Download or read book Detailed Simulations of Atmospheric Flow and Dispersion in Urban Downtown Areas by Computational Fluid Dynamics CFD Models An Application of Five CFD Models to Manhattan written by and published by . This book was released on 2006 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics (CFD) model simulations of urban boundary layers have improved so that they are useful in many types of flow and dispersion analyses. The study described here is intended to assist in planning emergency response activities related to releases of chemical or biological agents into the atmosphere in large cities such as New York City. Five CFD models (CFD-Urban, FLACS, FEM3MP, FEFLO-Urban, and Fluent-Urban) have been applied by five independent groups to the same 3-D building data and geographic domain in Manhattan, using approximately the same wind input conditions. Wind flow observations are available from the Madison Square Garden March 2005 (MSG05) field experiment. It is seen from the many side-by-side comparison plots that the CFD models simulations of near-surface wind fields generally agree with each other and with field observations, within typical atmospheric uncertainties of a factor of two. The qualitative results shown here suggest, for example, that transport of a release at street level in a large city could reach a few blocks in the upwind and crosswind directions. There are still key differences seen among the models for certain parts of the domain. Further quantitative examinations of differences among the models and the observations are necessary to understand causal relationships.

Download or read book Air Pollution Modeling and its Application XXIII written by Douw Steyn and published by Springer. This book was released on 2014-05-09 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent developments in air pollution modelling are explored as a series of contributions from researchers at the forefront of their field. This newest contribution on air pollution modelling and its application is focused on local, urban, regional and intercontinental modelling; data assimilation and air quality forecasting; model assessment and evaluation; aerosol transformation. Additionally, this work also examines the relationship between air quality and human health and the effects of climate change on air quality. The work derives from a series of papers presented at the 33rd International Technical Meeting on Air Pollution Modelling and its Application held in Miami, USA, August 27 - 31, 2013. The book is intended as reference material for students and professors interested in air pollution modelling at the graduate level as well as researchers and professionals involved in developing and utilizing air pollution models.

Download or read book Personal Spiritual Liberty written by Herbert V. Mills and published by . This book was released on 1888 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book CFD Simulations of Joint Urban Atmospheric Dispersion Field Study written by R. Lee and published by . This book was released on 2004 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The application of Computational Fluid Dynamics (CFD) to the understanding of urban wind flow and dispersion processes has gained increasing attention over recent years. While many of the simpler dispersion models are based on a set of prescribed meteorology to calculate dispersion, the CFD approach has the ability of coupling the wind field to dispersion processes. This has distinct advantages when very detailed results are required, such as for the case where the releases occur around buildings and within urban areas. CFD also has great flexibility as a testbed for turbulence models, which has important implications for atmospheric dispersion problems. In the spring of 2003, a series of dispersion field experiments (Joint Urban 2003) were conducted at Oklahoma City (Allwine, et. al, 2004). These experiments were complimentary to the URBAN 2000 field studies at Salt Lake City (Shinn, et. al, 2000) in that they will provide a second set of comprehensive field data for evaluation of CFD as well as for other dispersion models. In contrast to the URBAN 2000 experiments that were conducted entirely at night, these new field studies took place during both daytime and nighttime thus including the possibility of convective as well as stable atmospheric conditions. Initially several CFD modeling studies were performed to provide guidance for the experimental team in the selection of release sites and in the deployment of wind and concentration sensors. Also, while meteorological and concentration measurements were taken over the greater Oklahoma City urban area, our CFD calculations were focused on the near field of the release point. The proximity of the source to a large commercial building and to the neighboring buildings several of which have multistories, present a significant challenge even for CFD calculations involving grid resolutions as fine as 1 meter. A total of 10 Intensive Observations Periods (IOP's) were conducted within the 2003 field experiments. SF6 releases in the form of puffs or continuous sources were disseminated over 6 daytime and 4 nighttime episodes. Many wind and concentration sensors were used to provide wind and SF6 data over both long and short time-averaging periods. In addition to the usual near surface measurements, data depicting vertical profiles of wind and concentrations adjacent to the outside walls of several buildings were also taken. Also of interest were observations of the trajectory of balloons that were deployed close to the tracer release area. Many of the balloons released exhibit extremely quick ascents up from ground level to the top of buildings, thus implying highly convective conditions. In this paper we will present some simulations that were performed during the planning of the field experiments. The calculations were based on two possible release sites at the intersections of Sheridan and Robinson, and Broadway and Sheridan. These results provided initial information on flow and dispersion patterns, which could be used to guide optimal placement of sensors at appropriate locations. We will also discuss results of more recent simulations for several releases in which reliable data is available. These simulations will be compared with the near field data taken from the wind sensors as well as the time-averaged data from the concentration sensors. Among the other topics discussed are initial and boundary conditions used in the simulations, adaptation of building GIS data for CFD modeling and analysis of field data.

