Pedestrian-level wind distributions simulation using an integrated method of WRF, GIS, and CFD in real urban environments

Accurate inflow wind profiles are essential for computational fluid dynamics (CFD) simulations to calculate wind distributions in real urban environments. The Weather Research and Forecasting (WRF) model is widely used to provide realistic inflow wind profiles, as it captures atmospheric phenomena such as diurnal variations and sea breezes. However, WRF simulations are not sufficiently precise to predict wind profiles in built-up areas, due to the oversimplification of the complex urban morphology. Our previous study has proposed an analytical method combining WRF with a porosity model for accurately estimating urban wind profiles in the built-up areas. In this study, we further evaluated a multiscale modelling approach combining CFD simulations with inflow wind profiles estimated using the analytical method (analytical-inlet-CFD) for calculating pedestrian-level wind distributions. A public housing estate covering an area of 578 m × 560 m was selected as the target area, and field measurements were conducted at two sampling points, the landscape garden and the plaza, to collect pedestrian-level wind data in this real urban environment. The collected data then served as the benchmark for evaluating the accuracy of the analytical-inlet-CFD in outdoor wind simulations. For comparison, CFD simulations using inflow boundary conditions directly extracted from WRF (WRF-inlet-CFD) were also included. For both methods of setting the inflow boundary conditions of CFD simulations, wind profiles within the urban canopy were approximated using an exponential distribution. The results showed that analytical-inlet-CFD performed better than WRF-inlet-CFD in calculating pedestrian-level wind distributions in real urban environments.