CFD simulations on Vertical Forest’s Effects in a Step-up Street Canyon

Abstract

The expansion of urban areas has heightened air pollution and exacerbated the urban heat island effect, giving rise to urgent environmental and health challenges. In dense urban landscapes where traditional urban greening solutions prove insufficient, the adoption of vertical forests, incorporating vegetation on building facades, balconies, and rooftops, has emerged as a critical strategy. These innovative green spaces plays a particularly vital role in street canyons, where they have possess the potential to significantly impact air quality and thermal comfort. We conducted an investigation into the effects of vertical forests on airflow and pollutant dispersion in step-up street canyons, utilizing dry deposition in a computational fluid dynamics (CFD) model. For validation, we compared the performance of the dry deposition effect in the CFD model with a wind tunnel experiment. Despite a substantial reduction in fine particles through dry deposition, there was an observed increase of 20-25% in fine particle concentrations within lower layer of the street canyon. This increase was attributed to a 14-20% reduction in wind speed in the street canyon. Acknowledgments This research was supported by Particulate Matter Management Specialized Graduate Program through the Korea Environmental Industry & Technology Institute(KEITI) funded by the Ministry of Environment(MOE)