Abstract
Large-eddy simulation was implemented for airflow and thermal diffusion in an urban canyon. To evaluate the performance of the LES, the mean velocities, standard deviations of turbulent fluctuations and mean temperature estimated by the LES are compared with those obtained by wind-tunnel experiments. The results show that the LES can capture the flow and temperature within the canyon, and accurately represent the effect of the wall heating on flow within the canyon. Though the previous studies only focused on the vertical cross section, it is found that two axisymmetrical vortexes are formed in the horizontal cross section with a large clockwise vortex in vertical cross section irrespective of the wall heating conditions. The horizontal vortexes are enlarged by wall heating, and horizontal turbulent fluctuations are increased. Thus, the thermal environment within the canyon is affected not only by the vertical large vortex, but also by the horizontal turbulent flow.
