The effect of exhaust emissions from a group of moving vehicles on pollutant dispersion in the street canyons

2020 ◽  
Vol 181 ◽  
pp. 107120 ◽  
Author(s):  
Tianhao Shi ◽  
Tingzhen Ming ◽  
Yongjia Wu ◽  
Chong Peng ◽  
Yueping Fang ◽  
...  
Keyword(s):  
Pollutant Dispersion ◽  
Exhaust Emissions ◽  
Street Canyons ◽  
Moving Vehicles

Large-Eddy Simulation of Reactive Pollutant Dispersion Over Street Canyons of Different Aspect Ratios

2014 ◽  
Author(s):  
T. Z. Du ◽  
Chun-Ho Liu ◽  
Y. B. Zhao
Keyword(s):  
Aspect Ratio ◽  
Large Eddy Simulation ◽  
Chemical Reactions ◽  
Pollutant Dispersion ◽  
Pollutant Removal ◽  
Street Canyons ◽  
Eddy Simulation ◽  
Aspect Ratios ◽  
Large Eddy ◽  
Reactive Pollutant

In urban areas, pollutants are emitted from vehicles then disperse from the ground level to the downstream urban canopy layer (UCL) under the effect of the prevailing wind. For a hypothetical urban area in the form of idealized street canyons, the building-height-to-street-width (aspect) ratio (AR) changes the ground roughness which in turn leads to different turbulent airflow features. Turbulence is considered an important factor for the removal of reactive pollutants by means of dispersion/dilution and chemical reactions. Three values of aspect ratio, covering most flow scenarios of urban street canyons, are employed in this study. The pollutant dispersion and reaction are calculated using large-eddy simulation (LES) with chemical reactions. Turbulence timescale and reaction timescale at every single point of the UCL domain are calculated to examine the pollutant removal. The characteristic mechanism of reactive pollutant dispersion over street canyons will be reported in the conference.

scholarly journals Effect of traffic tidal flow on pollutant dispersion in various street canyons and corresponding mitigation strategies

2020 ◽  
Vol 1 (3) ◽  
pp. 242-253 ◽  
Author(s):  
Zhengtong Li ◽  
Tianhao Shi ◽  
Yongjia Wu ◽  
Hao Zhang ◽  
Yu-Hsuan Juan ◽  
...  
Keyword(s):  
Tidal Flow ◽  
Pollutant Dispersion ◽  
Mitigation Strategies ◽  
Street Canyons

The effect of turbulence induced by different kinds of moving vehicles in street canyons

2020 ◽  
Vol 54 ◽  
pp. 102015 ◽  
Author(s):  
Cunjin Cai ◽  
Tingzhen Ming ◽  
Weijie Fang ◽  
Renaud de Richter ◽  
Chong Peng
Keyword(s):  
Street Canyons ◽  
Moving Vehicles

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

scholarly journals Numerical simulation of pollutant dispersion in urban roadway tunnels

2017 ◽  
Vol 9 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Jingliang Dong ◽  
Yao Tao ◽  
Yimin Xiao ◽  
Jiyuan Tu
Keyword(s):  
Air Quality ◽  
Traffic Congestion ◽  
Pollutant Dispersion ◽  
Piston Effect ◽  
Traffic Jam ◽  
Traffic Conditions ◽  
Toxic Emissions ◽  
Driving Speed ◽  
Moving Vehicles ◽  
Short Tunnel

Vehicular toxic emissions can easily contaminate the air quality of the enclosed tunnel environment, especially during rush hours with traffic jam events or low vehicle speeds, which poses serious health hazards to road utilizers. The piston effect generated by moving vehicles was normally considered adequate to discharge vitiated air out of short tunnel based on a typical driving speed. However, complex traffic conditions may yield unexpected consequences on in-tunnel air quality levels. This study numerically investigated the CO2 concentration to identify the in-tunnel pollutant dispersion under three traffic conditions including severe traffic congestion and traffic flow with low vehicle speeds. Fan conditions were considered to model the influence of mechanical winds on pollutant dispersion and comparison with vehicular piston effect was also performed. The results revealed elevated pollutant concentration regions were found at the vicinity of near-ground region and tunnel downstream. The vehicular piston effect can sufficiently remove the in-tunnel vehicular emissions when vehicles travel at relatively higher speed. However, pollutant accumulation occurs when vehicles are idling or moving at slow speed. Compared with traffic piston effect at high travelling speed, the mechanical ventilation of ceiling mounted fans only generate a limited contribution to the removal of emissions.

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