CE TRAVAIL PORTE SUR LA MODELISATION NUMERIQUE DES FLAMMES DE DIFFUSION TURBULENTES INSTATIONNAIRES, CARACTERISTIQUES DES FEUX DE VEGETATION. LE BUT EST DE MIEUX COMPRENDRE LES DIFFERENTS MECANISMES RESPONSABLES DE LA PROPAGATION. LE MODELE BIDIMENSIONNEL MULTIPHASIQUE PROPOSE TIENT COMPTE DES PRINCIPAUX PHENOMENES QUI REGISSENT L'ECLOSION ET LA PROPAGATION DU FEU. IL CONTIENT DES SOUS MODELES DE TURBULENCE (RNG ) ET DE COMBUSTION TURBULENTE (MODELE EDDY DISSIPATION CONCEPT). LA METHODE DES ORDONNEES DISCRETES, ETENDUE AUX MILIEUX MULTIPHASIQUES EST UTILISEE POUR LE RAYONNEMENT. LE GAZ CONSIDERE EST NON TRANSPARENT, ET SES PROPRIETES TIENNENT COMPTE DE LA FORMATION DES SUIES. LE SOUS MODELE DE DEGRADATION THERMIQUE COMPRENDS LA DESHYDRATATION, LA PYROLYSE ET LA COMBUSTION DES RESIDUS CHARBONNEUX DU COMBUSTIBLE HETEROGENE. NOUS AVONS MIS EN UVRE UNE METHODE NUMERIQUE DE TYPE VOLUMES FINIS QUI UTILISE UN ALGORITHME DIRECT DERIVE DE LA METHODE DES PROJECTIONS DE CHORIN. NOUS POUVONS AINSI PREDIRE LE DEVELOPPEMENT DU FEU DE LA PHASE D'INITIATION A LA PHASE DE PROPAGATION QUASI-STATIONNAIRE, ET LA COMPARAISON AVEC DES RESULTATS EXPERIMENTAUX EST ENCOURAGEANTE. LE MODELE DEVELOPPE EST ENSUITE APPLIQUE A LA DESCRIPTION DU COMPORTEMENT D'UN FEU SE PROPAGEANT A TRAVERS UNE VEGETATION COMPORTANT DES DISCONTINUITES HORIZONTALES DANS LA DISTRIBUTION DU COMBUSTIBLE (COUPURES ANTI-FEU), ET UNE ETUDE PARAMETRIQUE EST MENEE DE MANIERE A DETERMINER LES PARAMETRES SENSIBLES DU MODELE. ON OBSERVE FINALEMENT LE ROLE DETERMINANT JOUE PAR LE RAYONNEMENT DANS L'EVALUATION DE L'EFFICACITE D'UNE COUPURE POUR DES CONDITIONS DE PENTE ET DE VENT VARIEES.

LA PROPAGATION D'UN INCENDIE DE VEGETATION EST LA REALITE QUE NOUS AVONS SOUHAITE PREDIRE. L'OBJECTIF A LONG TERME QUE NOUS NOUS SOMMES FIXE EST DE FOURNIR UN OUTIL DE PREDICTION DE LA PROPAGATION D'UN FEU DE VEGETATION BASE SUR LE PRINCIPE DE CONSERVATION DE L'ENERGIE. POUR REPONDRE AUX CRITERES DE RAPIDITE DE CALCUL QU'UN TEL OUTIL NECESSITE, ET ETANT DONNE LE GRAND NOMBRE DE FACTEURS QUI INFLUENCENT DE FACON SIGNIFICATIVE LA PROPAGATION DU FEU, NOUS NOUS SOMMES ORIENTES VERS UNE REPRESENTATION GLOBALE DU PHENOMENE. LES MECANISMES DE PRODUCTION ET DE TRANSFERT DE CHALEUR SONT ALORS MODELISES D'UNE FACON SIMPLE ET CERTAINS PROCESSUS ELEMENTAIRES SONT GLOBALISES AU MOYEN D'UN SEUL TERME DANS LE BILAN D'ENERGIE. AINSI, LES COEFFICIENTS QUI CARACTERISENT CES MECANISMES NE SONT ACCESSIBLES QU'A PARTIR DE MESURES EXPERIMENTALES. NOTRE APPROCHE EST DONC UNE DEMARCHE INTERMEDIAIRE SITUEE ENTRE LES FORMULATIONS EMPIRIQUE ET PHYSIQUE, QUE NOUS POUVONS QUALIFIER DE SEMI-PHYSIQUE. LES PREDICTIONS DU MODELE ONT ETE CONFRONTEES A PLUSIEURS SERIES D'EXPERIENCES CONDUITES SUR DES LITIERES D'AIGUILLES DE PIN. SUR LA BASE DES CONCLUSIONS DE L'ETUDE PRELIMINAIRE, LA MODELISATION DU TERME DE RAYONNEMENT DES FLAMMES DANS LE BILAN D'ENERGIE A ETE AMELIOREE. LE FRONT DE FLAMME EST ALORS ASSIMILE A UN PANNEAU RADIANT. LA FRACTION D'ENERGIE RAYONNEE PAR UNE SURFACE ELEMENTAIRE DE LA FLAMME, QUI EST INTERCEPTEE PAR LE COMBUSTIBLE IMBRULE SITUE DEVANT LE FRONT, EST CALCULEE PAR UN FACTEUR DE FORME. LE RAYONNEMENT DES FLAMMES EST SUPPOSE ETRE LE MODE DE TRANSFERT DE CHALEUR DOMINANT EN PRESENCE D'UNE PENTE ET/OU DE VENT ET LES MECANISMES CONVECTIFS SONT NEGLIGES. LE MODELE AMELIORE A PERMIS DE RENDRE COMPTE DE MANIERE SATISFAISANTE DES PRINCIPALES CARACTERISTIQUES DE LA PROPAGATION D'UN FEU A L'ECHELLE D'UNE LITIERE D'AIGUILLES DE PIN. LES PREDICTIONS DU MODELE PERMETTENT AUSSI D'IDENTIFIER LES CAS DANS LESQUELS L'INFLUENCE DU RAYONNEMENT EST SIGNIFICATIVE.