Download or read book Environmental Wind Engineering and Design of Wind Energy Structures written by Charalambos Baniotopoulos and published by Springer Science & Business Media. This book was released on 2011-12-01 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents a state-of-the-art in environmental aerodynamics and the structural design of wind energy support structures, particularly from a modern computational perspective. Examples include real-life applications dealing with pollutant dispersion in the building environment, pedestrian-level winds, comfort levels, relevant legislation and remedial measures. Design methodologies for wind energy structures include reliability assessment and code frameworks.

Download or read book CFD Modeling For Urban Air Quality Studies written by R. L. Lee and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The computational fluid dynamics (CFD) approach has been increasingly applied to many atmospheric applications, including flow over buildings and complex terrain, and dispersion of hazardous releases. However there has been much less activity on the coupling of CFD with atmospheric chemistry. Most of the atmospheric chemistry applications have been focused on the modeling of chemistry on larger spatial scales, such as global or urban airshed scale. However, the increased attentions to terrorism threats have stimulated the need of much more detailed simulations involving chemical releases within urban areas. This motivated us to develop a new CFD/coupled-chemistry capability as part of our modeling effort.

Download or read book Health Risk Assessment for Asbestos and Other Fibrous Minerals written by Andrey Korchevskiy and published by John Wiley & Sons. This book was released on 2024-07-23 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evaluates the risks and human health impacts of asbestos and other fibrous minerals Despite continuous efforts to eliminate asbestos from commercial use, it remains a serious occupational and environmental hazard. Health Risk Assessment for Asbestos and Other Fibrous Minerals provides a rigorous discussion of risk assessment methodology for elongate mineral particles, covering basics, theory, models, and practical applications, enabling readers to participate in carrying out efficient and informed health risk assessments, to estimate potential adverse effects for exposed populations, and to determine the acceptability of risks at a given level of exposure. Coverage includes: Mineralogy, health effects, pathology, exposure assessment, modeling, and characterization of risks for asbestos and similar toxic materials Necessary integration of epidemiology, toxicology, industrial hygiene, and environmental health expertise when performing a health risk assessment Emerging and not-well-known hazards, e.g. erionite and other naturally occurring fibrous minerals Contributions by Garry Burdett, Bruce Case, Lucy Darnton, Daniel Hall, Arseniy Korchevskiy, Brooke Mossman, Cassidy Strode, Robert Strode, and Ann Wylie Case studies and examples of risk calculations Health Risk Assessment for Asbestos and Other Fibrous Minerals is a highly practical reference on the subject for occupational and public health professionals, industry and government regulators, industrial hygienists, and risk assessors, along with epidemiologists, biostatisticians, toxicologists, and other scientific professionals.

Download or read book Multiscale Modeling for Process Safety Applications written by Arnab Chakrabarty and published by Butterworth-Heinemann. This book was released on 2015-11-29 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiscale Modeling for Process Safety Applications is a new reference demonstrating the implementation of multiscale modeling techniques on process safety applications. It is a valuable resource for readers interested in theoretical simulations and/or computer simulations of hazardous scenarios. As multi-scale modeling is a computational technique for solving problems involving multiple scales, such as how a flammable vapor cloud might behave if ignited, this book provides information on the fundamental topics of toxic, fire, and air explosion modeling, as well as modeling jet and pool fires using computational fluid dynamics. The book goes on to cover nanomaterial toxicity, QPSR analysis on relation of chemical structure to flash point, molecular structure and burning velocity, first principle studies of reactive chemicals, water and air reactive chemicals, and dust explosions. Chemical and process safety professionals, as well as faculty and graduate researchers, will benefit from the detailed coverage provided in this book. - Provides the only comprehensive source addressing the use of multiscale modeling in the context of process safety - Bridges multiscale modeling with process safety, enabling the reader to understand mapping between problem detail and effective usage of resources - Presents an overall picture of addressing safety problems in all levels of modeling and the latest approaches to each in the field - Features worked out examples, case studies, and a question bank to aid understanding and involvement for the reader

