CFD modeling using RANS and LES of pollutant dispersion in a three-dimensional street canyon is investigated by comparison with measurements. The purpose of this study is to confirm the accuracy of LES in modeling plume dispersion in a simple street canyon model and to clarify the mechanism of the discrepancy in relation to RANS computation. Simple LES modeling is shown by comparison with wind ...

The world is facing problems of increased atmospheric pollution, climate change and global warming effects. Innovative technologies to identify, quantify and assess fluxes exchange of the pollutant gases between Earth’s surface and atmosphere are required. This paper proposes the development and integration of an inexpensive airborne system capable of monitoring pollutant gases collecting data ...

This study compared dispersion calculations using a street network model (SIRANE) with results from wind tunnel experiments in order to examine model performance in simulating short-range pollutant dispersion in urban areas. The comparison was performed using a range of methodologies, from simple graphical comparisons (e.g. scatter plots) to more advanced statistical analyses. A preliminary ana...

Vehicle emissions of nitrogen oxides (NOx), carbon monoxide (CO), fine particulate matter (PM2.5), organic aerosol (OA), and black carbon (BC) were measured at the Caldecott tunnel in the San Francisco Bay Area. Measurements were made in bore 2 of the tunnel, where light-duty (LD) vehicles accounted for >99% of total traffic and heavy-duty trucks were not allowed. Prior emission studies conduct...

Some urban road tunnels serve as the main traffic access routes for residents in surrounding large communities. The congestion is a common phenomenon during rush hours inside this kind of tunnel. In order to learn about environmental parameters tunnel evening hour, comprehensive measurement typical commuting conducted. thermal environment and air pollutant distribution along are measured simult...

Interunit dispersion problems have been studied previously mainly through on-site measurements, wind tunnel tests, and CFD simulations. In this study, a scaled outdoor experiment was conducted to examine the interunit characteristics in consecutive two-dimensional street canyons. Tracer gas ( CO 2 ) continuously released simulate pollutant routes between rooms The reentry ratio analyzed reveal ...

The influence of vegetation on the concentrations of traffic pollutants in urban street canyons is examined using numerical simulations with the CFD code OpenFOAM. This CFD approach is validated against literature wind tunnel data on traffic pollutant dispersion in street canyons. The impact of avenues of trees is simulated for a variety of vegetation types and the full range of approaching win...

Air moving into the open end of a passive sampler affects the pollutant mass transfer by generating eddies leading to a reduction in the molecular diffusion length and a consequent overestimation of the pollutant concentration. This decrease is found to be experimentaly in the range of 10-40 % depending on the wind speed at the site. Assuming that the eddy turbulence is isotropic and the horizo...