Дисертації з теми "PIC numerical simulations"
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Faugier, Loreline. "Modeling airflow related to train movement in subway stations : small-scale model and numerical simulations compared to on-site measurements." Electronic Thesis or Diss., La Rochelle, 2023. http://www.theses.fr/2023LAROS022.
Повний текст джерелаAir quality and ventilation efficiency in underground subway stations are concerns for health and safety. The piston effect, caused by trains passing through the station, contributes significantly to air movements. Models are often used to study and predict airflow in these environments due to challenges in on-site measurements. However, the differences between measured and modeled data are rarely discussed. This thesis focuses on developing models for train-induced airflow on platforms of underground subway stations. A 3D Computational Fluid Dynamics (CFD) model with a dynamic mesh is implemented to simulate the station. A small-scale model at 1:95 scale with Particle Image Velocimetry (PIV) is also used. Both models include the train's realistic movement, deceleration, stop, and departure phases. To validate the models, extensive on-site measurements are conducted, recording velocity magnitude at various platform positions. The results are compared using correlation and peak shape parameters. They show that models can capture the key elements of piston wind in the station: both the numerical and experimental results reveal that differences can be found between locations close to each other, that are the consequence of flow features developing at a fraction of the platform scale in the horizontal plane; and that local velocity changes occur over short time intervals scaling with the train velocity. However, finer predictions about the value of velocity magnitude are less reliable as they are bounded by simplifications of the geometry, of the boundary conditions and by scaling considerations. Despite these limitations, the models provide insights into flow patterns and are used to investigate how changes in station blockage ratio and train speed affect velocity magnitude and air exchanges in the station. The study concludes that the models are valuable tools for exploring platform airflow, but caution is needed in interpreting fine-scale velocity predictions
Denoual, Emilien. "Rayonnement térahertz par interaction laser-solide en régime relativiste." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP166.
Повний текст джерелаThe terahertz (THz) domain is attracting increasing interest for its promising applications in various sectors of research and industry, including molecular spectroscopy, medical imaging, homeland security, condensed matter studies, and materials science. Progress in these fields is rapid and largely stimulated by the development of new high-power radiation sources. Relativistic laser-solid interaction, hitherto primarily exploited for its strong radiative potential in the highest parts of the electromagnetic spectrum, constitutes a promising approach for generating intense THz pulses spanning broad frequency bands. This thesis is first devoted to the theoretical and numerical study of the two main THz emissive mechanisms occurring during such interactions: the coherent transition radiation (CTR) of hot electrons ejected from the plasma after being accelerated by the ultra-intense laser pulse field, and the plasma expansion radiation (PER) occurring over longer time scales. We develop a semi-analytical model of radiation due to fast electrons, taking into account their trajectory in the restoring spacecharge electric field they induce at the target surface. Their complete radiation then results from the interference of CTR and synchrotron/bremsstrahlung-type emission. Parametric studies on the characteristics of the laser pulse and the target allow us to establish configurations that maximize this radiation. The latter proves to be very sensitive to the fraction of escaping electrons. In addition, we describe the radiation associated with the plasma expansion by considering the unidirectional model, taking into account various effects related to the finite thickness of the foil and the multidimensional geometry of the accelerating field. For a femtosecond laser pulse and a micrometer-thick target, we anticipate a net THz radiation largely dominated by electron radiation, thus establishing a hierarchy of THz emission mechanisms in the context of laser-thin foil interaction. Finally, to test these theoretical models, we implement a far-field radiation algorithm in the "particle-in-cell" (PIC) code CALDER. Validated in simple cases and then applied to beam-plasma and laser-solid interaction simulations, this module provides the first "ab initio" description of low-frequency radiation in the framework of PIC simulations
Lutz, Mathieu. "Etude mathématique et numérique d'un modèle gyrocinétique incluant des effets électromagnétiques pour la simulation d'un plasma de Tokamak." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD036/document.
