Dissertationen zum Thema „Maillage en blocs structurés“
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Calderan, Simon. „Génération interactive de maillages hexaédriques structurés par blocs“. Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG049.
Der volle Inhalt der QuelleThe numerical simulation codes based on element and finite volume methods require discretizing the studied domain - for example a mechanical part such as a motor, an airplane wing, a turbine, etc. - using a mesh. In 3 dimensions, a mesh is a set composed of simple volumic elements, most often tetrahedrons or hexahedra, which partition the field of study. The choice of tetrahedrons or hexahedra is mainly dictated by the application (fluid-structure interaction, hydrodynamics, etc.). If the automatic generation of tetrahedral meshes is a relatively controlled process today, generating hexahedral meshes is still an open problem. This is problematic for applications that just imperatively require hexahedral meshes since their generation is done semi-automatically, which can take several weeks to several months of engineer time! While the time devoted to the digital simulation process itself tends to decrease due to the power of the machines used, the bottleneck is now in the preparation of the data, namely to obtain a CAD model adapted to the computation, then generate a mesh.It is in this context that we propose to develop a hybrid approach combining:1. The development of (semi) -automatic algorithms for generating and modifying block-structured hexahedral meshes;2. The implementation of an interactive graphic software dedicated to the manipulation of block structures. The interaction mechanisms will also be used to guide the algorithms in their decision-making, whether at initialization (criteria to be affixed to particular CAD entities) or in the course of an algorithm (decision between several options on which the algorithm cannot pronounce itself).The objective of this thesis is therefore not to provide a universal automatic solution, which seems unattainable at present, but rather to reduce the engineering time devoted to the generation of the mesh by providing more adapted tools. In this context, we propose to place the study as an extension of [LED10, KOW12, GAO15, GAO17], which considered the problem of simplification and enrichment of hexahedral meshes by insertion and removal of mesh layers. In all these works, the proposed algorithms are simple 'greedy' algorithms where the mesh is modified step by step to converge towards a final solution Ef: At each step Ei, one makes the hypothesis that the 'best' solution Ef will be obtained by making the 'optimal' choice for Ei. However, in operational research, such an approach is known to be perfectible since the problem of optimization treated is nonlinear. The idea is to use usual approaches in operational research and more specifically multi-agent systems, coupled to interactive tools, to allow the generation of block structures on complex CA0s
Postat, Valentin. „Représentation et optimisation de maillage structuré par blocs à l'aide de systèmes multi-agents“. Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASG003.
Der volle Inhalt der QuelleThis thesis deals with the representation and generation of block-structured hexahedral meshes. To date, there is no method for generating satisfactory block structures for any geometric domain. In practice, expert engineers generate these meshes using interactive software, which can take several weeks to complete. Moreover, adding modification operations in these interactive softwares is a delicate task to maintain the coherence of the block structure and its relationship with the geometric domain to be discretized. In order to improve this process, we first propose to define hexahedral mesh manipulation operations based on the use of the generalized map model. Then, by considering block structures obtained using the Polycube method, we provide methods for optimizing the topology of these structures to satisfy constraints of a geometric nature. We propose a first method in dimension 2, which considers a local approach to the problem based on the experience of engineers working with interactive software. We then propose a second method, this time using ant colony optimization meta-heuristics for leaf selection in dimension 3
Dotse, Kokou Michaelis. „Création de maillages quadrilatéraux bloc structurés à partir de champ de croix prescrit et respectant les caractéristiques physiques d'une scène de calcul“. Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0027.
