crucial for such schemes as they converge to first-order in flow singularities. Therefore, the mesh refinement at the singularities of the solution must be as important as the order of the method is high. This thesis deals with the extension of the theoretical and numerical results getting in the case of mesh adaptation for piecewise linear solutions to high order piecewise polynomial solutions. These solutions are represented using kth-order Lagrangian finite elements (k ≥ 2). This thesis will focus on modeling the local interpolation error of order k ≥ 3 on a continuous mesh. However, for metric-based mesh adaptation methods, the error model must be a quadratic form, which shows an intrinsic metric space. Therefore, to be able to produce such an area, it is necessary to decompose the homogeneous polynomial and to approximate it by a quadratic form taken at power k. This modeling allows us to define a metric field necessary to communicate with the mesh generator. The decomposition method will be an extension of the diagonalization method to high order homogeneous polynomials. Indeed, in 2D and 3D, symmetric tensor decomposition methods such as Sylvester decomposition and its extension to high dimensions will allow us to decompose locally the error function, then, to deduce the quadratic error model. Then, this local error model is used to control the overall error in Lp-norm and the optimal mesh is obtained by minimizing this error. In this thesis, we seek to demonstrate the kth-order convergence of high order mesh adaptation method for analytic functions and numerical simulations using kth-order solvers (k ≥ 3)
Loseille, Adrien. "Adaptation de maillage anisotrope 3D multi-échelles et ciblée à une fonctionnelle pour la mécanique des fluides.Application à la prédiction haute-fidélité du bang sonique." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00361961.
Loseille, Adrien. "Adaptation de maillage anisotrope 3D multi-échelles et ciblée à une fonctionnelle pour la mécanique des fluides : Application à la prédiction haute-fidélité du bang sonique." Paris 6, 2008. https://tel.archives-ouvertes.fr/tel-00361961v2.
Hessian based unstructured mesh adaptation has already proved its efficiency to improve the ratio between solution accuracy and the number of degrees of freedom. However, when dealing with flows with shocks, several problematics occur : (i) a loss of convergence order generally due to the presence of steep gradients or genuine discontinuities in the flow, even if a provably spatially high order method is employed, (ii) error estimates may prescribe a size converging to zero in the discontinuity vicinity. These problems lead to the loss of anisotropy. We show that these problems can be solved by using a particular multi-scales mesh adaptation procedure based on a continuous mesh model. With this approach, prescribing a minimal size is not required and anisotropy is fully preserved. Global second order mesh convergence is numerically observed even with flows with shocks. When more information is given (as the EDP or a functional output), hessian based mesh adaptation is no more optimal in the distribution of degrees of freedom in the computational domain. We address this issue by considering an a priori error estimate to control approximation error on functionals when the flow is governed by the Euler equations. This estimate allows us to derive an anisotropic mesh prescription. Finally, all adaptive strategies are applied to predict high-fidelity sonic boom signature of complex aircrafts
Guichard, Cindy. "Schémas volumes finis sur maillages généraux en milieux hétérogènes anisotropes pour les écoulements polyphasiques en milieux poreux." Phd thesis, Université Paris-Est, 2011. http://tel.archives-ouvertes.fr/tel-00674503.
Dumeau, Jean-Paul. "Contrôle et adaptation des maillages 3D : application à l'automatisation des calculs /." Cachan : Laboratoire de mécanique et technologie, 1995. http://catalogue.bnf.fr/ark:/12148/cb358148971.
Schmid, Quentin. "Modélisation du rayonnement thermique en immersion de volume." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM086/document.
For heating and quenching operations occurring during material forming processes, thermal radiation is the the predominant physical phenomenon. Hence, when one tries to simulate such processes, it is important to have at disposal powerful tools for the numerical modelling of thermal radiation.The numerical simulation of these processes often rises numerous problems and questions, as the representation of a complex environment, involving several components ( ingots, burners, nozzles, walls), to deal with different coupled physical phenomena ( flow, heat transfer, boiling, thermal radiation). In this regard, some “immersed” numerical methods, allows a generalist treatment of these different problems, have gained popularity and drag interest of the scientific community in the recent years.The Thost project, aiming to produce a software for heat transfer during material forming processes, fits in the framework, and this PhD is part of this project. The goal is therefore to design tools for numerical modelling of thermal radiation within the immersed volume method of the Thost software. Two approaches are presented: one consisting in the adaptation of an existing method to the context of the immersed volume method, another concerning the development of a formulation for a specific model of radiation. These methods are then tested on industrial applications provided by our partners
Sarkis, Carole. "Modélisation de la solidification dendritique d’un alliage Al-4.5%pdsCu atomisé avec une méthode de champs de phase anisotrope adaptative." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM048/document.
Dendritic growth is computed using a phase-field model with automatic adaptation of an anisotropic and unstructured finite element mesh. Unknowns are the phase-field function, a dimensionless temperature and a dimensionless composition, as proposed by [KAR1998] and [RAM2004]. Linear finite element interpolation is used for all variables, after discretization stabilization techniques that ensure convergence towards a correct non-oscillating solution. In order to perform quantitative computations of dendritic growth on a large domain, two additional numerical ingredients are necessary: automatic anisotropic unstructured adaptive meshing [COU2011], [COU2014] and parallel implementations [DIG2001], both made available with the numerical platform used (CimLib) based on C++ developments. Mesh adaptation is found to greatly reduce the number of degrees of freedom. Results of phase-field simulations for dendritic solidification of a pure material and a binary alloy in two and three dimensions are shown and compared with reference work. Discussion on algorithm details and the CPU time are outlined and a comparison with a macroscopic model are made
Veysset, Jérémy. "Simulation des grands espaces et des temps longs." Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0083/document.
