Download or read book Flow and Turbulence in Urban Roughness Canopies written by Dragan Zajic and published by . This book was released on 2006 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow and Transport Processes with Complex Obstructions written by Yevgeny A. Gayev and published by Springer Science & Business Media. This book was released on 2007-02-06 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book that reviews problems in different fluid mechanics disciplines that led to the concept of canopy, or penetrable roughness. Despite their diversity, many flows may be theoretically united by means of introducing distributed sinks and/or sources of momentum and heat and mass. These and other flows in engineering and environmental situations over surfaces with many obstacles are reviewed in terms of general concepts of fluid mechanics.
Download or read book Urban Climates written by T. R. Oke and published by Cambridge University Press. This book was released on 2017-09-14 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: Urban Climates is the first full synthesis of modern scientific and applied research on urban climates. The book begins with an outline of what constitutes an urban ecosystem. It develops a comprehensive terminology for the subject using scale and surface classification as key constructs. It explains the physical principles governing the creation of distinct urban climates, such as airflow around buildings, the heat island, precipitation modification and air pollution, and it then illustrates how this knowledge can be applied to moderate the undesirable consequences of urban development and help create more sustainable and resilient cities. With urban climate science now a fully-fledged field, this timely book fulfills the need to bring together the disparate parts of climate research on cities into a coherent framework. It is an ideal resource for students and researchers in fields such as climatology, urban hydrology, air quality, environmental engineering and urban design.
Download or read book Turbulence Within and Above Real and Artificial Urban Canopies written by and published by . This book was released on 2004 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the turbulence characteristics of ASL flow in and through urban areas is essential to predicting dispersion in cities. Urban areas, however, alter the inherent turbulence found in the Atmospheric Surface Layer (ASL) through a variety of mechanisms. Due to the difficulty in obtaining characteristic measurements of the turbulence in actual urban areas, simplified models (usually wind tunnel models) are typically used to isolate the mechanisms affecting turbulence characteristics in and around buildings or groups of buildings. Results from these simplified models are often used to validate computational models. These models are in turn used to predict the turbulence and flow characteristics in actual urban areas that have complex geometries and topography based on a limited amount of data found in the urban area. The depth of the ASL is typically much larger than most buildings making it possible to consider urban areas as surface roughness at large scales. At large scales the urban area therefore produces a flow regime above an urban area (in the inertial sublayer and above) that is basically an ASL flow that has been modified by the presence of the urban terrain below it. It can be argued that the flow regime transitions to a bluff body flow that is influenced by the upstream ASL conditions surrounding it through the Urban Roughness Sublayer (URSL) and into the Urban Canopy (UC). In these regimes it is rational to expect that the bluff body flow characteristics (i.e. wake and recirculation regions, vortex shedding, etc.) impose scales in the flow that affect the turbulence and transfer of energy between eddies of different sizes. Thus a detailed understanding of these phenomena is, for example, necessary to accurately validate high-resolution computational models. This paper compares sonic anemometer data obtained in an actual urban area during the Joint Urban 2003 (JU03) Field Experiment with those data obtained in a simulated urban area during the Mock Urban Setting Test (MUST). JU03 was held in downtown Oklahoma City in a street canyon, while MUST was performed around an array of aligned, same-size obstacles simulating an urban area at near full scale. These experiments, both performed in a true ASL, provide an opportunity to compare turbulence and flow characteristics produced by an actual urban canyon with semi-complex geometry and those found in a simulated urban canyon with a highly simplified geometry. Local effects were found to dominate the flow in the lowest 10% of the canyon, often producing predominantly positive along-wind to vertical cospecta and large variations in the mean turbulence statistics. A complicated flow structure was found in the canyon with large mean vertical velocity components. Local phenomena were found also found to dramatically affect the energy cascade in some cases by adding energy over discrete bandwidths or altering the slope of the spectra in the high frequency range from the typical f−53 behavior of the inertial subrange.
Download or read book Turbulence Within and Above an Urban Canopy written by Mathias W. Rotach and published by . This book was released on 1991 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shallow Flows written by Gerhard H. Jirka and published by CRC Press. This book was released on 2004-09-15 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text presents the key findings of the International Symposium held in Delft in 2003, which explored the process of shallow flows. Shallow flows are found in lowland rivers, lakes, estuaries, bays, coastal areas and in density-stratified atmospheres, and may be observed in puddles, as in oceans. They impact on the life and work of a w
Download or read book Application of the Ideal Canopy Flow Concept to Natural and Artificial Roughness Elements written by R. M. Cionco and published by . This book was released on 1971 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effort has been expended in modeling air flow within and above simple roughness elements for neutral steady-state conditions. Application of the ideal canopy flow concept suggested by Cionco, Ohmstede and Appleby is now extended to various natural and artificial canopies of simple or complex structure. Properties and characteristics considered were: Shape of the unit canopy wind profile, intensity of turbulence magnitudes, an index of canopy flow, and the effects of density and flexibility variations upon the flow. The profile shape is characteristic and best described by an exponential relationship within simple-structured elements. In complex structures, the profiles exhibited low-level maximums and no-gradient layers. Above the vegetation, the logarithmic wind relation was valid for each canopy type. Intensity of turbulence was relatively uniform with height for simple canopies and significantly non-uniform with height in complex structures, with large leaf area maximums and very low wind speeds. The ideal canopy flow concept can potentially serve many disciplines and efforts besides micrometeorology and diffusion research. If to serve no other purpose, it can be used to establish the initial formulation of a boundary condition or minor portion of a larger problem. The mathematical simplicity of the concept may be its most important quality when it is to be used as part of a larger system of equations.
Download or read book Annual Research Briefs written by Center for Turbulence Research (U.S.) and published by . This book was released on 2010 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Eddy Covariance written by Marc Aubinet and published by Springer Science & Business Media. This book was released on 2012-01-18 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: This highly practical handbook is an exhaustive treatment of eddy covariance measurement that will be of keen interest to scientists who are not necessarily specialists in micrometeorology. The chapters cover measuring fluxes using eddy covariance technique, from the tower installation and system dimensioning to data collection, correction and analysis. With a state-of-the-art perspective, the authors examine the latest techniques and address the most up-to-date methods for data processing and quality control. The chapters provide answers to data treatment problems including data filtering, footprint analysis, data gap filling, uncertainty evaluation, and flux separation, among others. The authors cover the application of measurement techniques in different ecosystems such as forest, crops, grassland, wetland, lakes and rivers, and urban areas, highlighting peculiarities, specific practices and methods to be considered. The book also covers what to do when you have all your data, summarizing the objectives of a database as well as using case studies of the CarboEurope and FLUXNET databases to demonstrate the way they should be maintained and managed. Policies for data use, exchange and publication are also discussed and proposed. This one compendium is a valuable source of information on eddy covariance measurement that allows readers to make rational and relevant choices in positioning, dimensioning, installing and maintaining an eddy covariance site; collecting, treating, correcting and analyzing eddy covariance data; and scaling up eddy flux measurements to annual scale and evaluating their uncertainty.
Download or read book Turbulence Models and Their Application in Hydraulics written by Wolfgang Rodi and published by . This book was released on 1984 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Comparison Between a First Order Closure Model for Disturbed Urban Canopy Flows with Observations for Mean Wind and Turbulence written by and published by . This book was released on 2001 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two canopy windflow models (basic model and alternative model) are described and assessed against measurements of mean wind and turbulence in a wide range of canopies (both vegetative and urban). The windflow models are based on a first-order turbulence closure for the description of both the mean wind (U) and kinetic energy of turbulence (kappa), viz. Reynolds' equations are closed using eddy-viscosity K lambda kappa 1/2, where lambda is an algebraically specified turbulence length scale. The windflow models are compared with eleven different canopy flows (aeroelastic plant canopy; corn canopy; square and staggered arrays of cubical obstacles at three different frontal area densities 0.0625, 0.16, AND 0.44; square and staggered arrays of billboard-shaped obstacles at a frontal area density of 0.16; and, the Tombstone canopy). Comparisons of model predictions with these different canopies show that the alternative windflow model gives the best overall conformance with respect to both mean flow and turbulence profiles. The basic windflow model was found to underpredict the turbulence kinetic energy within the canopy, although this underprediction does not appear to affect its reasonably good predictions of the mean wind speed and the shear stress. However, both the basic and alternative windflow models underpredict severely the magnitude of the mean wind shear at the canopy top for 'urban' canopies at the highest frontal area density 0.44 investigated. It is suggested that the alternative windflow model can be used probably unmodified (viz., without resorting to tuning of any model constants) for the simulation of a wide range of canopy flows provided the frontal area densities of the 'urban' canopies are not so large as to provoke skimming flow.
Download or read book A One Dimensional Mean Wind and Turbulence Model for a Uniform Urban Canopy written by Eugene C. Yee and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents a fully analytical model for the prediction of the one-dimensional mean wind speed, kinematic shear stress, turbulence kinetic energy, and velocity variances in a horizontally homogeneous canopy. The model was developed originally for vegetative canopies such as forests, but is applied in the report to urban canopies. The report shows how to derive analytical expressions for the within-canopy velocity variances using two methods: equilibrium partitioning and algebraic stress model partitioning. Model predictions are compared with some measurements of mean flow & turbulence statistics obtained in two urban canopies. The results show the degree of success of the model in providing estimates of a number of important flow quantities. The model provides all the statistics of the wind field required as input to drive a physically-based model for the prediction of urban dispersion of contaminants.
Download or read book Outdoor Human Comfort and Its Assessment written by Task Committee on Outdoor Human Comfort and published by ASCE Publications. This book was released on 2004-01-01 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prepared by the Task Committee on Outdoor Human Comfort of the Aerodynamics Committee of the Aerospace Division of ASCE This report describes state-of-the-art methods for assessing and improving outdoor human comfort. Factors affecting outdoor comfort are wind, air temperature, humidity, sun, and precipitation. Wind, in particular, is greatly affected by large buildings, and many modern developments are wind-tunnel tested to examine how wind flows around new buildings will affect pedestrians. This report discusses testing methods and criteria for assessing comfort and safety. Criteria are expressed in terms of both threshold wind speeds for discomfort and also the percentage of time that conditions should be below those thresholds. Historically, wind and its mechanical effects?such as picking up dust, impairing balance, or blowing people over?were the factors receiving the most attention. More recently, however, methods have been developed to address other factors, such as solar radiation, air temperature, and humidity. Topics include: elements of the microclimate; methods of determining wind conditions; wind criteria and control measures; and assessing thermal comfort.
Download or read book Atmospheric Boundary Layer Flows written by J. C. Kaimal and published by Oxford University Press, USA. This book was released on 1994 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text gives a simple view of the structure of the boundary layer, the instruments available for measuring its mean and turbulent properties, how best to make the measurements, and ways to process and analyze the data.
Download or read book The Method of Volume Averaging written by S. Whitaker and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiphase systems dominate nearly every area of science and technology, and the method of volume averaging provides a rigorous foundation for the analysis of these systems. The development is based on classical continuum physics, and it provides both the spatially smoothed equations and a method of predicting the effective transport coefficients that appear in those equations. The text is based on a ten-week graduate course that has been taught for more than 20 years at the University of California at Davis and at other universities around the world. Problems dealing with both the theoretical foundations and the applications are included with each chapter, and detailed solutions for all problems are available from the author. The course has attracted participants from chemical engineering, mechanical engineering, civil engineering, hydrologic science, mathematics, chemistry and physics.
Download or read book Climate Change and Terrestrial Ecosystem Modeling written by Gordon Bonan and published by Cambridge University Press. This book was released on 2019-02-21 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an essential introduction to modeling terrestrial ecosystems in Earth system models for graduate students and researchers.
Download or read book A One dimensional Mean Wind and Turbulence Model for a Uniform Urban Canopy written by and published by . This book was released on 2000 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents a fully analytical model for the prediction of the one-dimensional mean wind speed, kinematic shear stress, turbulence kinetic energy, and velocity variances in a horizontally homogeneous canopy. The model was developed originally for vegetative canopies such as forests, but is applied in the report to urban canopies. The report shows how to derive analytical expressions for the within-canopy velocity variances using two methods: equilibrium partitioning and algebraic stress model partitioning. Model predictions are compared with some measurements of mean flow & turbulence statistics obtained in two urban canopies. The results show the degree of success of the model in providing estimates of a number of important flow quantities. The model provides all the statistics of the wind field required as input to drive a physically-based model for the prediction of urban dispersion of contaminants.
