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Visualization of two-phase flow dynamics: Techniques for droplet interactions, interfaces, and material transport / Grzegorz Karol Karch (2017)
Titre : Visualization of two-phase flow dynamics: Techniques for droplet interactions, interfaces, and material transport Type de document : Thèse/HDR Auteurs : Grzegorz Karol Karch, Auteur ; Thomas Ertl, Directeur de thèse ; H. Theisel, Directeur de thèse Editeur : Stuttgart : University of Stuttgart Année de publication : 2017 Importance : 180 p. Format : 21 x 30 cm Note générale : Bibliography
Von der Fakultät Informatik, Elektrotechnik und Informationstechnik und dem Stuttgart Research Centre for Simulation Technology der Universität Stuttgart zur Erlangung der Würde eines Doktors der Naturwissenschaften (Dr. rer. nat.), genehmigte AbhandlungLangues : Anglais (eng) Descripteur : [Termes IGN] analyse visuelle
[Termes IGN] mécanique des fluides
[Termes IGN] visualisation 4DIndex. décimale : THESE Thèses et HDR Résumé : (auteur) Computational visualization allows scientists and engineers to better understand simulation data and gain insights into the studied natural processes. Particularly in the field of computational fluid dynamics, interactive visual presentation is essential in the investigation of physical phenomena related to gases and liquids. To ensure effective analysis, flow visualization techniques must adapt to the advancements in the field of fluid dynamics that benefits substantially from the growing computational power of both commodity desktops and supercomputers on the one hand, and steadily expanding knowledge about fluid physics on the other. A prominent example of these advances can be found in the research of two-phase flow with liquid droplets and jets, where high performance computation and sophisticated algorithms for phase tracking enable well resolved and physically accurate simulations of liquid dynamics. Yet, the field of two-phase flow has remained largely unexplored in visualization research so far, leaving the scientists and engineers with a number of challenges when analyzing the data. These include the difficulty in tracking and investigating topological events in large droplet groups, high complexity of droplet dynamics due to the involved interfaces, and a limited choice of high quality interactive methods for the analysis of related transport phenomena. It is therefore the aim of this thesis to address these challenges by providing a multi-scale approach for the visual investigation of two-phase flow, with the focus on the analysis of droplet interaction, fluid interfaces, and material transport. To address the problem of analyzing highly complex two-phase flow simulations with droplet groups and jets, a linked-view approach with three-dimensional and abstract space-time graph representation of droplet dynamics is proposed. The interactive brushing and linking allows for general exploration of topological events as well as detailed inspection of dynamics in terms of oscillations and rotations of droplets. Another approach further examines the separation of liquid phases by segmenting liquid volumes according to their topological changes in future time. For visualization, boundary surfaces of these volume segments are extracted that reveal intricate details of droplet topology dynamics. Additionally, within this framework, visualization of advected particles corresponding to arbitrarily selected segment provides useful insights into the spatio-temporal evolution of the segment. The analysis of interfaces is necessary to understand the interplay of interface dynamics and the dynamics of droplet interactions. A commonly used technique for interface tracking in the volume of fluid-based simulations is the piecewise linear approximation which, although accurate, can affect the quality of the simulation results. To study the influence of the interface reconstruction on the phase tracking procedure, a visualization method is presented that extracts the interfaces by means of the first-order Taylor approximation, and provides several derived quantities that help assess the simulation results in relation to the interface reconstruction quality. The liquid interface is further investigated from the physical standpoint with an approach based on quantities derived from velocity and surface tension gradients. The developed method supports examination of surface tension forces and their impact on the interface instability, as well as detailed analysis of interface deformation characteristics. A line of research important for engineering applications is the analysis of electric fields on droplet interfaces. It is, however, complicated by higher-order elements used in the simulations to preserve field discontinuities. A visualization method has been developed that correctly visualizes these discontinuities at material boundaries. Additionally, the employed space-time representation of the droplet-insulator contact line reveals characteristics of electric field dynamics. The dynamics of droplets are often examined assuming single-phase flow, for instance when the internal material transport is of interest. From the visualization perspective, this allows for adaption of traditional vector field visualization techniques to the investigation of the studied phenomena. As one such concept, dye based visualization is proposed that extends the transport analysis to advection-diffusion problems, therefore revealing true transport behavior. The employed high quality advection preserves fine details of the dye, while the implementation on graphics processing units ensures interactive visualization. Several streamline-based concepts are applied in space-time representation of 2D unsteady flow. By interpreting time as the third spatial dimension, many 3D streamline-based visualization techniques can be applied to