Interference effect on flow features and aerodynamic mechanism over the roof between two tall buildings

Interference effect of an upwind building on flow features and wind power potential over roof of principal building was investigated through numerical simulations. Flow features were examined at different wind directions and spacing ratios (d/B = 2, 3, 4, 5, and 6), and associated aerodynamic mechanisms were analyzed. Turbulence intensity was less affected by interfering building than mean velocity. d/B exerted a more important impact on mean velocity at θ = 0° and 180° than those at oblique wind directions. The isolated building had large power potential at leeward locations due to strong flow separation at θ = 0° compared with principal building. The largest skew angle β_max fluctuated greatly with roof locations (from −15° to 80°) of isolated building at θ = 0°. In comparison, β_max over principal building changed slightly with roof locations (from −16° to 3°) due to smooth flow separation and reattachment at θ = 0°. Effect of d/B on the largest wind energy and hub height of roof-mounted wind turbines depended on θ. Recommendations for the siting of HAWTs on roofs were finally provided.