Der volle Inhalt der QuelleThe objective of this thesis is to provide new solutions to improve performance in the numerical solution of partial differential equations by studying a method for generating quadrilateral meshes based on cross-field techniques.Our approach relies on aligning a given cross field with the boundary of the computational domain, followed by partitioning the domain into four-sided regions which are then meshed into quadrilaterals. This allows us to generate a structured block mesh while preserving the positions of the singularities of the initial cross field. To achieve this, we conduct a theoretical study of cross fields to identify the conditions under which a given cross field effectively partitions and meshes the domain on which it is defined.This method is initially presented for simply connected domains and then extended to non-simply connected domains. It allows us to handle domains consisting of multiple materials as well as boundary singular points, which in practice delineate portions of the domain boundary to account for mixed boundary conditions in numerical simulations. Finally, we discretize the method on triangular meshes and propose a generalization to curved surfaces in space
Romé, Christophe. „Une méthode de raccordement de maillages non-conformes pour la résolution des équations de Navier-Stokes“. Bordeaux 1, 2006. http://www.theses.fr/2006BOR13175.
Der volle Inhalt der QuelleRome, Christophe. „Une méthode de raccordement de maillages non-conformes pour la résolution des équations de Navier-Stokes“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2006. http://tel.archives-ouvertes.fr/tel-00126917.
Der volle Inhalt der Quelleobtenus montrent la faisabilité et le bien-fondé de l'approche proposée.
Famy, Carine. „Les termes d'échange entre blocs et fractures dans les simulateurs de réservoirs fracturés“. Phd thesis, Toulouse, INPT, 2006. http://oatao.univ-toulouse.fr/7573/1/famy.pdf.
Der volle Inhalt der QuelleLorendeau, Benjamin. „Amélioration des performances via un parallélisme multi-niveaux en maillage sur un code de CFD en maillages non structurés“. Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0412.
Der volle Inhalt der QuelleThe ever-evolving and ultimately complexification of computer architectures enforce scientific developpers to maintain both their software and technical knowledge in order to pertain their ability to fully exploit recent high performance computing platforms. Moreover the birth of heterogeneous plateforms and the large increase in core number per processor lead developpers of software parallelized through distributed paralleslim to see a small but consistent decrease of performance on recent plateforms. For cs, the transission from a full MPI code to a MPI+OpenMP code is not fully satisfying and cannot adress the scalability issue that alack of load balancing causes. This load balancing issue is a complex problemto solve for a code such as cs where partitionning is a NP problem and mustdata being indexed due to the unstructured nature of the meshes used. To solvethis kind of issue and many others (such as portability and heterogeneity), the use of a task based runtime recently won popularity through three different ways: loop parallelism, sequential submission of task(STF) or parameterized task graph (PTG). This thesis is focused on the transition effort of cs, a computational fluid dynamic (CFD) code with unstructured meshes (sparse linear algebra) from a mostly distributed parallelism to the integration of a task based runtime. In order to do this,we investigated the STF and PTG paradigms through the use of StarPU and PaRSECin cs. We demonstrate their advantages over a solution such that MPI + OpenMP as well ascompare their use in terms of complexity and performance with the existing solutions in cs. This thesis was made through the collaboration between the MFEE department of EDF R&D and the Tadaam research team, grouping Inria Bordeaux Sud-Ouest, the LaBRI,University of Bordeaux 1 and Bordeaux INP
Zaytsev, Victor. „Méthodes stochastiques pour la modélisation d'incertitudes sur les maillages non structurés“. Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM094/document.
Der volle Inhalt der QuelleSimulations of physical phenomenon often require discretizing the medium with a mesh. An example of this type of simulation is the simulation of fluid flow through a porous medium and the evaluation of the geomechanical stress in the petroleum reservoir. The studied medium is often not homogeneous and applying a homogeneity hypothesis can lead to incorrect simulation results. That makes simulation of heterogeneities important for this kind of problems.This thesis is devoted to geostatistical simulations of heterogeneities on unstructured grids using methods of non-linear geostatistics. The objective of this work is the development of algorithms for simulating heterogeneities directly on unstructured grids without using intermediate fine scale regular grids and upscaling. We present two theoretical models for geostatistical simulations of continuous parameters on unstructured grids which are different generalizations of the Discrete Gaussian model (DGM) – DGM 1 and DGM 2. The proposed theoretical models enable converting the problem of geostatistical simulation on an unstructured grid into the well-studied problem of simulating multivariate Gaussian random vectors followed by application of block-dependent transformation functions. The problem of simulating facies is also addressed in this work, for which generalizations of pluri-Gaussian and truncated Gaussian simulation models for unstructured grids are proposed.An application of the proposed methods is demonstrated on a case study X, which is an offshore gas reservoir with a tartan-meshed grid
Thebault, Loïc. „Algorithmes Parallèles Efficaces Appliqués aux Calculs sur Maillages Non Structurés“. Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV088/document.