investigate 2D unsteady flow. The introduced vortex core ribbons support the examination of vortical flow behavior by revealing rotation near the core lines. For the study of topological structures, a method has been developed that extracts separatrices implicitly as boundaries of regions with different flow behavior, and therefore avoids potentially complicated explicit extraction of various topological structures. All proposed techniques constitute a novel multi-scale approach for visual analysis of two-phase flow. The analysis of droplet interactions is addressed with visualization of the phenomena leading to breakups and with detailed visual inspection of these breakups. On the interface level, techniques for the interface analysis give insights into the simulation quality, mechanisms behind topology changes, as well as the behavior of electrically charged droplets. Further down the scale, the dye-based visualization, streamline-based concepts for space-time analysis, and the implicit extraction of flow topology allow for the investigation of droplet internal transport as well as general single-phase flow scenarios. The applicability of the proposed methods extends, in a varying degree, beyond the use in two-phase flow. Their usability is demonstrated on data from simulations based on Navier-Stokes equations that exemplify practical problems in the research of fluid dynamics. Note de contenu : Introduction
1 - Fundamentals and State of the Art
2 - Visualization of Interactions in Droplet Groups
3 - Visualization of Liquid Interface Dynamics
4 - Visualization Approaches for Material Transport
ConclusionNuméro de notice : 21572 Affiliation des auteurs : non IGN Nature : Thèse étrangère Note de thèse : Doktor thesis : Sciences naturelles : Stuttgart : 2017 En ligne : https://elib.uni-stuttgart.de/handle/11682/9701 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90563
Titre : Brownian motion, martingales, and stochastic calculus Type de document : Guide/Manuel Auteurs : Jean-François Le Gall, Auteur Editeur : Springer International Publishing Année de publication : 2016 Importance : 273 p. Format : 16 x 24 cm ISBN/ISSN/EAN : 978-3-319-31089-3 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Mathématique
[Termes IGN] chaîne de Markov
[Termes IGN] fonction harmonique
[Termes IGN] mouvement brownien
[Termes IGN] probabilités
[Termes IGN] stochastiqueRésumé : (éditeur) This book offers a rigorous and self-contained presentation of stochastic integration and stochastic calculus within the general framework of continuous semimartingales. The main tools of stochastic calculus, including Itô's formula, the optional stepping theorem and Girsanov's theorem, are treated in detail alongside many illustrative examples. The book also contains an introduction to Markov processes, with applications to solutions of stochastic differential equations and to connections between Brownian motion and partial differential equations. The theory of local times of semimartingales is discussed in the last chapter. Since its invention by Itô, stochastic calculus has proven to be one of the most important techniques of modern probability theory, and has been used in the most recent theoretical advances as well as in applications to other fields such as mathematical finance. Brownian Motion, Martingales, and Stochastic Calculus provides a strong theoretical background to the reader interested in such developments. Beginning graduate or advanced undergraduate students will benefit from this detailed approach to an essential area of probability theory. The emphasis is on concise and efficient presentation, without any concession to mathematical rigor. The material has been taught by the author for several years in graduate courses at two of the most prestigious French universities. The fact that proofs are given with full details makes the book particularly suitable for self-study. The numerous exercises help the reader to get acquainted with the tools of stochastic calculus. Numéro de notice : 26586 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Manuel En ligne : https://doi.org/10.1007/978-3-319-31089-3 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95220 Using virtual reality and percolation theory to visualize fluid flow in porous media / Carlos Magno De Lima in Geoinformatica, vol 17 n° 4 (October 2013)
[article]
Titre : Using virtual reality and percolation theory to visualize fluid flow in porous media Type de document : Article/Communication Auteurs : Carlos Magno De Lima, Auteur ; Luis M. G. Gonçalves, Auteur ; Cristiana Bentes, Auteur ; Ricardo Farias, Auteur Année de publication : 2013 Article en page(s) : pp 521 - 541 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique
[Termes IGN] analyse visuelle
[Termes IGN] données localisées 3D
[Termes IGN] dynamique des fluides
[Termes IGN] flux de données
[Termes IGN] modèle de simulation
[Termes IGN] prospection pétrolière
[Termes IGN] réalité virtuelle
[Termes IGN] visualisation 3DRésumé : (Auteur) The study of the fluid flow process through porous media can bring valuable contributions in areas like oil exploration and environmental research. In this work, we propose an interactive tool, named VRFluid, that allows visual interpretation of the three-dimensional data generated by the simulation of the fluid flow the porous media. VRFluid comprises a virtual reality engine that provides stereo visualization of the three-dimensional data, and a simulation engine based on a dynamic percolation method to model the fluid flow. VRFluid is composed of two independent main threads, the percolation simulator and the rendering server, that can operate in parallel as a pipeline. We tested our tool on a region of a mature field database, supervised by geophysicists, and obtained images of the interior of the percolation data, providing important results for the interpretation and cluster formation process. Numéro de notice : A2013-508 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1007/s10707-012-0168-5 Date de publication en ligne : 23/10/2012 En ligne : https://doi.org/10.1007/s10707-012-0168-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32646
