CFD modeling of traffic tidal flow: Assessment of pollutant dispersion

Pollutant distribution remains poorly understood when traffic tidal flows (TTFs) happen. By conducting computational fluid dynamic (CFD) simulations, the research efforts first focus on how different-side traffic-produced flow and turbulence (TPFT) affect in-canyon airflow corresponding pollutant dispersion. Second, composite effects of non-uniform emission TPFT are investigated. Finally, influences TTFs while varying different street canyon geometry approaching wind condition is explored. The results demonstrate that turbulent diffusion terms enhanced by movement contribute to dispersion around lanes. Besides, both-side TPFTs push leeward pollutants towards “downstream” due unidirectional advection along direction. Simultaneously considering TPFT, either leeward- or windward-congested has a higher concentration at pedestrian level close congested lane. TTF with windward congestion volume-average whole canyon. With building separation, aspect ratio, incoming direction, still result in larger accumulation above level, which nearby flow.