Download or read book Modeling Pollutant Dispersion in Urban Areas with Computational Fluid Dynamics written by Benjamin Ishii and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pollution is a major issue for urban areas all around the world. This report reviews the recent literature on modeling and pollution dispersion in urban areas with the application of computation fluid dynamic (CFD) models. A review of atmospheric turbulence and weather conditions is provided as pertaining to dispersion modeling. When applying CFD, the modeler must specify the closure model, which could be direct numerical simulation (DNS), Reynolds average numerical simulation (RANS), or large eddy simulation (LES). A comparison of the RANS and LES models is provided. The main advantages of CFD is that it offers advanced modeling that can account for turbulence under multiple weather conditions and 3-dimensional obstructions in the flow field. The recent research focuses on how CFD can be used to predict pollution concentrations without measurement devices or physically altering an urban landscape. Multiple researchers have explored pollution dispersion near roadways, specifically modeling pollution emission and the effect of roadway barriers on pollution dispersion. Other research focused on modeling a larger portion of a city where the buildings and street canyons play an important role in the flow patterns (and the effects on pollutant dispersion) within the city. The research explores the possibility of modifying urban areas to allow for increased pollutant dispersion. The recent research shows that CFD is a powerful tool for modeling pollutant dispersion and that more research is required to take full advantage of CFD in this area.

Download or read book Evaluation Study of Building resolved Urban Dispersion Models written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For effective emergency response and recovery planning, it is critically important that building-resolved urban dispersion models be evaluated using field data. Several full-physics computational fluid dynamics (CFD) models and semi-empirical building-resolved (SEB) models are being advanced and applied to simulating flow and dispersion in urban areas. To obtain an estimate of the current state-of-readiness of these classes of models, the Department of Homeland Security (DHS) funded a study to compare five CFD models and one SEB model with tracer data from the extensive Midtown Manhattan field study (MID05) conducted during August 2005 as part of the DHS Urban Dispersion Program (UDP; Allwine and Flaherty 2007). Six days of tracer and meteorological experiments were conducted over an approximately 2-km-by-2-km area in Midtown Manhattan just south of Central Park in New York City. A subset of these data was used for model evaluations. The study was conducted such that an evaluation team, independent of the six modeling teams, provided all the input data (e.g., building data, meteorological data and tracer release rates) and run conditions for each of four experimental periods simulated. Tracer concentration data for two of the four experimental periods were provided to the modeling teams for their own evaluation of their respective models to ensure proper setup and operation. Tracer data were not provided for the second two experimental periods to provide for an independent evaluation of the models. The tracer concentrations resulting from the model simulations were provided to the evaluation team in a standard format for consistency in inter-comparing model results. An overview of the model evaluation approach will be given followed by a discussion on the qualitative comparison of the respective models with the field data. Future model developments efforts needed to address modeling gaps identified from this study will also be discussed.

Download or read book Computational Fluid Dynamics for Built and Natural Environments written by Zhiqiang Zhai (John) and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces readers to the fundamentals of simulating and analyzing built and natural environments using the Computational Fluid Dynamics (CFD) method. CFD offers a powerful tool for dealing with various scientific and engineering problems and is widely used in diverse industries. This book focuses on the most important aspects of applying CFD to the study of urban, buildings, and indoor and outdoor environments. Following the logical procedure used to prepare a CFD simulation, the book covers e.g. the governing equations, boundary conditions, numerical methods, modeling of different fluid flows, and various turbulence models. Furthermore, it demonstrates how CFD can be applied to solve a range of engineering problems, providing detailed hands-on exercises on air and water flow, heat transfer, and pollution dispersion problems that typically arise in the study of buildings and environments. The book also includes practical guidance on analyzing and reporting CFD results, as well as writing CFD reports/papers.

