Large eddy simulation study of thermal effects on street canyon flow patterns
Faculty of Physics, University of Isfahan, 81746-73441, Isfahan, Iran
Accepted: 8 March 2022
Published online: 22 March 2022
In this paper, Turbulent flow patterns inside and above a street canyon with an aspect ratio of 1 according to different thermal conditions are simulated using a large eddy simulation (LES) model. To investigate heat flux and temperature stratification effects on flow patterns, six simulation cases performed, including heat fluxes and thermal stratification. In the case with no heat flux and no thermal stratification (neutral condition), a primary vortex appears at the center of the street canyon. Introducing heat flux at upwind building-wall and bottom-street surface reinforces the primary vortex. However, heating of the downwind wall creates a secondary vortex close to the heated surface and the primary vortex is weakened and shrunk. Stable thermal stratification inside the street canyon can eliminate the primary vortex and replaces it with small eddies, while the primary vortex persists in the unstable thermal stratification condition. Heating the bottom surface of the street causes a large horizontal temperature gradient across the width of the street canyon. In contrast, where the walls are heated, it confined to the vicinity of the heated building wall at pedestrian level. The results imply that heat forcing can intensify the turbulence and improves air ventilation inside the street canyon.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2022