The influence of moving vehicle wakes on the effectiveness of roadside barriers in residential canyons utilising moving reference frames

Abstract

Traditional vehicular urban canyon models often overlook the kinetic energy contribution of moving vehicles, which can misrepresent flow conditions at pedestrian level. This research aims to investigate vehicle-induced airflows in residential canyons while maintaining computational complexity to a minimum using CFD simulations with a moving reference frame. Results show that traffic movement is the dominant driver of street-level air currents even at speeds as low as 30 km/h, inducing a lateral flow pattern rather than a standard urban canyon circulating vortex. The performance in attenuating such airflows of 0.5 m and 1 m high roadside barriers is then evaluated and results demonstrate that these barriers effectively shield pedestrian zones by disrupting the lateral flow. Under these symmetric, lateral conditions, roadside barriers exhibit higher reliability compared to their performance in standard urban canyon flows with negligible vehicle effects. These findings suggest that traffic movement must be integrated with aerodynamic assessments to accurately optimize urban microclimate interventions in areas of high traffic throughput.