Large Eddy Simulation of wind flow impact on fire-induced indoor and outdoor air pollution in an idealized street canyon

The Fire Dynamics Simulator (FDS) using the Large Eddy Simulation (LES) method was employed to investigate the effects of wind on plume dispersion generated by compartment fire and the level of air pollution inside an idealized street canyon and the surrounding buildings. The purpose of this study was to assess the exposure of the occupants in building compartments with openings oriented towards the street and for the pedestrians on the street at ground level. The numerical results indicate that there is strong interaction between wind flow and in-canyon fire plume flow. The flow field patterns in the canyon restrict the air inflow, cause the fire plume dispersion inside and over the canyon, and push the smoke into the building compartments. Larger quantities of air in the fire compartment result in lower concentrations of carbon monoxide, higher concentrations of carbon dioxide, and smoke dilution. Larger quantities of air in the outer plume, due to the dilution effect, reduce the concentrations and temperature of the pollutants in the street and the buildings. These results can be used not only to assess the air pollution level under extreme conditions such as a fire accident, but also in urban planning and air quality control strategies aimed at reducing the air pollution level within urban areas.