Der volle Inhalt der QuelleThe growing need for numerical simulations results in larger and more complex computing centers and more HPC softwares. Actual HPC system architectures have an increasing requirement for energy efficiency and performance. Recent advances in hardware design result in an increasing number of nodes and an increasing number of cores per node. However, some resources do not scale at the same rate. The increasing number of cores and parallel units implies a lower memory per core, higher requirement for concurrency, higher coherency traffic, and higher cost for coherency protocol. Most of the applications and runtimes currently in use struggle to scale with the present trend. In the context of finite element methods, exposing massive parallelism on unstructured mesh computations with efficient load balancing and minimal synchronizations is challenging. To make efficient use of these architectures, several parallelization strategies have to be combined together to exploit the multiple levels of parallelism. This P.h.D. thesis proposes several contributions aimed at overpassing this limitation by addressing irregular codes and data structures in an efficient way. We developed a hybrid parallelization approach combining the distributed, shared, and vectorial forms of parallelism in a fine grain taskbased approach applied to irregular structures. Our approach has been ported to several industrial applications developed by Dassault Aviation and has led to important speedups using standard multicores and the Intel Xeon Phi manycore
Joseph, David. „Modélisation des transferts radiatifs dans les systèmes en combustion par méthode aux ordonnées discrètes sur des maillages non structurés tridimensionnels“. Phd thesis, Toulouse, INPT, 2004. http://ethesis.inp-toulouse.fr/archive/00000016/.
Der volle Inhalt der QuelleBotella, Arnaud. „Génération de maillages non structurés volumiques de modèles géologiques pour la simulation de phénomènes physiques“. Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0097/document.
Der volle Inhalt der QuelleThe geomodeling main goals are to represent and understand the subsurface. The geological structures have an important role for understanding and predicting its physical behavior. We defined a geological model as a set of structures and their connections. The meshes are numerical supports to solve the equations modeling the subsurface physics. So it is important to build a mesh representing a geological model to take into account the impact of these structures on the subsurface phenomena. The objective of this thesis is to develop volumetric meshing methods for geological models. We propose a volumetric unstructured meshing method to build two mesh types: an adaptive tetrahedral mesh and an hex-dominant mesh (i.e. made of tetrahedra, triangular prisms, quadrilateral pyramids and hexahedra). This method generates first a tetrahedral mesh that can respect different types of data: (1) a geological model defined by its boundaries to capture the structures in the volumetric mesh, (2) well paths represented as a set of segments, (3) a mesh size property to control the mesh element edge length and (4) a direction field to control vertex/element alignments inside the mesh to increase some features such as elements with right angles. Then, this tetrahedral mesh can be transformed in a mixed-element mesh. The method recognizes combinatorial relationships between tetrahedra to identify new elements such as prisms, pyramids and hexahedra. This method is then used to generate meshes whose features correspond to a given application in order to reduce errors during numerical computation. Several application domains are considered such as geomechanical, ow and wave propagation simulations
Moulard, Laurence. „Optimisation de maillages non structurés : applications à la génération, à la correction et à l'adaptation“. Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10173.
