Flow instabilities within an urban intersection

Turbulent flow inside street canyons was studied using Laser Doppler Velocimetry (LDV) in wind–tunnel experiment. Spatial distribution of momentum flux and moments of third and fourth order of velocity components obtained from one–point measurement are investigated. The area of interest covers an inner part of street canyon and adjacent intersection. Time–averaged momentum flux is divided into particular quadrants using Quadrant Analysis method. Comparison between flux events and skewness provides some insight into the spatial distribution of strong intermittent tendency. Therefore, we can explain better the spatially local dominance of sweep, respectively ejection that corresponds to intermittent gust moving inward, respectively outward from canyon.

Keywords: wind tunnels, street canyons, flow instability, urban intersections, environmental pollution, quadrant analysis, turbulent flow, intermittent gusts