Download or read book Introduction d une partition ondes turbulence dans les mod les de transport pour les coulements turbulents stablement stratifi s written by Fabien Godeferd and published by . This book was released on 1994 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Le travail presenté traite de la turbulence incompressible homogène en présence d'une stratification stable. L'approche de celle-ci s'effectue principalement au moyen d'un modèle statistique en deux points, de type Eddy Damped Quasi Normal Markovian (EDQNM), qui est presenté de manière globale. Ce modèle, en configuration axisymétrique, utilise une décomposition du champ de vitesse fluctuante sur la base des modes propres des équations de boussinesq linéarisées: ondes internes irrotationnelles et mode stationnaire à rotationnel horizontal (mode vortex). Les différents termes d'interactions non linéaires entre modes ondes et vortex dans le transfert pour le spectre des corrélations doubles sont etudiées en détail, de même que la contribution des interactions résonantes à la dynamique non linéaire. L'influence de la stratification sur la turbulence est caractérisée à la fois dans l'espace spectral par une anisotropie de directivité et de polarisation des spectres, et dans l'espace physique au moyen d'échelles intégrales suivant les directions verticale et horizontale. Une simulation cinématique utilisant les propriétés statistiques calculées permet d'appréhender la structuration en couches décorrélées de la turbulence. De plus, grace aux propriétés des ondes de gravité, des liens sont établis avec les écoulements géophysiques dans une approximation géostrophique, ainsi qu'avec des approches d'interactions triadiques non linéaires. Une étude analytique d'interactions purement linéaires entre ondes permet d'etudier la diffusion de l'énergie d'un spectre isotrope par les ondes internes, dans une configuration faiblement non homogène. Finalement, est effectuée une comparaison des quantités en un point calculées au moyen de l'EDQNM, avec le modèle statistique en un point de Craft & Launder pour une turbulence stratifiée, au travers des termes linéaires et non linéaires des corrélations de pression-vitesse et de pression-température

Download or read book MODELISATION DE LA TURBULENCE EN ECOULEMENTS STRATIFIES POUR L ATMOSPHERE URBAINE written by BRUNO.. ABART and published by . This book was released on 1999 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE THESE CONCERNE LA MODELISATION STATISTIQUE DE LA TURBULENCE SOUMISE A UNE STRATIFICATION THERMIQUE. S'INSCRIVANT DANS LA PERSPECTIVE D'APPLICATIONS A LA SIMULATION NUMERIQUE D'ECOULEMENTS A L'ECHELLE URBAINE, CE TRAVAIL PORTE ESSENTIELLEMENT SUR LA MODELISATION STATISTIQUE AU PREMIER ORDRE. AFIN DE MINIMISER LES EFFETS DE DIFFUSION NUMERIQUE, UNE METHODE DE DISCRETISATION DIRECTE DES OPERATEURS, PRECISE AU SECOND ORDRE SUR MAILLAGE CURVILIGNE, EST CONSTRUITE ET VALIDEE. L'ANALYSE DES EQUATIONS STATISTIQUES DU TENSEUR DE REYNOLDS, DU FLUX DE CHALEUR ET DE LA VARIANCE DE TEMPERATURE, PT2, EN STRATIFICATION STABLE CONDUIT A UNE REPRESENTATION CONCEPTUELLE DE L'ANISOTROPISATION DE LA TURBULENCE ET DES ECHANGES ENTRE L'ENERGIE CINETIQUE TURBULENTE, TKE, ET L'ENERGIE POTENTIELLE. A L'AIDE DE CETTE REPRESENTATION, RESUMEE PAR UNE ANALOGIE HYDRAULIQUE, UN MODELE TKE-EPS, OU EPS EST LE TAUX DE DISSIPATION DE TKE, POUR LA STRATIFICATION STABLE ET UN MODELE A CINQ EQUATIONS DE TRANSPORT SONT CONSTRUITS. UNE SECONDE STRATEGIE CONSISTE A EFFECTUER UN DEVELOPPEMENT LIMITE DES CORRELATIONS TURBULENTES AUTOUR DE L'ETAT D'ISOTROPE EN FONCTION DE L'ECHELLE DE TEMPS DE LA TURBULENCE TAU = TKE/EPS. CETTE APPROCHE, APPLIQUEE AUX EQUATIONS DE TRANSPORT D'UN MODELE DE SECOND ORDRE, CONDUIT A UN MODELE NON LINEAIRE ORIGINAL UTILISANT LES EQUATIONS DE TRANSPORT POUR TKE, EPS ET PT2. CE DERNIER MODELE EST EXPLICITE ET QUADRATIQUE EN TAU. CONTRAIREMENT AUX MODELES EXPLICITES USUELS QUI SE LIMITENT AUX TERMES QUADRATIQUES HOMOGENES DE LA DYNAMIQUE, IL PRESENTE EXPLICITEMENT LES COUPLAGES DE LA DYNAMIQUE ET DE LA THERMIQUE, ET LES TERMES D'HETEROGENEITE. CES TROIS MODELES ET LES MODELES CLASSIQUES DE PREMIER ET SECOND ORDRE DE LA LITTERATURE SONT ANALYSES SUR UN ECOULEMENT DE REFERENCE TURBULENT, CISAILLE ET STRATIFIE STABLE ETUDIE PAR KALTENBACH ET AL., 1994. LA SIMULATION DE DEUX ECOULEMENTS ATMOSPHERIQUES, PRESENTANT DE FORTES HETEROGENEITES DANS LA COUCHE DE SURFACE, PERMETTENT UNE PREMIERE QUALIFICATION DE CES MODELES POUR L'ATMOSPHERE URBAINE : _ L'EVOLUTION DIURNE DE LA COUCHE LIMITE DE WANGARA (CLARK ET AL., 1971), _ LE DEVELOPPEMENT DE LA TEMPETE DE BOULDER (LILLY ET ZIPSER, 1972). POUR CES ECOULEMENTS DE REFERENCE, LE MODELE NON LINEAIRE A TROIS EQUATIONS SE REVELE LE PLUS APTE A DECRIRE LE COMPORTEMENT DE LA TURBULENCE SOUMISE A UNE STRATIFICATION THERMIQUE.