Повний текст джерелаThis thesis is devoted to the study of charged particle beams under the action of strong magnetic fields. In addition to the external magnetic field, each particle is submitted to an electromagnetic field created by the particles themselves. In kinetic models, the particles are represented by a distribution function f(x,v,t) solution of the Vlasov equation. To determine the electromagnetic field, this equation is coupled with the Maxwell equations or with the Poisson equation. The strong magnetic field assumption is translated by a scaling wich introduces a singular perturbation parameter 1/ε
Wahba, Essam Moustafa. "Hierarchical formulations for numerical flow simulations /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
Повний текст джерелаCharoy, Thomas. "Numerical study of electron transport in Hall thrusters." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX046.
Повний текст джерелаIn the last decade, the number of satellites orbiting around Earth has grown exponentially. Thanks to their low propellant consumption, more and more electric thrusters are now used aboard these satellites, with the Hall thrusters being one of the most efficient. From the diversity of applications stems the need of widening the thruster power capabilities. However, due to a lack of knowledge on Hall thruster physics, this scaling is currently done empirically, which limits the efficiency of the newly developed thrusters and increases the development time and cost. To overcome this issue, numerical models can be used but a deeper understanding on key phenomena is still needed, more specifically on the electron anomalous transport which should be self-consistently accounted for to properly capture the discharge behaviour.As this transport is related to the azimuthal electron drift instability, an existing 2D Particle-In-Cell code was further developed to simulate this azimuthal direction along with the axial direction in which the ions are accelerated, producing the thrust. Prior to analyse the discharge behaviour, this code has been verified on a benchmark case, with 6 other PIC codes developed in different international research groups. This simplified case was later used to stress-test previous analytical developments to approximate the instability-enhanced electron-ion friction force which represents the contribution of the azimuthal instabilities to the anomalous transport. Then, the neutral dynamics has been included to capture the full self-consistent behaviour of the discharge. We used an artificial scaling technique, increasing the vacuum permittivity, to relax the PIC stability constraints and speed-up the simulations. Thanks to an efficient code parallelisation, we managed to reduce this scaling factor to a small value, hence simulating a case close to reality. The electron-ion friction force was found to be the main contributor to the anomalous transport throughout the whole low-frequency breathing mode oscillations. Finally, the complex interaction between the breathing mode, the ion-transit time instabilities and the azimuthal electron drift instabilities has been studied, with the formation of long-wavelength structures associated with an enhanced anomalous transport
Rogers, Tamara M. "Numerical simulations of convection, overshoot, and gravity waves in the sun /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
Повний текст джерелаIkram, M. "Radio-frequency generation of an electron plasma in a Malmberg-Penning trap and its interaction with a stationary or pulsed electron beam." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/233616.
Повний текст джерелаBerton, Stefano. "Numerical simulation of the durability mechanics of cement-based materials /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
Повний текст джерелаVedin, Jörgen. "Numerical modeling of auroral processes." Doctoral thesis, Umeå University, Physics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1117.
Повний текст джерелаOne of the most conspicuous problems in space physics for the last decades has been to theoretically describe how the large parallel electric fields on auroral field lines can be generated. There is strong observational evidence of such electric fields, and stationary theory supports the need for electric fields accelerating electrons to the ionosphere where they generate auroras. However, dynamic models have not been able to reproduce these electric fields. This thesis sheds some light on this incompatibility and shows that the missing ingredient in previous dynamic models is a correct description of the electron temperature. As the electrons accelerate towards the ionosphere, their velocity along the magnetic field line will increase. In the converging magnetic field lines, the mirror force will convert much of the parallel velocity into perpendicular velocity. The result of the acceleration and mirroring will be a velocity distribution with a significantly higher temperature in the auroral acceleration region than above. The enhanced temperature corresponds to strong electron pressure gradients that balance the parallel electric fields. Thus, in regions with electron acceleration along converging magnetic field lines, the electron temperature increase is a fundamental process and must be included in any model that aims to describe the build up of parallel electric fields. The development of such a model has been hampered by the difficulty to describe the temperature variation. This thesis shows that a local equation of state cannot be used, but the electron temperature variations must be descibed as a nonlocal response to the state of the auroral flux tube. The nonlocal response can be accomplished by the particle-fluid model presented in this thesis. This new dynamic model is a combination of a fluid model and a Particle-In-Cell (PIC) model and results in large parallel electric fields consistent with in-situ observations.
