Reliable soot predictions in turbulent flames remain challenging due to the need to use relatively large chemical mechanisms and the presence of slow kinetics of the soot species that necessitate the ...use of an advanced combustion sub-model but prevent tabulation for all species in particular for soot precursor species such as PAHs. The joint probability density function (PDF) approach offers a “model-free” closure for the chemical source term but its computational expense typically hinders the incorporation of detailed soot mechanisms. In this study, a sparse particle method called ‘Multiple Mapping Conditioning’ (MMC) is used. The number of stochastic particles can be reduced by almost two orders of magnitude and large-eddy simulations of a turbulent ethylene flame with a detailed sectional soot model become feasible. Predicted concentrations of gaseous species and temperature agree well with experimental data and indicate an accurate modelling of the turbulent mixing process and gas phase reactions by MMC-LES. MMC-LES with the detailed sectional soot model and a second MMC-LES using a two-equation model provide accurate predictions of the zones where soot is formed and capture the onset of oxidation very well. Simulated peak values of soot volume fraction differ depending on the model, with values being around three times too large for the two-equation model while the detailed sectional model gives very decent agreement everywhere except in the very rich region along the centreline where soot volume fraction are overpredicted by up to 50%. The sectional model yields reasonable results for the aggregate size distributions everywhere in the flame and also the primary particle sizes predicted by the two-equation model agree with expected values, but a quantitative assessment is difficult as corresponding measurements are not available.
Large-eddy-simulation of turbulent non-premixed combustion requires sufficient flame front resolution to predict diffusion flame structures. A novel approach which aims at controlling the filtered ...reactive layer is proposed, irrespective of the local strain rate and mesh size. This approach is developed in the F-TACLES (Filtered tabulated chemistry for LES) framework. To ensure a robust application to diffusion flames, a new gradient-law closure for the mixture fraction is developed and a strategy which adapts the local flame filter size is proposed to control the reactive flame thickness. A posteriori tests are undertaken on 1-D counterflow diffusion flames and the 3-D turbulent coaxial HYLON (Hydrogen Low-NOx) injector developed at IMFT Toulouse. Implementation of the gradient-law closure for the mixture fraction equation proves to be a robust way in conserving scalar transport of the resolved mixture fraction, and it is shown in 1-D counterflow diffusion flames that the total heat release rate is conserved for various filter sizes. The new variable filter size approach outperforms traditional constant filter size cases in predicting the overall flame shape. Since the variable filter uses an optimal filter size, the flame wrinkling is also highest in comparison to constant filter cases where diffusion flames are often over-filtered.
The use of flamelet-type approaches in Large-Eddy-Simulations (LES) remain popular due to their low CPU cost. Of the many flamelet-type approaches, multi-regime flamelet tabulations have emerged as ...an attractive solution for capturing partially-premixed flame structures. Two key challenges associated with multi-regime flamelet tabulation are correctly distinguishing between different combustion regimes and the coupling with the LES, where flame structures are unresolved at the mesh scale. The F-TACLES (Filtered tabulated chemistry for LES) model is formally extended to multi-regime combustion by incorporating the partially-premixed tabulation strategy 2PFT. This new F-TACLES model utilises the tabulation coordinates of filtered mixture fraction, filtered progress variable and the resolved scalar dissipation rate of the mixture fraction. A priori tests are undertaken on 1D flames with varying archetypes and finally a 2D triple flame with varying levels of mixture fraction gradients is tested. The multi-regime F-TACLES approach is validated and is shown to outperform mono-archetype F-TACLES models.
•Wall-resolved and wall-modelled large eddy simulation can capture wake bimodality.•Front separation bubbles shed large hairpin vortices that are convected downstream.•The shedding process is ...associated with high levels of turbulent kinetic energy.•This zone of high turbulent kinetic energy is required for wake bimodal switches.
A large eddy simulation (LES) study of the flow around a 1/4 scale squareback Ahmed body at ReH=33,333 is presented. The study consists of both wall-resolved (WRLES) and wall-modelled (WMLES) simulations, and investigates the bimodal switching of the wake between different horizontal positions. Within a non-dimensional time-window of 1050 convective flow units, both WRLES and WMLES simulations, for which only the near-wall region of the turbulent boundary layer is treated in a Reynolds-averaged sense, are able to capture horizontal (spanwise) shifts in the wake’s cross-stream orientation. Equilibrium wall-models in the form of Spalding’s law and the log-law of the wall are successfully used. Once these wall-models are, however, applied to a very coarse near-wall WMLES mesh, in which a portion of the turbulent boundary layer’s outer region dynamics is treated in a Reynolds-averaged manner as well, large-scale horizontal shifts in the wake’s orientation are no longer detected. This suggests larger-scale flow structures found within the turbulent boundary layer’s outer domain are responsible for generating the critical amount of flow intermittency needed to trigger a bimodal switching event. By looking at mean flow structures, instantaneous flow features and their associated turbulent kinetic energy (TKE) production, it becomes clear that the front separation bubbles just aft of the Ahmed body nose generate high levels of TKE through the shedding of large hairpin vortices. Only in the reference WRLES and (relatively) fine near-wall mesh WMLES simulations are these features present, exemplifying their importance in triggering a bimodal event. This motivates studies on the suppression of wake bimodality by acting upon the front separation bubbles.
How do a few Third World political movements become global causes célèbres, while most remain isolated? This book rejects dominant views that needy groups readily gain help from selfless ...nongovernmental organizations (NGOs). Instead, they face a Darwinian struggle for scarce resources where support goes to the savviest, not the neediest. Examining Mexico's Zapatista rebels and Nigeria's Ogoni ethnic group, the book draws critical conclusions about social movements, NGOs, and 'global civil society'.