Der volle Inhalt der QuelleUne étude théorique introduit de nouveaux objets, les tétraphores réalisables, en considérant les seules conditions topologiques d'un maillage. Ces objets se construisent facilement à partir de la frontière du domaine à mailler ; il suffit d'ajouter des contraintes géométriques, très simples à tester et pouvant se traduire sous la forme d'un critère à optimiser, pour obtenir un maillage. Des opérations transformant ces tétraphores sont définies. Les algorithmes d'optimisation sont ainsi bien plus efficaces car ils peuvent être appliques sur un ensemble plus vaste que les maillages
Les algorithmes décrits dans cette thèse sont utilisés industriellement. Des résultats sont donnes pour l'optimisation selon des critères géométriques et topologiques, l'adaptation selon un critère de densité, la correction après déformation des frontières et la génération de maillages
Saint-Aubin, Karell. „Etude de dispersions de nanotubes de carbone par des polymères pour l'élaboration de composites conducteurs et structurés“. Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-00583931.
Der volle Inhalt der QuelleEscalé, Pierre. „Elaboration de films nid d'abeille hiérarchiquement structurés à partir de copolymères : synthèse, structuration et propriétés de surface“. Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3027/document.
Der volle Inhalt der QuelleThe present studies aim at designing hierarchically structured porous surface from copolymers with well defined structures. As a science in constant evolution, polymer chemistry, enable the synthesis of diblock copolymers with different natures by the mean of various radical controlled polymerization techniques. Indeed, radical controlled polymerization with nitroxyde (NMP), by atom transfer (ATRP), by reversible addition/fragmentation transfer (RAFT) or by Cu(0) were used for the synthesis of diblock copolymers based on polystyrene and different acrylates or 4-vinylpyridine blocks. The intimately association between a fast solvent evaporation process named the Breath Figure and the synthesis of the copolymers enable the production of hierarchically structured materials from micro to nanoscale. The nature of the different blocks confers adhesion, wettability or bioactivity properties to these materials. These researches benefit from the chemistry and physico-chemistry laboratory competences. Indeed, microscopy techniques (optical, atomic force and electronic), scattering (small angle neutron or X-ray) as well as tack or wettability measurements enable the complete characterization of films structuration and point up their properties
Saint-Aubin, Karell. „Etude de dispersions de nanotubes de carbone par des polymères pour l’élaboration de composites conducteurs et structurés“. Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14021/document.
Der volle Inhalt der QuelleThis thesis deals with the study of carbon nanotube dispersions by polymers, the processing of composite films and the study of their mechanical and electrical properties. The first part of the work focuses on the use of poly(acrylic) acid (PAA), which proves to be an excellent dispersing agent in water. A study of the interactions between the PAA and the nanotubes is realised, tuned by the pH conditions. The fabrication of composite films, for future applications in the field of conductive inks and paints, shows that a fine control of the PAA adsorption and the dispersion stability allows the formation of homogeneous and conductive composites. In a second part, nanotube composites are elaborated from a block copolymer, the SBM, well-known for its remarkable self organization properties. Interestingly, the copolymer is at the same time the nanotube dispersing agent in the solvent and the structuring matrix of the final composite. This thesis shows that the copolymer structure, which strongly depends on the solvent used, influences the mechanical properties of composite films, and that the addition of nanotubes noticeably improves the performances
Viallix, Anne. „Simulation de la structure de parois dans un matériau magnétique“. Grenoble INPG, 1990. http://www.theses.fr/1990INPG0029.
Der volle Inhalt der QuelleDapogny, Charles. „Optimisation de formes, méthode des lignes de niveaux sur maillages non structurés et évolution de maillages“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00916224.
Der volle Inhalt der QuelleAnsanay-Alex, Guillaume. „Un schéma éléments finis non-conformes / volumes finis pour l'approximation en maillages non-structurés des écoulements à faible nombre de Mach“. Phd thesis, Université de Provence - Aix-Marseille I, 2009. http://tel.archives-ouvertes.fr/tel-00483598.
Der volle Inhalt der QuelleParisot, Martin. „Modelisation Intermediaire entre Equations Cinetiques et Limites hydrodynamiques : Derivation, Analyse et Simulations“. Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2011. http://tel.archives-ouvertes.fr/tel-00793342.
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