Turbulent flow over street canyons with balconies

Abstract

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 $\mathrm{AR}=\mathrm{0.25,0.5,1.0}$ 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 (${\mathrm{AR}}_e$) and the balcony aspect ratio for the balcony regions (${\mathrm{AR}}_b$), 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 ${\mathrm{AR}}_e$ and the normalised balcony separation distance ($s^{\prime }$). It is argued that this is a consequence of the flow within the balconies being driven by a canyon-like flow within the interior.