CFD evaluation of mean and turbulent wind characteristics around a high-rise building affected by its surroundings

Abstract

This study comprehensively investigated the accuracy of computational fluid dynamics (CFD) simulations for predicting the mean and turbulent wind characteristics around a high-rise building surrounded by low-rise street canyons. The flow field was characterized based on the complicated interaction between a high-rise building and its surrounding buildings, which has rarely been examined in previous CFD studies. We obtained the CFD results using steady Reynolds averaged Navier-Stokes equation (RANS) models and large eddy simulations (LES), which were compared with the measurement results obtained via wind tunnel experiments. Furthermore, we quantitatively investigated the impact of the presence of a high-rise building on the prediction accuracy of pedestrian wind environments, including the gust wind velocity. The results showed that the performance of both LES and RANS decreased in the presence of a high-rise building, indicating that predicting the flow around a high-rise building is more challenging than predicting the flow of a simple street canyon. Additionally, the prediction accuracies of RANS and LES for the mean wind velocity at the pedestrian level were similar in regions with high wind velocity. However, the prediction accuracy of LES in the medium- and low-wind-velocity regions was significantly better than that of RANS, which is closely related to the superior prediction accuracy of turbulent kinetic energy in LES. Although LES can predict the gust wind velocity directly with higher accuracy than that of RANS by using a gust factor, RANS can be used to predict the gust wind velocity with a certain accuracy using a peak factor.