Numerical simulation of wind flow characteristics over a large-scale complex terrain: A computational fluid dynamics (CFD) approach

Growth of the city's population induces changes to airflow and pollutant and dust dispersion process, which is significantly affected by barriers and consequently influences human health and life. Therefore, it is necessary to investigate the airflow pattern using simulation approaches. In this study, the computational fluid dynamics (CFD) using the Reynolds Averaged Navier-Stokes (RANS) equations as a powerful numerical modeling tool, and Log-law and Power-law empirical models, along with several auxiliary data (DEM data) and several relevant software tools (Google Mapper, Sketchup 17, Rhinoceros 5, and Solid Works 19) were employed to simulate wind velocity and pressure distributions over a large-scale complex terrain and buildings in Gouyom to Shahrak-e Golestan, Shiraz, Iran. Validation procedure was performed through monthly measured wind velocity at seven elevations of 3, 6, 9, 10, 12, 15, and 18 m in three representative locations over a year using a digital handheld anemometer (UNI-T UT361) that was capable to measure wind velocity in the range of 2 to 30 m s-1 with an accuracy of 3%+0.5 The CFD results better agreed with the experimental data in real situations than those of the other two applied numerical models (Power-law and Log-law). Furthermore, wind velocity in three prescribed lines of different heights (5 m, 10 m, and 20 m) with different topographies and buildings had more fluctuations from the beginning of the study area to nearly 6 km. The turbulence intensity profiles also confirmed the mentioned issues. Results revealed that the minimum and maximum pressures were observed in the crest and flat surfaces, respectively. The CFD numerical simulation approach is recommended to predict airflow characteristics (wind velocity and pressure distributions), model soil erosion by wind, and present solutions to reduce the airflow pattern change-induced hazards.