LES of flow and plume dispersion within and over various obstacle arrays

Nakayama, Hiromasa   ; Jurcakova, K.*; Nagai, Haruyasu  

There is a potential problem that hazardous materials are intentionally released within populated urban areas. In this study, we perform Large-Eddy Simulation (LES) of plume dispersion within regular arrays of cubic buildings with various obstacle densities and investigate the influence of the building arrangement on the characteristics of mean and fluctuating concentrations. First, comparing with the experiments of approach flow, the turbulence characteristics of LES approach flow are found to be similar to those of the experiment. From this result, LES approach flow corresponding to a neutral atmospheric boundary layer is considered to be obtained. Next, comparing with the experimental results of concentrations in each case, the spanwise profiles of mean and r.m.s. concentrations are generally similar in the magnitude to the experimental data. Therefore, it is considered that our LES model for plume dispersion within various obstacle arrays gives satisfactory results.