Large eddy simulation of flow around covered roadway: comparison between 2D and 3D simulation

摘要

The turbulent flow around covered roadway resembles an urban setting where pollutant concentrations exceed ambient air quality standards and exposure to large number of people exists as well. In this paper, the turbulent flow inside and around covered roadway is simulated using large eddy simulation (LES) in order to asses the capability of 2D simulation compared to 3D computation. The simulations, which are done under similar conditions, showed that the 2D calculations could not resolve the flow field well inside the covered roadway and hardly a flow filed can be noticed inside the covered roadway. Consequently, other dependent parameters such as pollutant transport and ventilation efficiency indices will significantly be impacted. This descent in the flow filed, and consequently its dependent parameters, is due to the fact that vortex stretching mechanism affects greatly the energy cascade process and turbulence transport.