in Geoinformatica > vol 17 n° 4 (October 2013) . - pp 521 - 541[article]Réservation
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Titre : Computational Physics Type de document : Guide/Manuel Auteurs : Philipp Scherer, Auteur Editeur : Springer International Publishing Année de publication : 2013 Importance : 454 p. Format : 16 x 24 cm ISBN/ISSN/EAN : 978-3-319-00401-3 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Physique
[Termes IGN] collocation
[Termes IGN] dynamique des fluides
[Termes IGN] équation linéaire
[Termes IGN] interpolation
[Termes IGN] Java (langage de programmation)
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] problème du voyageur de commerce
[Termes IGN] quantum (physique)
[Termes IGN] thermodynamique
[Termes IGN] transformation de Fourier
[Termes IGN] trigonométrieRésumé : (éditeur) This textbook presents basic and advanced computational physics in a very didactic style. It contains very-well-presented and simple mathematical descriptions of many of the most important algorithms used in computational physics. The first part of the book discusses the basic numerical methods. The second part concentrates on simulation of classical and quantum systems. Several classes of integration methods are discussed including not only the standard Euler and Runge Kutta method but also multi-step methods and the class of Verlet methods, which is introduced by studying the motion in Liouville space. A general chapter on the numerical treatment of differential equations provides methods of finite differences, finite volumes, finite elements and boundary elements together with spectral methods and weighted residual based methods. The book gives simple but non trivial examples from a broad range of physical topics trying to give the reader insight into not only the numerical treatment but also simulated problems. Different methods are compared with regard to their stability and efficiency. The exercises in the book are realised as computer experiments. Note de contenu : I- Numerical Methods
II- Simulation of Classical and Quantum SystemsNuméro de notice : 25827 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Manuel En ligne : https://doi.org/10.1007/978-3-319-00401-3 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95121
Titre : Zenith delay correction with GPT2w : improvement of a "blind" tropospheric correction model Type de document : Mémoire Auteurs : Grégory Pain, Auteur Editeur : Champs-sur-Marne : Ecole nationale des sciences géographiques ENSG Année de publication : 2013 Importance : 64 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] correction troposphérique
[Termes IGN] hydrostatique
[Termes IGN] modèle atmosphérique
[Termes IGN] propagation troposphérique
[Termes IGN] retard troposphérique
[Termes IGN] température en altitude
[Termes IGN] teneur en vapeur d'eauIndex. décimale : PROJET Mémoires : Rapports de projet - stage des ingénieurs de 2e année Résumé : (Auteur) Une des erreurs les plus importantes dans les observations en géodésie spatiale comme les systèmes globaux de positionnement par satellites(GNSS)est la modélisation de la traversée de l'atmosphère. C'est pourquoi, la détermination des délais troposphériques est particulièrement importante. Ces délais peuvent être séparés en deux parties indépendantes: une partie humide, l'autre dite hydrostatique (Saastamoinen, 1973).Partant d'un modèle empirique “aveugle” appelé GPT2 capable de déterminer la partie hydrostatique de ces délais (Lagler et al., 2013), un nouveau modèlenomméGPT2w fut développé lors de ce stage et est présenté dans ce rapport. Basé sur des données météorologiques du modèle numérique ERA-Interim du Centre Européen de Prévision Météorologique à Moyen Terme (CEPMMT, ECMWF en anglais), deux nouveaux paramètres un facteur de décroissance de la vapeur d'eau et une température moyenne ont été introduits pour pouvoir calculer la partie humide comme suggéré par (Askne and Nordius, 1987)et sont donc maintenant délivrés par GPT2w. Après avoir déterminé la résolution nécessaire pour ces paramètres (1° x 1° contre 5° x 5° pour GPT2), une comparaison avec des délais troposphériques dérivés de mesures GPS a été réalisée pour 167stations IGS de référence sur la période 2011-2012. GPT2w présente ainsi un biais moyen de -0.1 mm et une RMS de 39.9 mm. Note de contenu : INTRODUCTION
1 TECHNICAL BACKGROUNDS
1.1 Definition of zenith delays
1.1.1 Zenith hydrostatic delays
1.1.2 Zenith wet delays
1.1.3 Ray tracing
1.2 Objectives & Context
1.2.1 GPT2
1.2.2 Definition of the new parameters
1.2.3 Presentation of the used data
1.3 Data processing
1.3.1 Harmonic decomposition
1.3.2 Validation Phase
2 INTRODUCTION OF NEW PARAMETERS
2.1 Water vapor decrease factor
2.1.1 Choice of the grid
2.1.2 Results
2.2 Mean temperature of the water vapor
2.2.1 Choice of the grid
2.2.2 Results
2.3 Internal validation
2.3.1 "No Height" problem
2.3.2 "Wrong Height" problem
2.3.3 Final results
3 EXTERNAL VALIDATION
3.1 Comparison of ZTD for the 2012 year
3.1.1 Data processing
3.1.2 Results
3.2 Modification of the water vapor partial pressure determination
3.2.1 Data processing
3.2.2 Validation of the changes
3.3 Final comparisons of ZTD for the 2011-2012 Period
3.3.1 ZTD comparison for the 2011-2012 Period
3.3.2 Comparison with TropGrid2
CONCLUSIONNuméro de notice : 11984 Affiliation des auteurs : IGN (2012-2019) Thématique : POSITIONNEMENT Nature : Mémoire de projet pluridisciplinaire Organisme de stage : Vienna University of Technology Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=49815 Réservation
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