Numerical simulation on wind-driven cross ventilation in square arrays of urban buildings with different opening positions

Effective wind-driven cross ventilation requires a well-designed opening, such as a window, to allow sufficient exchange between indoor and outdoor air, especially when the building is surrounded by other buildings. Using computational fluid dynamics, the present study investigated the effect of different opening positions on wind-driven ventilation in a building in an area with a packing density of 25%. The renormalizationgroup κ-ε turbulence model, a type of Reynolds-averaged Navier-Stokes (RANS) model, was used to characterize the airflow in cubical building blocks arranged in a square array. Nine different configurations of aligned cross openings and nine configurations with non-aligned outlet positions were tested. The ventilation rates obtained for the aligned cross openings showed that openings positioned at the uppermost of the windward and leeward façade provided highest ventilation rate. The ventilation rate was reduced by 75% when the openings were positioned at the bottom of the façade. As for the fixed inlet in the centre, the ventilation rate was 100% higher when the outlet is at the top of the leeward façade compared to the bottom of the façade. The outcomes of this study show that opening position is imperative in providing effective wind-driven cross ventilation in urban areas.