Download or read book High Resolution CFD Simulation of Airflow and Tracer Dispersion in New York City written by S. T. Chan and published by . This book was released on 2005 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2004, a research project--the New York City Urban Dispersion Program (NYC UDP)--was launched by the Department of Homeland Security with the goal to improve the permanent network of wind stations in and around New York City and to enhance the city's emergency response capabilities. Encompassing both field studies and computer modeling, one of the program's objectives is to improve and validate urban dispersion models using the data collected from field studies and to transfer the improved capabilities to NYC emergency agencies. The first two field studies were conducted in March and August 2005 respectively and an additional study is planned for the summer of 2006. Concurrently model simulations, using simple to sophisticated computational fluid dynamics (CFD) models, have been performed to aid the planning of field studies and also to evaluate the performance of such models. Airflow and tracer dispersion in urban areas such as NYC are extremely complicated. Some of the contributing factors are complex geometry, variable terrain, coupling between local and larger scale flows, deep canyon mixing and updrafts/downdrafts caused by large buildings, street channeling and upstream transport, roof features, and heating effects, etc. Sponsored by the U.S. Department of Energy (DOE) and Department of Homeland Security (DHS), we have developed a CFD model, FEM3MP, to address some of the above complexities. Our model is based on solving the three-dimensional, time-dependent, incompressible Navier-Stokes equations with appropriate physics for modeling airflow and dispersion in the urban environment. Also utilized in the model are finite-element discretization for effective treatment of complex geometries and a semi-implicit projection method for efficient time-integration. A description of the model can be found in Gresho and Chan (1998), Chan and Stevens (2000). Predictions from our model are continuously being verified against data from field studies, such as URBAN 2000 and the Joint URBAN 2003 experiments. Modeling studies comparing simulations to observations from these field experiments are discussed in Chan et al. (2001,2004), Chan and Leach (2004), Chan and Lundquist (2005), Humphreys et al. (2004), Lundquist and Chan (2005).

Download or read book Des Waysenhauses Oeconomus Ordnung wornach der Waysenvater und die Waysenmutter sich zu verhalten haben written by and published by . This book was released on 1777 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Urban Dispersion Integrated Model written by M. Berger and published by . This book was released on 2005 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical simulations represent a unique predictive tool for understanding the three-dimensional flow fields and associated concentration distributions from contaminant releases in complex urban settings (Britter and Hanna 2003). Utilization of the most accurate urban models, based on fully three-dimensional computational fluid dynamics (CFD) that solve the Navier-Stokes equations with incorporated turbulence models, presents many challenges. We address two in this work; first, a fast but accurate way to incorporate the complex urban terrain, buildings, and other structures to enforce proper boundary conditions in the flow solution; second, ways to achieve a level of computational efficiency that allows the models to be run in an automated fashion such that they may be used for emergency response and event reconstruction applications. We have developed a new integrated urban dispersion modeling capability based on FEM3MP (Gresho and Chan 1998, Chan and Stevens 2000), a CFD model from Lawrence Livermore National Lab. The integrated capability incorporates fast embedded boundary mesh generation for geometrically complex problems and full three-dimensional Cartesian adaptive mesh refinement (AMR). Parallel AMR and embedded boundary gridding support are provided through the SAMRAI library (Wissink et al. 2001, Hornung and Kohn 2002). Embedded boundary mesh generation has been demonstrated to be an automatic, fast, and efficient approach for problem setup. It has been used for a variety of geometrically complex applications, including urban applications (Pullen et al. 2005). The key technology we introduce in this work is the application of AMR, which allows the application of high-resolution modeling to certain important features, such as individual buildings and high-resolution terrain (including important vegetative and land-use features). It also allows the urban scale model to be readily interfaced with coarser resolution meso or regional scale models. This talk will discuss details of the approach and present results for some example calculations performed in Manhattan in support of the DHS Urban Dispersion Program (UDP) using some of the tools developed as part of this new capability.

