Download or read book Structure de jets l gers ou lourds en coulement externe fortement puls written by Yannick Bury and published by . This book was released on 2000 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cette thèse s'inscrit dans le cadre de l'étude des écoulements turbulents fortement instationnaires avec larges variations de densité. Elle s'insère dans une action globale de compréhension des mécanismes physiques régissant le mélange air/carburant dans les moteurs à piston du secteur automobile, notamment de carburants gazeux tels que le GNV. La dynamique et le mélange dans un jet à densité variable en écoulement cocourant fortement pulsé sont étudiés. Cette configuration modélise la situation moteur. Une importante base de données sur des jets léger, homogène et lourd est obtenue pour des vitesses de cocourant stationnaire et instationnaire contrastées. Les champs de vitesse sont mesurés par anémométrie Laser Doppler bicomposantes, les champs de fraction massique et de densité moyenne par tomographie laser. Les mesures et l'analyse physique permettent de comprendre ces écoulements. Une partition du jet en régions quasi statique et instationnaire est proposée. Les effets de mémoire observés dans la zone instationnaire peuvent être appréhendés par un modèle hyperbolique. Un front de vitesse de type jet naissant se développe lors de l'accélération et se traduit par un effet important sur le champ turbulent. L'étude phasée de la topologie du jet montre que ce front s'assimile à une boule de fluide concentrée, analogue au vortex des jets naissants ou aux jets pulsés. Le mélange avec le fluide extérieur est réduit à son passage et plus généralement pendant toute l'accélération. Au contraire il semble légèrement accru pendant la décélération. Le rôle des couples baroclines sur le champ moyen et la turbulence est identifié. Des nombres sans dimension sont mis en évidence pour traduire ce régime de convection mixte instationnaire. La confrontation de ces résultats avec des simulations numériques en éprouvera la validité en situation fortement instationnaire.
Download or read book Analyse de la dynamique des jets densit variable en coulement cocourant puls written by Marc Saudreau and published by . This book was released on 2002 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cette thèse s'inscrit dans le cadre de l'étude des écoulements turbulents fortement instationnaires avec larges variations de densité. Elle s'insère dans une action globale de compréhension des mécanismes physiques régissant le mélange air / carburant gazeux (GNV) dans les moteurs à piston. L'objectif de cette étude est d'analyser la dynamique des jets à densité variable en écoulement cocourant fortement pulsé. L'analyse a été conduite en se basant à la fois sur des données expérimentales obtenues par ánémométrie Laser Doppler bicomposantes, et une approche numérique par résolution des équations de Navier-Stokes moyennées (RANS). Outre le test de la pertinence des modèles de fermeture (k - e, Rij-e), cettes complémentarité permet d'apprécier l'impact de l'instationnarité sur le développement moyen et turbulent du jet. L'instationnarité modifie le flux d'excès de quantité de mouvement initial et impose à l'écoulement un champ d'accélération variable en temps. La réponse du jet à ces deux sollicitations dépend de sa capacité à s'adapter aux changements des conditions d'initial. Cette capacité liée au transport advectif induit une partition du jet en régions quasi statique et instationnaire. Les effets de mémoire observés dans la zone instationnaire peuvent être appréhendés par un modèle hyperbolique. Un front de vitesse de type jet naissant se développe lors de l'accélération et se traduit par un effet important sur le champ turbulent. Le mélange avec le fluide extérieur est réduit à son passage et plus généralement pendant toute l'accélération. En phase de décélération le gradient de pression contrôle la dynamique de l'écoulement. Dans le cas du jet à densité variable, le couplage avec le gradient de densité induit une force de flottabilité. En situation de jet léger, la structure moyenne de l'écoulement passe alors d'un jet à un sillage. Les conséquences sur la turbulence et le mélange sont identifiées et expliquées.
Download or read book Genmix written by D Brian Spalding and published by Elsevier. This book was released on 2014-05-18 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt: Genmix: A General Computer Program for Two-dimensional Parabolic Phenomena explains a computer program called GENMIX. The main intention of the program is to be used as a tool of instructions. The name of the program is a mixture of two considerations: its generality and its concern for mixing processes. The book aims to help the potential user to understand the physical and mathematical basis of the topic computer program. It is also the aim of the book to make the program applicable to practical problems. The book is arranged in such a way as to parallel a course of lectures and associated computer-workshop sessions wherein the student is allowed to do some elementary computations as soon as he has gained some knowledge of the method. The book contains the mathematical, physical, and computer-coding aspects of the program. Concepts such as the boundary layer, two-dimensional, and steady- flow are defined and discussed in depth. The text will be a useful tool for computer instructors and students.
Download or read book Agroclimatology written by Jerry L. Hatfield and published by John Wiley & Sons. This book was released on 2020-01-22 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: Can we unlock resilience to climate stress by better understanding linkages between the environment and biological systems? Agroclimatology allows us to explore how different processes determine plant response to climate and how climate drives the distribution of crops and their productivity. Editors Jerry L. Hatfield, Mannava V.K. Sivakumar, and John H. Prueger have taken a comprehensive view of agroclimatology to assist and challenge researchers in this important area of study. Major themes include: principles of energy exchange and climatology, understanding climate change and agriculture, linkages of specific biological systems to climatology, the context of pests and diseases, methods of agroclimatology, and the application of agroclimatic principles to problem-solving in agriculture.