Download or read book Le Golfe Du Saint Laurent petit Oc an Ou Grand Estuaire written by Canada. Department of Fisheries and Oceans and published by Peches Et Oceans Direction Generale Des Communications = Fisheries and Oceans Communications Dir. This book was released on 1991 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of a workshop, the scientific reviews and the contributed papers presented at the symposium. The document presents a brief historical summary of marine research in the Gulf; reports the discussions, conclusions and recommendations of the different working groups on oceanography (physics, biology, chemistry and sedimentology) and on the fishery (fish and invertebrates); then presents the discussions of each multidisciplinary working group, centered around how the St. Lawrence system may be used as a natural laboratory which will contribute to the solution of major long-term problems of conservation of natural resources and of the quality of the environment.

Download or read book Instabilities in Multiphase Flows written by A. Berlemont and published by . This book was released on 2014-01-15 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exploring Chaos written by Nina Hall and published by W. W. Norton & Company. This book was released on 1994 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chaos theory is giving scientists fresh insights into all sorts of unruly phenomena-from dripping faucets to swinging pendulums, from the vagaries of the weather to the movements of the planets, from heart rhythms to gold futures. In this collection of front-line reports, edited for the general reader, internationally recognized experts such as Ian Stewart, Robert M. May, and Benoit Mandelbrot draw on the latest research to trace the roots of chaos in modern science and mathematics.

Download or read book Mathematical Theory of Incompressible Nonviscous Fluids written by Carlo Marchioro and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid dynamics is an ancient science incredibly alive today. Modern technol ogy and new needs require a deeper knowledge of the behavior of real fluids, and new discoveries or steps forward pose, quite often, challenging and diffi cult new mathematical {::oblems. In this framework, a special role is played by incompressible nonviscous (sometimes called perfect) flows. This is a mathematical model consisting essentially of an evolution equation (the Euler equation) for the velocity field of fluids. Such an equation, which is nothing other than the Newton laws plus some additional structural hypo theses, was discovered by Euler in 1755, and although it is more than two centuries old, many fundamental questions concerning its solutions are still open. In particular, it is not known whether the solutions, for reasonably general initial conditions, develop singularities in a finite time, and very little is known about the long-term behavior of smooth solutions. These and other basic problems are still open, and this is one of the reasons why the mathe matical theory of perfect flows is far from being completed. Incompressible flows have been attached, by many distinguished mathe maticians, with a large variety of mathematical techniques so that, today, this field constitutes a very rich and stimulating part of applied mathematics.

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer. This book was released on 1976 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis· seminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) *at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac· tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 20 (thesis year 1975) a total of 10,374 theses titles from 28 Canadian and 239 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. The organization of Volume 20 is identical to that of past years. It consists of theses titles arranged by discipline and by university within each discipline.

Download or read book The Problems of the Arid Zone written by Unesco and published by paris. This book was released on 1962 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Census of U S Civil Aircraft written by and published by . This book was released on 1988 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Use of Analog and Digital Computers in Hydrology Proceedings of the Tucson Symposium written by tucson Symposium on the use of analog and digital computers in hydrology and published by . This book was released on 1969 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: