Journal ArticleDOI
The modelling of turbulence from traffic in urban dispersion models: Part I: Theoretical considerations
TLDR
In this article, a theoretical framework to estimate mechanical turbulence induced by traffic in street canyons at low wind speed conditions is established, where the standard deviation of the velocity fluctuations is adopted as a measure of traffic-produced turbulence.Abstract:
The modelling of pollutant dispersion at the street scale in an urban environment requires the knowledge of turbulence generated by the traffic motion in streets. In this paper, a theoretical framework to estimate mechanical turbulence induced by traffic in street canyons at low wind speed conditions is established. The standard deviation of the velocity fluctuations is adopted as a measure of traffic-produced turbulence (TPT). Based on the balance between turbulent kinetic energy production and dissipation, three different parameterisations for TPT suitable for different traffic flow conditions are derived and discussed. These formulae rely on the calculations of constants that need to be estimated on the basis of experimental data. One such estimate has been made with the help of a wind tunnel data set corresponding to intermediate traffic densities, which is the most common regime, with interacting vehicle wakes.read more
Citations
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Journal ArticleDOI
Flow and dispersion in urban areas
Rex Britter,Steven R. Hanna +1 more
TL;DR: In this article, the authors address flow and dispersion in urban areas at four scales: regional, city, neighborhood, and street, and address the most appropriate framework to study and quantify the result.
Journal ArticleDOI
Dispersion study in a street canyon with tree planting by means of wind tunnel and numerical investigations – Evaluation of CFD data with experimental data
TL;DR: In this paper, the influence of tree planting with different tree crown porosity was investigated and the results obtained in this work by combining wind tunnel experiments and CFD based simulations suggest ways to obtain quantitative information for assessment, planning and implementation of exposure mitigation using trees in urban street canyons.
Journal ArticleDOI
Dynamics and dispersion modelling of nanoparticles from road traffic in the urban atmospheric environment--A review
TL;DR: A review of the current practices of nanoparticle dispersion modelling at five local scales (i.e., vehicle wake, street canyons, neighbourhood, city and road tunnels) is presented in this article.
Journal ArticleDOI
Progress in observing and modelling the urban boundary layer
TL;DR: In this article, the authors consider progress made in studies of the urban boundary layer (UBL) in terms of a conceptual framework spanning microscale to mesoscale determinants of UBL structure and evolution.
Journal ArticleDOI
Climate and more sustainable cities: climate information for improved planning and management of cities (producers/capabilities perspective)
C. S. B. Grimmond,Matthias Roth,Timothy R. Oke,Y. C. Au,Martin Best,Richard Betts,Gregory R. Carmichael,Helen A. Cleugh,Walter F. Dabberdt,Rohinton Emmanuel,Edmilson Dias de Freitas,Krzysztof Fortuniak,Steven R. Hanna,Petra M. Klein,Laurence S. Kalkstein,C. H. Liu,Alex Nickson,David Pearlmutter,David J. Sailor,James A. Voogt +19 more
TL;DR: In the last two decades substantial advances have been made in the understanding of the scientific basis of urban climates as discussed by the authors, with attention to sustainability of cities, applications that use climate information, and scientific understanding in relation to measurements and modelling.
References
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Book
Engineering Fluid Mechanics
TL;DR: In this article, the authors present an approach for the analysis of flow properties and properties in a 3D manifold with respect to velocity, acceleration, and velocity distribution, and the Bernoulli Equation.
Journal ArticleDOI
Pollutant dispersion and thermal effects in urban street canyons
TL;DR: In this paper, a numerical model has been built to simulate the small-scale atmospheric flows within the urban canopy, based on the lower atmosphere classical assumptions and the standard κ-ϵ” two-equation turbulence model.
Book ChapterDOI
Ospm - a parameterised street pollution model
TL;DR: The Danish Operational Street Pollution Model (OSPM) as discussed by the authors uses a combination of a plume model for the direct contribution and a box model for recirculating part of the pollutants in the street.
Journal ArticleDOI
Mean Flow and Turbulence Characteristics in an Urban Roughness Sublayer
TL;DR: In this paper, a detailed model of an urban landscape has been re-constructed in the wind tunnel and the flow structure inside and above the urban canopy has been investigated, and an extensive analysis of the measured meanflow and turbulence profiles carried out.
Journal ArticleDOI
Profiles of turbulence statistics in and above an urban street canyon
TL;DR: In this paper, the authors present an extensive urban climate study, which consists of 18 months of continuous measurements of mean variables and a total of 131 runs of turbulence measurements at various heights within and above an urban street canyon.