Using a CFD approach for the study of street-level winds in a built-up area

The street-level winds in a built-up area are simulated numerically using a conventional method that is commonly applied in the industry. The method is described in terms of computational domain, grid density, turbulence model and boundary conditions. Testing of the domain size and the grid density is also conducted to minimize the numerical errors and the computed values are compared with the wind tunnel data available from a previous study. The computed values agree favourably with the measured values in the case of H/h=1 where all the buildings have the same height. In other cases (H/h=2 and 4) where the central building is taller than its surrounding blocks, the agreement between the computation and experiment becomes relatively unsatisfactory. The accuracy requirement of using CFD in the environmental wind studies is discussed and this study suggests that applying the relatively simple CFD approach is adequate to investigate the street-level winds during the phase of preliminary design while more attention is required when the building layout becomes complicated.