A three-dimensional computational fluid dynamics model with the renormalization group k–e turbulence scheme is developed. The model developed is used to investigate the effects of ambient wind direction on flow and dispersion around a group of buildings. According to the ambient wind direction, three flow patterns are identified in a view of the characteristics of the mean flow circulation generated in street canyons. In the first flow pattern, a portal vortex generated behind the east wall of the upwind building is symmetric about the center of the street canyon. In the second flow pattern, a portal vortex is also generated behind the east wall of the upwind building, but its horizontal axis is not perpendicular to the ambient wind direction. In the third flow pattern, the footprints of a portal vortex are located behind both the east and north walls of the upwind building. When the incident wind angle is 45°, flow is diagonally symmetric behind the upwind building. As the incident wind angle increases, pollutant escape from the street canyons decreases. Except for the case where the ambient wind direction is perpendicular to the buildings, pollutants are trapped in the portal vortex, thus exhibiting high concentration there.

A numerical study of the effects of ambient wind direction on flow and dispersion in urban street canyons using the RNG k-ε turbulence model

Air quality affected by trees in real street canyons: The case of Marylebone neighbourhood in central London

Enhancing urban ventilation performance through the development of precinct ventilation zones: A case study based on the Greater Sydney, Australia

The impacts of building height variations and building packing densities on flow adjustment and city breathability in idealized urban models

https://pure.tue.nl/ws/files/80916680/1_s2.0_S0360132317304687_main.pdf

Xieyuan Chen

Papers

City breathability in medium density urban-like geometries evaluated through the pollutant transport rate and the net escape velocity

The influence of aspect ratios and wall heating conditions on flow and passive pollutant exposure in 2D typical street canyons