Literatura académica sobre el tema "Simulation aux grandes échelles de tourbillons"
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Tesis sobre el tema "Simulation aux grandes échelles de tourbillons"
Moldoveanu, Cristian-Emil. "Simulation aux Grandes Échelles de tourbillons longitudinaux soumis à une turbulence extérieure intense". Toulouse, INPT, 2007. http://ethesis.inp-toulouse.fr/archive/00000696/.
Texto completoThe aim of this thesis is to study the behavior of the vortices under the influence of an external turbulence. We present the main mechanisms of instability, which is the basis of the counter-rotating vortices longitudinal decay. For the simulations we have selected the software JADIM developed by IMFT, adapted for Large Eddy Simulation of the turbulent flows. The validation of the numerical methods and of the software used, is made by comparing the theoretical and the numerical results of a single longitudinal vortex flow, in absence of external disturbances. We studied the behavior of a perturbed flow to the interior or to the exterior of a vortex. The study of the effect of the external turbulence on a counter-rotating longitudinal vortices pair highlighted the competition between elliptical and Crow instability. The simulation of the vortices pair in ground effect highlighted the generation mechanism of a vorticity layer and the generation of the secondary vortices
Bénard, Pierre. "Analyse et amélioration d'une chambre de combustion centimétrique par simulations aux grandes échelles". Thesis, Rouen, INSA, 2015. http://www.theses.fr/2015ISAM0018/document.
Texto completoDesigning a meso-scale combustion system remains a challenging scientific and technological issue. Increasing the surface-to-volume ratio promotes wall heat losses, reduces the residence time and turbulence intensity. The main objective of this thesis is to understand the physical phenomena involved in the centimetre-sized asymmetric whirl cubic burner of 8 x 10 x 8 mm3 (millimètre cube) and develop specific adapted numerical tools. The methane/air reactive flow is studied using detailed LES. While fuel and air are injected separately, combustion takes place in the premixed regime. However combustion is far from being complete, causing low combustion efficiency and significant emissions of pollutants. The second objective is to adapt in the best possible way the performances of this burner. Hydrogen enrichment of the fuel mixture showed significant efficiency enhancement and reduced pollutant emissions. Several other combustor geometries are also studied, paving the way for future improvement
Grébert, Arnaud. "Simulation numérique aux grandes échelles du contrôle de l'interaction onde de choc/couche limite au moyen de micro-générateurs de vortex". Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0046.
Texto completoBecause it is ubiquitous in high Mach number internal and external flow of interest in aeronauticalapplications, shock wave/turbulent boundary layer interaction (SBLI) is characterised by alow-frequency unsteadiness which generates large wall-pressure fluctuations that can occur at theresonant frequency of the structures. This work is devoted to the study of passive flow controldevices such as microramp vortex generators (mVGs) to alleviate these detrimental effects of SBLI.Large-eddy simulations (LES) have been performed based on an experimental configurationby Wang et al. (2012) of a SBLI under the influence of microramps at a Mach number ofM = 2.7 and a Reynolds number of Re× = 3600. The use of microramps has been shown toenable a reorganisation of the recirculation zone by breaking the spanwise homogeneity of theinteraction, yielding to a change of the reflected shock foot back and forth motion along the span.Additional simulations on three new configurations allowed to assess the effectiveness of microrampsin controlling the SBLI by comparing reduced size mVGs with more conventional ones
Maurel, Stéphane. "Étude par imagerie laser de la génération et de la rupture d'un écoulement tourbillonnaire compressé : situation modèle pour la validation de simulations aux grandes échelles dans les moteurs". Toulouse, INPT, 2001. http://www.theses.fr/2001INPT035H.
Texto completoLumet, Eliott. "Évaluation et réduction des incertitudes pour la simulation numérique de la dispersion atmosphérique à micro-échelle". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES003.
Texto completoAir quality is severely degraded during events such as industrial accidents. Harmful gases and particles are released into the atmosphere and carried by the wind. In built environments, these pollutants can lead to local pollution peaks due to buildings blocking the flow, resulting in short-term health and environmental risks. Locating these peaks requires the use of models solving the fundamental equations of fluid dynamics and their interactions with the built environment. Despite their complexity, these models are subject to uncertainties that are partly linked to atmospheric conditions. The aim of this thesis is to build and validate a modeling system able of estimating these uncertainties and identifying possible dispersion scenarios. This is achieved by using tools derived from statistical learning and by informing the model with in-situ observations
Pinon, Grégory. "Modélisation numérique de jets transverses : application aux cas des inverseurs de poussée d'un avion en phase d'atterrissage". Le Havre, 2005. http://www.theses.fr/2005LEHA0057.