Grassfirespresents the latest information from CSIRO on the behavior and spread of fires in grasslands. This second edition follows ten years of research aimed at improving the understanding of fundamental processes involved in the behavior of bushfires and grassfires. The book has been extensively revised and new case studies have been added to reflect the latest findings in research and investigations. The book covers all aspects of fire behavior and spread in the major types of grasses in Australia. It examines the factors that affect fire behavior in continuous grassy fuels; fire in spinifex fuels; the effect of weather and topography on fire spread; wildfire suppression strategies; and how to reconstruct grassfire spread after the fact. The three fire-spread meters designed by CSIRO and used for the prediction of fire danger and rate of spread of grassfires are explained and their use and limitations discussed. This new edition expands on the historical view of grassfires with respect to extensive Aboriginal burning, combustion chemistry, flame structure and temperature, spotting and spread in discontinuous/eaten out fuels, and the effect of wind in complex terrain. The case studies in the chapter "Wildfires and Their Suppression" have been updated and include the major wild grassfire events of recent years, the January 2003 ACT fires and the 2005 Wangary, SA fire. The "Myths, Facts and Fallacies" chapter includes new myths and a new section on personal safety during a wild grass fire. Of interest to all rural fire fighters and rural landholders, students and teachers of courses on landscape and ecological processes, rural and peri-urban dwellers, fire authorities and researchers.

This Open Access book explains that after long periods of prehistoric research in which the importance of the archaeological as well as the natural context of rock art has been constantly underestimated, research has now begun to take this context into focus for documentation, analysis, interpretation and understanding. Human footprints are prominent among the long-time under-researched features of the context in caves with rock art. In order to compensate for this neglect an innovative research program has been established several years ago that focuses on the merging of indigenous knowledge and western archaeological science for the benefit of both sides. The book gathers first the methodological diversity in the analysis of human tracks. Here major representatives of anthropological, statistical and traditional approaches feature the multi-layered methods available for the analysis of human tracks. Second it compiles case studies from around the globe of prehistoric human tracks. For the first time, the most important sites which have been found worldwide are published in a single publication. The third focus of this book is on firsthand experiences of researchers with indigenous tracking experts from around the globe, expounding on how archaeological sciencecan benefit from the ancestral knowledge. This book will be of interest to professional archaeologists, graduate students, ecologists, cultural anthropologists and laypeople, especially those focussing on hunting-gathering and pastoralist communities and who appreciate indigenous knowledge.--

Explaining the science contained in a simple assembly of grains—the most abundant form of matter present on Earth. Granular media—composed of vast amounts of grains, consolidated or not—constitute the most abundant form of solid matter on Earth. Granular materials assemble in disordered configurations scientists often liken to a bag of marbles. Made of macroscopic particles rather than molecules, they defy the standard scheme of classification in terms of solid, liquid, and gas. Granular materials provide a model relevant to various domains of research, including engineering, physics, and biology. William Blake famously wished “To See a World in a Grain of Sand”; in this book, pioneering researchers in granular matter explain the science hidden behind simple grains, shedding light on collective behavior in disordered settings in general. The authors begin by describing the single grain with its different origins, shapes, and sizes, then examine grains in piled or stacked form. They explain the packing fraction of granular media, a crucial issue that bears on the properties displayed in practical applications; explore small-scale deformations in piles of disordered grains, with particular attention to friction; and present theories of various modes of disorder. Along the way, they discuss such concepts as force chains, arching effects, wet grains, sticky contacts, and inertial effects. Drawing on recent numerical simulations as well as classical concepts developed in physics and mechanics, the book offers an accessible introduction to a rapidly developing field.

The world’s ever-increasing need for fresh water has led to the use of non-conventional sources such as rain and fog water collection. Although rain water collection is relatively simple, the supply is often erratic. Passive fog water collection has been used in several parts of the world but is only relevant to certain geographical locations. Dew occurrence, however, is far more widespread, can form in most climates and geographic settings, show high frequency and prevalence throughout the year. During the past 20 years, dew collection has therefore been investigated as a serious supplemental source of fresh water. Dew Water offers a thorough review of dew, its formation characteristics and potential for dew collection, for audiences that include policy-makers, non-governmental organizations involved in development aid and sustainable development, engineers, urban planners, researchers and students.After providing a background on atmospheric water, humid air, and sky and materials emissivity, the book deals with dew formation and its estimation with a focus on the use of meteorological data. Dew measurement techniques are reviewed and discussed as well as dew collection by passive means. Computational fluid dynamics technique is described for better design of dew collectors. Dew quality (chemistry, biology) is assessed in view of potable water quality. Costs and economic aspects are also considered.