Chong, Antonio. "Numerical modelling and stability analysis of non-smooth dynamical systems vie ABESPOL." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231038.
Повний текст джерелаSpirkin, Anton M. "A three-dimensional particle-in-cell methodology on unstructured Voronoi grids with applications to plasma microdevices." Link to electronic dissertation, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050506-145257/.
Повний текст джерелаSeddighi-Moormani, Mehdi. "Study of turbulence and wall shear stress in unsteady flow over smooth and rough wall surfaces." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=166096.
Повний текст джерелаRevel, Adrien. "Modélisation des plasmas magnétisés. Application à l'injection de neutres pour ITER et au magnétron en régime impulsionnel haute puissance." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112083/document.
Повний текст джерелаA plasma is defined as a partially or completely ionized gas. Even though, they are very present in the visible universe, natural plasmas are rare on Earth. However, they are a major interest for industries and research institutes (surface treatment, spatial propulsion). Nevertheless, the understanding of plasma behavior is complicated because of the numerous physical fields involved. Moreover, theses plasmas can be magnetized, i.e., a magnetic field, external or induced, affects significantly the particle trajectories: r/L<1 where r is the Larmor radius and L the typical length of the system. This thesis is focused on the plasma modeling in two device: the accelerator of the ITER's neutral beam injector (NBI) and the magnetron in DC or HiPIMS regime. The feasibility of nuclear fusion on Earth is subject of numerous research around the world. Because of the energy necessary to get over the Coulomb barrier, the plasma must be confined. For ITER, the confinement is achieved by intense magnetic fields. However, to reach the required conditions of nuclear fusion reactions, especially in temperature, a high energy (1MeV) neutral beam injector is needed. The particle acceleration is a critical part in the creation of the neutral beam and it represents a technical challenge which is studied in this thesis work. The magnetron is an industrial process for creating thin film by physical sputtering. The ions created by a plasma discharge tear the atoms out of the cathode which are then deposited on the anode. The magnetic field created by permanent magnets trap the electrons near the cathode improving the process efficiency. The plasma behavior inside the magnetron is studied in direct and pulsed current as well as the appearance of self-organized structures in rotation around the magnetron axis. To study these devices, several program of numerical simulation have been developed. The Particle-In-Cell methode has been chosen because it takes into account, self-consistently, the space charge of the particules. Several techniques (null collision technique, Monte Carlo Collision, a posteriori Monte Carlo) and improvement (Non uniform mesh, third order charge projection) have been developed and implemented. Moreover, an original method, Pseudo 3D, allowing a three dimensional study of the magnetron, has been used with success. Finally, these programs have been parallelized to reduce the computation time
Odložil, Jan. "Tuhnutí odlitků ve skořepinových formách při odlévání ve vakuu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228718.
Повний текст джерелаSi-Ameur, Mohamed. "Simulations numériques de mélanges turbulents dans les écoulements cisaillés supersoniques." Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10214.
Повний текст джерелаBochu, Philippe. "Modélisation et simulation de la gravure chimique des monocristaux." Phd thesis, Université Joseph Fourier (Grenoble), 1995. http://tel.archives-ouvertes.fr/tel-00005029.
Повний текст джерелаBéreaux, Yves. "Simulation numérique d’écoulements de fluides viscoélastiques à formulation intégrale, par la méthode des tubes de courant." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0005.
Повний текст джерелаFallon, Benoit. "Simulation des grandes échelles d'écoulements turbulents stratifiés en densité." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0162.
Повний текст джерелаLamballais, Éric. "Simulations numériques de la turbulence dans un canal plan tournant." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0016.
Повний текст джерелаIncerti, Eric. "Synthèse de sons par modélisation physique de structures vibrantes : applications pour la création musicale par ordinateur." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0115.
