Computational fluid dynamics simulation of tree effects on pedestrian wind comfort in an urban area

In this study, we applied a computational fluid dynamics (CFD) model incorporating a tree drag parameterization scheme to investigate how the presence of trees improved pedestrian wind comfort on the urban campus of Pukyong National University (PKNU). We comprehensively analyzed pedestrian wind comfort considering wind inflow direction and observed frequency. To validate the CFD model, we conducted sensitivity simulations by varying the vertical profiles of leaf area density (LAD) and compared our CFD simulations with previous field measurements and simulation results. The adjusted LAD profile yielded the best reproduction of measured wind speeds and turbulent kinetic energy behind trees, demonstrating performance similar to that of a large-eddy simulation (LES) model. We applied the CFD model to investigate the effect of trees on pedestrian wind comfort on the PKNU campus. Trees markedly improved pedestrian wind comfort when horizontally incoming airflow passed through the trees; however, there was little improvement in pedestrian wind comfort in regions where airflow rapidly descended the walls of tall buildings.