Buoyancy effects on the flows around flat and steep street canyons in simplified urban settings subject to a neutral approaching boundary layer: Wind tunnel PIV measurements

The present wind tunnel particle image velocimetry (PIV) measurements document flows around flat and steep street canyons subject to thermal conditions at different levels, ranging from the Richardson number of 0.31 2.07. A steepness ratio, that is, ratio windward leeward building heights, is proposed characterise geometrical influence surrounded by buildings non-uniform height. To study effects façades ground on surrounding flow, surfaces models between them are heated up maintained three temperatures induce buoyant strength. transition canyon flow typical rooftop shear-layer driven vortex plume type clearly revealed measurement results, which enhances air removal takes place roof-level two canyons. However, due canyons, rate a 2.52 approximately 50% with 1.53 in plume-driven case because downward flush along façade suppresses ascending plumes canyon. At pedestrian level, field jointly dominated interplay canyon-wide vortical rising ground. dynamics non-isothermal detail, implication has be considered urban morphology planning, as well simplified representations canopy models.