Повний текст джерелаFerré, Giménez Ricardo. "Etude de nanoparticules magnétiques par simulation numérique." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10224.
Повний текст джерелаDeniset, François. "Modélisation numérique des conditions d'apparition de la cavitation de tourbillon marginal sur une aile-3D : effet de confinement." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0070.
Повний текст джерелаEl-Masri, Samir D. "Application de la méthode numérique TLM (transmission line matrix) aux ondes acoustiques et à la parole." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0129.
Повний текст джерелаKessler, Philippe. "Simulation des grandes échelles d’écoulements compressibles en géométrie complexe." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0201.
Повний текст джерелаPromayon, Emmanuel. "Modélisation et Simulation de la Respiration." Phd thesis, Université Joseph Fourier (Grenoble), 1997. http://tel.archives-ouvertes.fr/tel-00130070.
Повний текст джерелаDans une première partie les principes mécaniques du phénomène de la respiration sont exposés. Le problème apparaît alors comme la modélisation et la simulation comportementale sous contraintes d'un objet complexe composés de régions ayant des propriétés différentes (élasticité, motricité, rigidité). Les modèles générateurs basés sur la physique se révèlent être les outils informatiques les plus aptes à atteindre notre objectif. Un état de l'art de ces méthodes et des problématiques liées est alors dressé.
La deuxième partie présente la construction du modèle informatique découpée en régions de propriétés spécifiques. On présente alors une nouvelle fonction d'élasticité utilisant l'expression d'une mémoire de forme locale. Comparée à un modèle classique masse-ressort, cette fonction d'élasticité prouve son efficacité. La modélisation des régions musculaires et solides est ensuite présentée. Puis, on montre la possibilité de contraindre ces régions afin de modéliser d'autres propriétés. On développe notamment une méthode de résolution directe permettant de vérifier des contraintes locales et globales sans utiliser d'algorithme itératif. La résolution de la contrainte d'incompressibilité illustre cette méthode de résolution ; les principes généraux de cette résolution sont dégagés permettant ainsi de généraliser son application.
La dernière partie de ce manuscrit fournit une validation qualitative du modèle développé par l'intermédiaire de différents exemples, dont celui de la simulation des mouvements du tronc pendant la respiration.
Cortazar, Miguel Angel. "Le Cavermod, modèle physique de l'érosion de cavitation : qualification expérimentale et numérique." Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10089.
Повний текст джерелаMoinat, Philippe. "Application des techniques de simulation des grandes échelles à un écoulement en géométrie complexe : la marche en dérapage." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0141.
Повний текст джерелаGérard, Hervé. "Simulation de spectres de résonance magnétique nucléaire de cristaux liquides, polymères cristaux liquides et polymères conventionnels." Grenoble 1, 1993. http://www.theses.fr/1993GRE10144.
Повний текст джерелаPromayon, Emmanuel. "Modélisation et simulation de la respiration." Phd thesis, Grenoble 1, 1997. https://theses.hal.science/tel-00130070.
Повний текст джерелаBert, Paul-Frédéric. "Modélisation des écoulements instationnaires dans les turbomachines par une méthode éléments finis." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0218.
Повний текст джерелаMANSOURI, KACEM. "Etude theorique et experimentale du transfert de chaleur en regime periodique pour un ecoulement force a plan directeur." Nantes, 1995. http://www.theses.fr/1995NANT2085.
Повний текст джерелаBoillot, Benjamin. "Contribution à l'étude des écoulements turbulents en convection mixte." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10062.
Повний текст джерелаMahjoub, Fares. "Modélisation diphasique des évolutions transitoires d’interfaces liquide-gaz : application aux bulles attachées à des corps en mouvement." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0158.
Повний текст джерелаRen, Zhen. "Filtrage adaptatif appliqué au controle actif de l’acoustique d’une salle." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0188.
Повний текст джерелаBelhadri, Mansour. "Écoulements des fluides à seuil au travers de singularités convergentes et divergentes." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0002.
