Evaluation of the Wind Environment around Multiple Urban Canyons Using Numerical Modeling

Abstract

This study aimed to evaluate the wind environment in step-up and step-down urban canyons through a computational numerical experiment using the computational fluid dynamics (CFD) model. Spatial structural conditions were considered according to the location of high-rise buildings, and the changing wind patterns inside canyons were compared and analyzed by varying the building heights. Under the step-up to step-down condition, wind velocity inside the canyon weakened, a vertical vortex formed, and vertical air flow separated; additionally, in shallow and deep canyons, wind velocity and detailed flow differed slightly according to each additional condition. For the step-down to step-up condition, the building located in the center appeared to be isolated, and a general wind environment phenomenon consistent with the step-up and step-down structures was observed. However, depending on the isolated area, an additional roof-top canyon was formed, and the wind field in the canyon was found to affect the wind velocity and detailed flow in other canyons. The wind velocity components of the inflow and outflow winds into the canyon differed based on the step-up to step-down or step-down to step-up conditions, and according to the conditions in the first and second canyons. Furthermore, the vertical wind velocity components were greatly affected by the step-up and step-down structures. Accordingly, the height and structural location of the building could affect various phenomena, such as the separation of vortices and air currents inside the canyon, and a variable wind environment was formed according to a series of conditions for the building.

Large-Eddy Simulation of Airflow and Pollutant Dispersion in a Model Street Canyon Intersection of Dhaka City

“…Therefore, LES is a better candidate in this regard. The flow through the street canyon is determined by the aspect ratio (AR), which is the ratio of the building height (h) and the street width (w) [14]. Several works were found in the literature where different flow patterns, geometries, simulation techniques, and AR were reported for the benefit of each project.…”

“…The review by Zhang et al [16] is another good source of information for comparing different methods. Recently, Son et al [14] evaluated wind environments around multiple urban canyons through the k − turbulence termination method that was inspired by the renormalization group (RNG) theory for turbulence parametrization as part of an initial assessment with scopes of further exploration in terms of weather or other coefficients correlating to the wind environment.…”