Download or read book Faecal Sludge Management written by Linda Strande and published by IWA Publishing. This book was released on 2014-08-15 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is estimated that literally billions of residents in urban and peri-urban areas of Africa, Asia, and Latin America are served by onsite sanitation systems (e.g. various types of latrines and septic tanks). Until recently, the management of faecal sludge from these onsite systems has been grossly neglected, partially as a result of them being considered temporary solutions until sewer-based systems could be implemented. However, the perception of onsite or decentralized sanitation technologies for urban areas is gradually changing, and is increasingly being considered as long-term, sustainable options in urban areas, especially in low- and middle-income countries that lack sewer infrastructures. This is the first book dedicated to faecal sludge management. It compiles the current state of knowledge of the rapidly evolving field of faecal sludge management, and presents an integrated approach that includes technology, management, and planning based on Sandecs 20 years of experience in the field. Faecal Sludge Management: Systems Approach for Implementation and Operation addresses the organization of the entire faecal sludge management service chain, from the collection and transport of sludge, and the current state of knowledge of treatment options, to the final end use or disposal of treated sludge. The book also presents important factors to consider when evaluating and upscaling new treatment technology options. The book is designed for undergraduate and graduate students, and engineers and practitioners in the field who have some basic knowledge of environmental and/or wastewater engineering.
Download or read book UNESCO General History of Africa Vol I Abridged Edition written by Jacqueline Ki-Zerbo and published by Univ of California Press. This book was released on 1990 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This volume covers the period from the end of the Neolithic era to the beginning of the seventh century of our era. This lengthy period includes the civilization of Ancient Egypt, the history of Nubia, Ethiopia, North Africa and the Sahara, as well as of the other regions of the continent and its islands."--Publisher's description
Download or read book Basic Technics in Ecological Farming Techniques de Base en Agriculture Biologique Grunds tzliche Verfahren der kologischen Landwirtschaft Le Maintien de la Fertilit des Sols The Maintenance of Soil Fertility Die Erhaltung der Bodenfruchtbarkeit written by Stuart Hill and published by Birkhäuser. This book was released on 2013-12-14 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dictionary of the French and English Languages written by Gabriel Surenne and published by . This book was released on 1856 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heat and Mass Transfer in Boundary Layers written by Suhas V. Patankar and published by . This book was released on 1970 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wind tunnel Investigation of a Number of Total pressure Tubes at High Angles of Attack written by A. Gerald Rainey and published by . This book was released on 1957 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CASTI Metals Black Book written by John E. Bringas and published by . This book was released on 2003 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Metals Black Book written by Michael Lash Wayman and published by . This book was released on 1998 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Parallel Finite Volume Algorithm for Large eddy Simulation of Turbulent Flows written by Trong T. Bui and published by . This book was released on 1998 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Differential Manifolds written by Jacques Lafontaine and published by Springer. This book was released on 2015-07-29 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an introduction to differential manifolds. It gives solid preliminaries for more advanced topics: Riemannian manifolds, differential topology, Lie theory. It presupposes little background: the reader is only expected to master basic differential calculus, and a little point-set topology. The book covers the main topics of differential geometry: manifolds, tangent space, vector fields, differential forms, Lie groups, and a few more sophisticated topics such as de Rham cohomology, degree theory and the Gauss-Bonnet theorem for surfaces. Its ambition is to give solid foundations. In particular, the introduction of “abstract” notions such as manifolds or differential forms is motivated via questions and examples from mathematics or theoretical physics. More than 150 exercises, some of them easy and classical, some others more sophisticated, will help the beginner as well as the more expert reader. Solutions are provided for most of them. The book should be of interest to various readers: undergraduate and graduate students for a first contact to differential manifolds, mathematicians from other fields and physicists who wish to acquire some feeling about this beautiful theory. The original French text Introduction aux variétés différentielles has been a best-seller in its category in France for many years. Jacques Lafontaine was successively assistant Professor at Paris Diderot University and Professor at the University of Montpellier, where he is presently emeritus. His main research interests are Riemannian and pseudo-Riemannian geometry, including some aspects of mathematical relativity. Besides his personal research articles, he was involved in several textbooks and research monographs.
Download or read book Aeronomy written by P. M. Banks and published by Elsevier. This book was released on 2013-09-24 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aeronomy, Part A is an attempt to make a comprehensive exposition of the processes in aeronomy, the study of composition, movement, and thermal balance of the upper regions of the planetary atmosphere. The text covers topics such as atmospheric regions and atmospheric density, the temperature and molecular mass of the atmosphere; the permanent constituents and the molecular and isotonic composition of the homosphere; and the transition from the homosphere to the heterosphere. Also covered are topics such as the temperature gradient and energies in the thermosphere, conditions at 200km and above 250km, solar radiation and ionization, and aeronomic reactions. The book is recommended for scientists, especially natural physicists, who would like to know more about the field of aeronomy and its advances.
Download or read book Chemistry of Lignocellulosics written by Taylor & Francis Group and published by CRC Press. This book was released on 2021-03-31 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the chemical properties of lignocellulosic fibers, knowledge of which is essential for innovation and sustainable development of their transformation. Thermochemical transformation of wood and other lignocellulosics is presented to highlight its volatile, liquid and solid products and their novel applications. Forest biorefinery is described to emphasize the new products from lignocellulosic constituents, both structural (cellulose, hemicelluloses and lignins) and those extraneous to cell walls-extractives. New developments in cellulose technology related to nanocellulose are discussed in relation to new applications. Industrial lignins are presented in detail, both in terms of extraction procedures from spent liquors and structural characterization of the isolated lignins. Application of lignocellulosic biopolymers in new composite materials, or in biomaterials for medicinal purposes, and in solid wood preservation, are described. The example of an industrial biorefinery installed in southwestern France more than 40 years ago is presented.
Download or read book Convective Mass Transfer written by Dudley Brian Spalding and published by . This book was released on 1963 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