Повний текст джерелаHeiderich, Anne. "Diffusion multiple en milieu non linéaire ou anisotrope." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10200.
Повний текст джерелаCalvat, Pascal. "Mesure des observables de polarisation dans la photoproduction des mésons pseudoscalaires à GRAAL : préparation des programmes d'analyse et premiers résultats expérimentaux." Grenoble 1, 1997. http://www.theses.fr/1997GRE10005.
Повний текст джерелаNencib, Nadim. "Conception et validation d'un dispositif de caractérisation magnétique sous excitation bidimensionnelle : comportement des toles FeSi en champ tournant." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0109.
Повний текст джерелаRieu, Jean-Paul. "Contribution à l'étude de la fusion cristallisation des monocouches d'alcools courts à la surface de l'eau." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10207.
Повний текст джерелаCoacolo, Jean-Louis. "Etude de la dynamique de faisceaux courts d'électrons en début de ligne accélératrice du laser à électrons libres ELSA." Grenoble 1, 1993. http://www.theses.fr/1993GRE10133.
Повний текст джерелаGasser, Jean-Claude. "Études d'écoulements tournants : application à l'atomisation MHD." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0104.
Повний текст джерелаNeubrand, Anne Catherine. "Convection naturelle et ségrégation en solidification Bridgman sous champ magnétique." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0104.
Повний текст джерелаRouve, Laure-Line. "Prise en compte du comportement magnétique fréquentiel des tôles FeSi en modélisation électrotechnique." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0027.
Повний текст джерелаBaumgarten, Lars. "Gesteinsmechanische Versuche und petrophysikalische Untersuchungen – Laborergebnisse und numerische Simulationen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-202612.
Повний текст джерелаPauty, Emmanuel. "Étude du comportement inclusionnaire dans les écoulements d'aluminium liquide." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0115.
Повний текст джерелаHeude-Bonnet, Nathalie. "Optimisation de l'homogénéité de ventilation dans les batiments d'élevage : étude numérique et expérimentale." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0055.
Повний текст джерелаHiebel, Patrick. "Étude de paliers magnétiques supraconducteurs." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0012.
Повний текст джерелаFeuardent, Valérie. "Amélioration des modèles par recalage : application aux structures spatiales." Cachan, Ecole normale supérieure, 1997. http://www.theses.fr/1997DENS0019.
Повний текст джерелаJiang, Li. "Calcul en fatigue des ouvrages métalliques par la mécanique de la rupture (approche probabiliste)." Phd thesis, Ecole Nationale des Ponts et Chaussées, 1994. http://pastel.archives-ouvertes.fr/pastel-00569145.
Повний текст джерелаLin, Qun-Fu, and 林群富. "Simulations of seismic signals induced by landslides by numerical coupling of PFC and FLAC." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/54136855578701816025.
Повний текст джерела國立中興大學
水土保持學系所
101
A two-dimensional numerical coupling approach using the Particle Flow Code (PFC) and Fast Lagrangian Analysis of Continua (FLAC) code was developed to simulate the flow process of landslides and rock avalanches. The Xiaolin rock avalanche was used as a case study. The sliding of the rock fragments was simulated by PFC. When the rock fragments impact on the top boundary of FLAC, forces and velocities of the boundary grids were transmitted between the two codes. Monitoring locations were assigned in the coupled numerical model to record the seismic signals induced by the simulated rock avalanche. The time-frequency spectrograms of the seismic signals were analyzed using Hilbert-Huang transform (HHT) for examining the seismic characteristics. The simulated results were compared with the seismic signals recorded during the landslide from a broadband seismic station, SGSB, which is 11.4 km away from the Xiaolin landslide site. A rock-fall case was established using the same slope to simulate the signal induced by a single free falling rock. Monitoring locations were assigned in the coupled numerical model to record the seismic signals. The time-frequency spectrograms of the seismic signals were analyzed using HHT to examine the amplitudes of the seismic wave and the propagated velocities. The energy attenuation of the seismic wave versus distance and for different geological materials were analyzed.