Fluid-Structure Interaction (FSI) describes a wide variety of industrial problems arising in mechanical engineering, civil engineering and biomechanics. In spite of the available computer performance and the actual maturity of computational fluid dynamics and computational structural dynamics, several key issues still prevent accurate FSI simulations.Two main approaches for the simulation of FSI problems are still gaining attention lately: partitioned and monolithic approaches. Results in the literature show that the partitioned approach is accurate and efficient but some instabilities may occur depending on the ratio of the densities and the complexity of the geometry. Monolithic methods are still of interest due to their capability to treat the interaction of the fluid and the structure using a unified formulation. In fact it makes the build up of a FSI problem easier as the mesh do not have to fit the geometry of the solids and the transfers are treated naturally.The software Thost has been created based on these analyzes. Thost is a 3D aerothermal numerical software. It has been developped for the numerical simulation of industrial processes like the heating in industrial furnaces as well as quenching. Its target is to model numericaly the thermal history of the industrial pieces in their environment without using any transfer coefficient. However the computational costs are still high and therefore the software is not fully efficient from an industrial point of view to simulate, analize and improve complex processes. All the work in this PhD thesis has been done to reduce the computational costs and optimize the accuracy of the simulations in Thost based on innovatives numerical methods such as dynamic anisotropic mesh adaptation, stabilized finite elements methods and immersing the objects directly from their Computer Aided Design files
Bigot, Erwan. "Simulation tridimensionnelle du remplissage de corps minces par injection." Phd thesis, École Nationale Supérieure des Mines de Paris, 2001. http://tel.archives-ouvertes.fr/tel-00275305.
Grenier, Gauthier Vincent. "Adaptation de maillage hiérachique pour des problèmes singuliers." Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26503.
Turgeon, Daniel. "Adaptation de maillages et étude d'un estimateur d'erreur a posteriori pour les fluides viscoélastiques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61364.pdf.
Wane, Bocar Amadou. "Adaptation de maillages et méthodes itératives avec applications aux écoulements à surfaces libres turbulents." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29353/29353.pdf.
Bigot, Erwan. "Simulation tridimensionnelle du remplissage de corps minces par injection." Paris, ENMP, 2002. http://www.theses.fr/2002ENMP1073.
Viville, Quentin. "A method of hp-adaptation for Residual Distribution schemes." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0408/document.
This thesis presents the construction of a p-adaptive Residual Distribution scheme for the steady Euler equations and a hp-adaptive Residual Distribution scheme for the steady penalized Navier-Stokes equations in dimension two and three. The Euler and Navier-Stokes equations are recalled along with their non dimensional versions. The basis definitions and properties of the steady Residual Distribution schemes are presented. Then, the construction of a p-adaptive Residual Distribution scheme for the Euler equations is considered. The construction of the p-adaptive scheme is based upon the expression of the total residual of an element of a given degree k (in the Finite Element sense) into the total residuals of its linear sub-elements. The discrete solution obtained with the p-adaptive scheme is then a one degree polynomial in the divided elements and a k-th degree polynomial in the undivided ones. Therefore, the discrete solution is in general discontinuous at the interface between a divided element and an undivided one. This is in apparent contradiction with the continuity assumption used in general to demonstrate the discrete Lax-Wendroff theorem for Residual Distribution schemes. However, as we show in this work, this constrain can be relaxed. The consequence is that if special quadrature formulas are employed in the numerical implementation, the discrete Lax-Wendroff theorem can still be proved, which guaranties the convergence of the p-adaptive scheme to a weak solution of the governing equations. The formulas that express the total residual into the combination of the total residuals of the sub-elements are central to the method. In dimension two, the formula is obtained with the classical Lagrange basis in the quadratic case and with the Bézier basis in dimension three. These two formulas are then generalized to arbitrary polynomial degrees in dimension two and three with a Bézier basis. In the second part of the thesis the application of the p-adaptive scheme to the penalized Navier-Stokes equations with anisotropic mesh adaptation is presented. In practice, the p-adaptive scheme is used with the IBM-LS-AUM (Immersed Boundary Method with Level Sets and Adapted Unstructured Meshes) method. The IBM-LS-AUM allows to impose the boundary conditions with the penalization method and the mesh adaptation to the solution and to the level-set increases the accuracy of the representation of the surface and the solution around walls. When the IBM-LSAUM is combined with the p-adaptive scheme, it is possible to use high-order elements outside the zone where the penalization is applied. The method is robust as shown by the numerical applications at low to large Mach numbers and at different Reynolds in dimension two and three
Colson, Marie-Hélène. "Adaptation de maillages éléments finis volumiques et surfaciques à partir d'un calcul d'erreur de discrétisation." Nancy 1, 1997. http://www.theses.fr/1997NAN10256.