scholarly journals Numerical Study of Traffic Pollutant Dispersion within Different Street Canyon Configurations

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Yucong Miao ◽  
Shuhua Liu ◽  
Yijia Zheng ◽  
Shu Wang ◽  
Yuan Li
Keyword(s):  
Software Package ◽  
Street Canyon ◽  
Numerical Study ◽  
Turbulence Models ◽  
Pollutant Dispersion ◽  
Pollution Level ◽  
Street Canyons ◽  
Urban Street ◽  
Urban Street Canyons ◽  
Computational Fluid Dynamics Cfd

The objective of this study is to numerically study flow and traffic exhaust dispersion in urban street canyons with different configurations to find out the urban-planning strategies to ease the air pollution. The Computational Fluid Dynamics (CFD) model used in this study—Open Source Field Operation and Manipulation (OpenFOAM) software package—was firstly validated against the wind-tunnel experiment data by using three differentk-εturbulence models. And then the patterns of flow and dispersion within three different kinds of street canyon configuration under the perpendicular approaching flow were numerically studied. The result showed that the width and height of building can dramatically affect the pollution level inside the street canyon. As the width or height of building increases, the pollution at the pedestrian level increases. And the asymmetric configuration (step-up or step-down street canyon) could provide better ventilation. It is recommended to design a street canyon with nonuniform configurations. And the OpenFOAM software package can be used as a reliable tool to study flows and dispersions around buildings.

Numerical Modeling of the Flow and Pollutant Dispersion in Street Canyons with Ground Thermal Effect

2014 ◽  
Vol 548-549 ◽  
pp. 601-606
Author(s):  
Ning Bo Zhang ◽  
Yan Ming Kang ◽  
Ke Zhong ◽  
Jia Ping Liu
Keyword(s):  
Thermal Effect ◽  
Street Canyon ◽  
Three Dimensional ◽  
Thermal Conditions ◽  
Pollutant Dispersion ◽  
Ambient Air ◽  
Street Canyons ◽  
Urban Street ◽  
Urban Street Canyons ◽  
Aspect Ratios

Thermal stratification affects the flow in and above urban street canyons. Such thermal effect is often not noticed, and can lead to pessimistic or optimistic results of the air quality in urban street canyons under calm conditions and low wind speeds. A three-dimensional CFD model is applied to simulate the flow patterns and particle concentrations in a street canyon under different aspect ratios and ground thermal conditions. The model is validated by the experimental data found in the literature. The simulation results are used to evaluate the flow and pollutant dispersion properties in the canyon. The results show that the ground thermal conditions can significantly affect the ventilation performance of the street canyon, which improves with the increased temperature difference (ΔT) between the ambient air and the ground of the canyon. The increased ΔT enhances the buoyancy induced secondary flow in the street canyon and hence reduce the particle concentrations in the canyon, with this influence more pronounced for small street widths.

Development and Validation of a Thermodynamic Model for Predicting Traffic-Related Pollutants Dispersion in Urban Street Canyons under Low Wind Speed Conditions

2012 ◽  
Vol 157-158 ◽  
pp. 710-713
Author(s):  
Guo Hua Gao ◽  
Jing Liu ◽  
Fei Ma ◽  
Wei Dong Luo
Keyword(s):  
Wind Speed ◽  
Thermodynamic Model ◽  
Street Canyon ◽  
Pollutant Dispersion ◽  
Shielding Effect ◽  
Street Canyons ◽  
Urban Street ◽  
Low Wind Speed ◽  
Urban Street Canyons ◽  
Pollutants Dispersion

To study the thermal effects on pollutant dispersion in the street canyon, a thermodynamic model is developed in this paper to predict surface temperature in street canyon environment, which can offer boundary conditions for CFD model. This model considered the shielding effect of buildings on solar radiation, the multi-reflection of radiation between building surfaces and the road. Furthermore, sensible heat exchange between the canyon space and the overlaying atmosphere was also modeled based on the classical theory of dynamics of atmospheric boundary layer. The reliability of this model is validated through a field measurement. Based on the thermodynamic model, a coupled calculation method is presented to predict traffic-related pollutants dispersion in urban street canyons under low wind speed conditions.

Pollutant dispersion and thermal effects in urban street canyons

1996 ◽  
Vol 30 (15) ◽  
pp. 2659-2677 ◽  
Author(s):  
Jean-François Sini ◽  
Sandrine Anquetin ◽  
Patrice G. Mestayer
Keyword(s):  
Thermal Effects ◽  
Pollutant Dispersion ◽  
Street Canyons ◽  
Urban Street ◽  
Urban Street Canyons

Characteristics of flow and reactive pollutant dispersion in urban street canyons

2015 ◽  
Vol 108 ◽  
pp. 20-31 ◽  
Author(s):  
Soo-Jin Park ◽  
Jae-Jin Kim ◽  
Minjoong J. Kim ◽  
Rokjin J. Park ◽  
Hyeong-Bin Cheong
Keyword(s):  
Pollutant Dispersion ◽  
Street Canyons ◽  
Urban Street ◽  
Urban Street Canyons ◽  
Reactive Pollutant
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