Numerical investigations of wind and thermal environment in 2D scaled street canyons with various aspect ratios and solar wall heatingShow others and affiliations
2021 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 190, article id 107525Article in journal (Refereed) Published
Abstract [en]
Optimizing urban ventilation is an effective way to improve urban air quality and thermal environment. For this purpose, under the validation of wind-tunnel experiments, flow regimes and micro thermal environment in typical reduced-canyon models with aspect ratios (AR) of 1.1, 2.4, 4 and 5.67 were investigated by CFD simulations using periodic boundary condition. ANSYS Fluent 15.0 with a solar ray tracing model and radiation model was performed to numerically study turbulence characteristics with wind-driven force and solar-heating conditions. Results revealed that, with wind-driven condition, a clockwise vortex existed in normal and deep street canyon (AR = 1.1 and 2.4) while two counter-rotating vortices appeared in extremely deep canyon (AR = 4 and 5.67). Moreover, different turbulence structures and air temperature distribution existed in canyons with different solar-heating conditions. When the leeward wall or ground was heated, the pedestrian-level velocity increased and street ventilation was strengthened compared to wind-driven condition for all AR values. Particularly, the single main vortex was strengthened (AR = 1.1 and 2.4), and the two-vortex structure in extremely deep canyons (AR = 4 and 5.67) changed to single-vortex structure. When the windward wall was heated, the clockwise main vortex at AR = 1.1 and 2.4 was deformed, and a new sub vortex gradually appeared near street bottom. Furthermore, at AR = 4 and 5.67, windward solar heating destroyed the two-vortex structure and slightly improved pollutant dilution capacity. This work implied that extremely deep street design with weak pedestrian-level ventilation should be avoided. It also provides a meaningful reference for urban planning.
Place, publisher, year, edition, pages
Elsevier , 2021. Vol. 190, article id 107525
Keywords [en]
2D street canyon, Aspect ratio, Wind tunnel experiment, CFD simulation, Wind-driven, Solar heating condition
National Category
Civil Engineering Earth and Related Environmental Sciences Mechanical Engineering
Research subject
Sustainable Urban Development
Identifiers
URN: urn:nbn:se:hig:diva-34700DOI: 10.1016/j.buildenv.2020.107525ISI: 000613563600002Scopus ID: 2-s2.0-85098698984OAI: oai:DiVA.org:hig-34700DiVA, id: diva2:1516950
2021-01-132021-01-132025-01-31Bibliographically approved