Turbulent flow over street canyons with balconies

Flow over a single street canyon with balconies located along the leeward and windward walls is studied using large-eddy simulation. The effect of different balcony configurations on the mean flow and turbulence statistics is assessed for height-to-width canyon aspect ratios of AR = 0.25, 0.5, 1.0 and a mean flow perpendicular to the canyon axis. For sufficiently small balconies, the flow continues to be well-described by the canyon aspect ratio; for more closely packed balconies, the applicability of alternative parameters, such as the effective aspect ratio for the interior (AR_e) and the balcony aspect ratio for the balcony regions (AR_b), is investigated. Over a wide range of balcony configurations, the mean flow, and to a lesser extent the turbulent kinetic energy (TKE), are described by AR_e and the normalised balcony separation distance (s^′). It is argued that this is a consequence of the flow within the balconies being driven by a canyon-like flow within the interior. © 2025 Elsevier B.V.