Texto completoThe aim of this PhD study is to predict the thrust reversers jets trajectories. These devices equip the aircrafts and produce opposite thrust, which brakes the aircraft in landingphase. The flow is ejected from the thrust reversers in a jet like form. This flow is complex and the mains characteristics are present even on a long distance from the nozzle's exit. For this study, we chose the vortex method more especially its « vortex blob » version. The resolution is unsteady and the discretisation is confined to the vortical zones. These zones are represented by vortex particles, carrying vortical information and followed in the flow in a lagrangian way. First, we make a short review of most jet like flows and we focus on their main characteristics, especially form jet issuing from a nozzle into a crossflow, where a contra-rotating vortex pair appears and is long-lived. Vortical structures are numerous in these kind of flow and they mostly depend on the injection ratio (ratio of the jet velocity compared to crossflow velocity). Secondly, treat the numerical aspects of the vortex method method. We use a three-dimensional Vortex Blob method, on which we have implemented a « Tree code » algorithm, a global reggridding of the flow and a « Particle strength Exchange » diffusion scheme, which unables us to use a Large Eddy Simulation (LES) model. On top of that, the whole code is parallelised using the MPI libraries. Then, we present some academical results of crossflow jet simulations. Nous study the temporal evolution of the vortical structures depending on the injection ratio, the temporal evoltion of the jet exit velocity, etc. . . Finally, we present a new hybrid method which couples eulerian simulations to our langrangian simulations in order to treat the industrial flow configurations. After some validation aspects of the new hybrid method with domain decomposition, we present several « complete » simulations of an aircraft in a landing phase. Finally, we are able to distingish re-ingestion case as they were experimentally obersed during wind tunnel testings
Guedot, Lola. "Développement de méthodes numériques pour la caractérisation des grandes structures tourbillonnaires dans les brûleurs aéronautiques : application aux systèmes d'injection multi-points". Thesis, Rouen, INSA, 2015. http://www.theses.fr/2015ISAM0017/document.
Texto completoThe reduction of pollutant emissions of aeronautical devices requires to optimize the design of the injection systems in the combustion chamber. The objective of this work is to improve the understandingof the flow dynamics in swirl stabilized burners. Large Eddy Simulation has become a major tool for the analysis of such flows. The steady increase in computational power enables to perform high-fidelity simulations, that generates a large amount of data, making it difficult to extract relevant information regarding the large scale phenomena. To this aim, massively parallel post-processing methods, suited for complex geometries, were developed in order to extract large-scale structures in turbulent flows. These methods were applied to simulations of spray flames in swirl burners, to get a better insight of how the large scale structures interact with the flame topology and the spray dynamics
Séverac, Eric. "Simulation des grandes échelles de haute précision d'écoulements tournants avec parois". Aix-Marseille 3, 2008. http://www.theses.fr/2008AIX30024.
Texto completoFully three-dimensional Large Eddy Simulation (LES) is developed with spectral approximation using a Spectral Vanishing Viscosity (SVV) technique. The SVV is first shown to keep the accuracy of the approximation. Secondly, turbulent flows are studied in an actual enclosed rotor-stator configuration. At low Reynolds number, we use a Direct Numerical Simulation (DNS) as reference. Then at Higher Reynolds number (from 10^5 to10^6), we provide detailed data on the flow and its boundary layer, including structures, physical properties, and statistical data. The results are favorably compared with the literature and an experiment conducted on an identical apparatus. We conclude that the SVV, coupled with a high order approximation, succeed in computing LES of complex flows when classical LES models fail
Albouze, Guillaume. "Simulation aux grandes échelles des écoulements réactifs non prémélangés". Phd thesis, Toulouse, INPT, 2009. http://oatao.univ-toulouse.fr/7796/1/albouze.pdf.
Texto completoQuillatre, Pierre. "Simulation aux grandes échelles d'explosions en domaine semi-confiné". Phd thesis, Toulouse, INPT, 2014. http://oatao.univ-toulouse.fr/11851/1/quillatre.pdf.
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