Why has doping, both as a practice and a social phenomenon, been approached largely as a question of context: sport or fitness? Individuals may use substances to enhance sporting performance or ...within the framework of gym and fitness culture to create a perfect body. But clearly, people who dope are not bound to a singular context. It is quite the opposite, as individuals weave between and move across various settings in their trajectories to and from doping, as goals, identities, ambitions, and lifestyles change over time. Still, these stark categorizations often made in public discourse – and reinforced by scholars – have continued to ignore these lived experiences and limited our understanding of doping. Building on data gathered through ethnographic fieldwork, studies of online doping communities, and in-depth case studies, this book embraces the challenge of moving beyond traditional and historical doping dichotomies – such as those of sport or fitness, online or offline, pleasure or harm, masculinity or femininity, and health or harm – and, in a sociologically informed analysis, it develops new terminology to understand trajectories to and from doping. It argues there are multiple ways to understand doped bodies and doping practices, and that we must approach these questions from the perspective of both/and rather than either/or. By imploding these divisions, it offers updated and nuanced ways of both empirically and theoretically rethinking doping use and experiences attached to the practice.
Outbreak narratives have proliferated for the past quarter century, and now they have reached epidemic proportions. From28 Days Laterto24toThe Walking Dead, movies, TV shows, and books are filled ...with zombie viruses, bioengineered plagues, and disease-ravaged bands of survivors. Even news reports indulge in thrilling scenarios about potential global pandemics like SARS and Ebola. Why have outbreak narratives infected our public discourse, and how have they affected the way Americans view the world?InGoing Viral, Dahlia Schweitzer probes outbreak narratives in film, television, and a variety of other media, putting them in conversation with rhetoric from government authorities and news organizations that have capitalized on public fears about our changing world. She identifies three distinct types of outbreak narrative, each corresponding to a specific contemporary anxiety: globalization, terrorism, and the end of civilization. Schweitzer considers how these fears, stoked by both fictional outbreak narratives and official sources, have influenced the ways Americans relate to their neighbors, perceive foreigners, and regard social institutions.Looking at everything fromI Am LegendtoThe X FilestoWorld War Z, this book examines how outbreak narratives both excite and horrify us, conjuring our nightmares while letting us indulge in fantasies about fighting infected Others.Going Viralthus raises provocative questions about the cost of public paranoia and the power brokers who profit from it.Supplemental Study Materials for "Going Viral":https://www.rutgersuniversitypress.org/going-viral-dahlia-schweitzerDahlia Schweitzer- Going Viral:https://www.youtube.com/watch?v=5xF0V7WL9ow
Grow Your Creativity SkillsCreativity is a natural and renewable resource that exists in every person and helps us inspire, communicate, persevere, problem solve, rise to the occasion, and spark ...innovation. Creativity skills can be developed, nurtured, and cultivated. In the talent development context, TD professionals apply creativity to build personal capability and competitiveness, create talent opportunities, solve talent problems, and address business and learning needs for organizations. Part of the ATD Soft Skills Series, Creativity in Talent Development offers a purposeful and practical way to become more creative. This book defines creativity and outlines how you can smash organizational, team, and personal barriers, and it will have you unleashing your inner creative and inspiring creativity in others.Creativity and innovation experts Donna Porter and Nancy Tennant guide you through a creativity journey and development process to help you rediscover your curiosity and grow your abilities. Learn how to support creative habits, design environments for creativity, and master dynamic delivery for virtual events. You will be ready to use your creativity skills to ideate and initiate a new learning product or service or reimagine how the TD function operates.Included are creativity journal exercises for you to practice and develop your creativity skills. Other books in the series:Emotional Intelligence in Talent DevelopmentAdaptability in Talent DevelopmentTeamwork in Talent DevelopmentInfluence in Talent Development
Framing Terrorism Pippa Norris, Montague Kern, Marion Just / Pippa Norris, Montague Kern, Marion Just
2003, 20040802, 2004, 2004-08-02, 2003-08-22
eBook
Terrorism now dominates the headlines across the world-from New York to Kabul. Framing Terrorism argues that the headlines matter as much as the act, in political terms. Widely publicized terrorist ...incidents leave an imprint upon public opinion, muzzle the "watchdog" role of journalists and promote a general one-of-us consensus supporting security forces.
Bullying and harassment threaten academic achievement and mental health in our schools. Look beyond your work with individual students to address these problems in their larger context!
This book ...presents enlightening empirical studies and reviews of the literature on peer harassment, bullying, and victimization. Designed to expand our knowledge and understanding of these topics, Bullying, Peer Harassment, and Victimization in the Schools: The Next Generation of Prevention documents the widespread nature of the phenomena both inside and outside the United States, identifies risk and protective factors, and provides practitioners with specific, evidence-based guidelines for effective preventive action.
From the editors: The problem of bullying, peer harassment, and victimization is a serious one in our schools. It greatly affects the climate for learning and productivity and the emotional health of students and staff. This book presents empirical data and theoretical and legal case reviews to show how pervasive and serious these problems are and how they threaten both academic achievement and mental health within many of our schools. Taking a longitudinal and developmental perspective, the authors begin to outline the next generation of research in this field that will shape knowledge and practice for the next few decades. For practitioners, the book is a call to action, particularly at the school-wide level, focusing on reducing the substantial social/emotional harm done to perpetrators, bystanders, and especially, victims.
Bullying, Peer Harassment, and Victimization in the Schools provides vital information on:
what mental health professionals can do to prevent and respond to sexual harassment in schools
the relationship between middle-school adjustment and bullying
aggressive behavior and friendship patterns in immigrant children
school-based intervention strategies
the relationship between the cultur
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