Wind velocity and temperature fields under different surface heating conditions in a street canyon in wind tunnel experiments

Air velocity and temperature fields in urban street canyons depend mainly on the wind velocity at the rooftop level, the exposure of heated surfaces, and the canyon's aspect ratio (ratio of building height to street width). However, available experimental data for different surface heating conditions are limited. This study used particle image velocimetry to investigate the effects of four different surface heating conditions and three different aspect ratios on flow and temperature fields in wind tunnel experiments. In experiments when either the leeward or windward wall was heated, the largest heat load at all aspect ratios was near the midpoint of the scale model height, which means that the area at the half-height level of the canyon could provide benefits in reducing the heat load. In experiments when the ground was heated, heat tended to accumulate in different corners of the canyon wall at different aspect ratios in response to changes in the position of the vortex. This study improves understanding of how the extent of heated surfaces in street canyons influences the flow field and temperature distribution, expands the body of experimental data under various thermal conditions in wind tunnel experiments, and may supplement previous studies and validate relevant simulations. •PIV was used to obtain spatial structure of flow field.•The effects of different aspect ratio and surface heating conditions were investigated under different inflow velocity.•In facade heating conditions, the largest heat load at all aspect ratios was near the midpoint of the scale model height.•In ground heating conditions, heat tended to accumulate in different corners of the canyon wall at different aspect ratios.