Download or read book Les Empires du Centre et la Pologne written by and published by . This book was released on 1916 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book CityFFD City Fast Fluid Dynamics Model for Urban Microclimate Simulations written by Mohammad Mortezazadeh Dorostkar and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, due to the rapid population growth and the preference to live in urban areas, urbanization has intensely increased. Currently, based on a United Nation report, 55% of the population live in the cities and the number is expected to reach about 68% by 2050. Urban microclimate has significant impacts on human life and health, and building energy performance. Urban microclimate information, such as wind velocity, temperature, humidity, pollutant dispersion levels, and local precipitation, are often important for accurate evaluations of building energy performance, indoor and outdoor human comfort, extreme events, and emergency situations. For example, it was reported that indoor temperature estimated with the microclimate information could be at least 5 °C different from that without it, which could be significant for the evaluations of indoor thermal comfort. The study of urban microclimate includes both observational and numerical approaches. The observational study is often related to field measurements, satellite imagery, and laboratory tests, e.g. in wind tunnels. The numerical approach is often based on computer models, such as CFD (computational fluid dynamics), for high-resolution and relatively small computing domains, compared to larger scale regional climate models, such as WRF and GEM-SURF. The latter two models are mostly used to model the domain size of 1~10 km with the resolution more than 100 m so they are not developed for urban microclimate and building-level simulations. In comparison, CFD has been applied to the urban microclimate of less than 1 km with a resolution less than 10 m down to the building level. However, conventional CFD solvers often perform unsatisfactorily for microscale and complicated problems because of numerical constraints such as stability issues associated with CFL condition, which is a necessary condition for convergence while solving certain partial differential equations (usually hyperbolic PDEs) numerically. Thus, conventional tools are often computationally expensive for modeling microclimates and consequently impractical for urban-scale problems. Recently, there are an increasing amount of efforts focusing on developing faster and accurate CFD techniques such as based on Fast Fluid Dynamics (FFD) methods. A FFD method relies on semi-Lagrangian and fractional step methods. FFD methods is fundamentally an explicit method without the CFL constraint so it is unconditionally stable even under large time steps and coarse grid resolutions, which are common for urban microclimate problems. In the meantime, the conventional FFD methods are often dependent on low-order interpolation schemes and thus with high numerical errors, which are the main drawbacks of this approach. The main objective of this thesis is to develop a fast and accurate CFD solver with a series of new computing algorithms based on semi-Lagrangian approach for modeling urban/city scale microclimates. The new solver with the name of CityFFD (city Fast Fluid Dynamics), is designed for tackling the challenges of large domain, coarse grid, and/or large time step, which are typical for urban microclimate simulations, without a heavy reliance on computer resources, such as the possibility of running on personal computers. First, a novel high-order interpolation scheme is proposed to significantly reduce the numerical errors of conventional semi-Lagrangian solvers. The new interpolation scheme enables the possibility of obtaining fast and accurate results even on coarse grids. The second algorithm focuses on the simulation accuracy associated with the time step of the semi-Lagrangian method. A new scheme of an adaptive time step is developed to adjust the time step dynamically according to local truncation errors. To improve the estimation of the characteristic curves, a new algorithm is proposed by considering the acceleration of the flow particles inside the computational domain which can provide highly accurate results and capture the complicated flow fields even by using a large time step. The fourth algorithm is to speed up the simulation by eliminating the need for solving the Poisson equation, which is often the most time-consuming operation of conventional semi-Lagrangian models. The new scheme is based on the concept of the artificial compressibility of solving incompressible flows and makes it easier to implement parallel computing techniques, such as the NVIDIA GPU CUDA and the OpenMP. The last feature of CityFFD is adding Large Eddy Simulation (LES) model to capture the turbulence behavior of the flow in urban environments. In this section, a parallel OpenMP geometry reader is developed to read the city scale geometries in a fast manner. At the end, the proposed CityFFD model is demonstrated by a case study: the modeling of an extreme weather event, the snow-storm of the century in Montreal, for evaluating building resilience during the storm, to show the importance of urban microclimate and its impact on human health and indoor environment.

Download or read book Constitutiones Clementis V Pape una cum apparatu Joannis Andree written by and published by . This book was released on 1485 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: