Experimental study of single-sided ventilation through a roof opening using isolated generic models

• Extensive wind tunnel experiments were conducted on SSV via a roof opening. • A benchmark dataset with generic models was created with varied configurations. • Links were built between free-end flow separation and ventilation mechanisms. • Flow pattern above a high-plan aspect ratio cuboid was studied across yaw angles. • Marked enhancement of ventilation was observed with presence of conical vortex. Previous studies have rarely addressed single-sided ventilation driven by the external flow over the roof, which exhibits strong potential owing to its highly turbulent nature and strong suction associated with leading-edge flow separation. In this study, wind tunnel experiments on single-sided ventilation through a roof opening were conducted using two isolated generic models: a cylinder and a rectangular prism, each with a set of replaceable openings. Both models were tested either flush- or floor-mounted. Two inflow conditions, each with three free-stream velocities, were considered. For both models mounted beneath the floor, the nondimensional ventilation rates ( Q* ) are comparable to values reported in the literature; for the prism, a slight increase in Q* with orientation suggests the development of a mixing layer along the streamwise extent of the floor-level opening. In the floor-mounted configuration, body-induced flow disturbances tend to enhance ventilation. Three primary governing rooftop flow regimes are identified—recirculation zone, flow reattachment, and conical vortex—whose relative dominance over the opening depends on inflow turbulence, wind incidence angle, and model configuration. When the opening lies entirely within the recirculation zone, Q* is proportional to the normalized local fluctuation intensity, with a coefficient of about 0.16. For certain yaw angles, the marked increase in Q* strongly correlates with the presence of a conical vortex over the prism model roof, which features strong suction and intense fluctuations. Direct advection through the opening could occur with a favorable opening size and location, allowing deep penetration of the reattaching shear layer.