Establishing Correlation between Flow Structures and Air Pollutant Dispersion around Isolated Building

Air pollutant dispersion around buildings is highly complex due to the interactions between turbulent wind flows and air pollutants. Predicting and managing air pollutant concentrations in built-up areas depends on an accurate understanding of the impacts of turbulent wind on air pollutant dispersion. This study revealed the correlation between turbulent wind and pollutant fields around isolated buildings by using large eddy simulation (LES), proper orthogonal decomposition (POD), extended proper orthogonal decomposition (EPOD), and contribution analyses. This study modeled five isolated buildings with different height-to-width ratios (AR) ranging from 4 to 0.33 to reveal the impact of building geometries on the turbulent wind field and, subsequently, on the pollutant field. POD and EPOD identified the synchronized pollutant dispersion patterns with the dominant wind flow features. The contribution analysis estimated the contribution of the dominant flow features to pollutant dispersion. The analyses revealed that the staggered and symmetrically arranged spanwise vortices dispersed air pollutants in the building wake in spanwise and streamwise directions. The contribution of the symmetrically arranged spanwise vortices to air pollutant dispersion reached the maximum of 98% for the tall building with AR = 4 because of the intense and large vortices in its wake.