Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nakayama, Hiromasa; Jurcakova, K.*; Nagai, Haruyasu
Proceedings of International Workshop on Physical Modelling of Flow and Dispersion Phenomena (PHYSMOD 2011) (CD-ROM), 8 Pages, 2011/08
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.
Nakayama, Hiromasa; Leitl, B.*; Nagai, Haruyasu; Harms, F.*
Proceedings of International Workshop on Physical Modelling of Flow and Dispersion Phenomena (PHYSMOD 2011) (CD-ROM), 8 Pages, 2011/08
An accurate analysis of atmospheric dispersion is important for emergency responses against accidental and intentional releases of hazardous and radioactive materials within populated urban areas. In this study, we evaluate the Large-Eddy Simulation (LES) model performance in comparison with the experimental datasets from the wind tunnel simulations of turbulent flow and plume dispersion in Oklahoma City. First, comparing with the experiments of approach flow, the turbulence characteristics of LES approach flow are found to be good agreement with 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 wind velocity and dispersion fields in the study site of Oklahoma City, it is found that the LES data are in good agreement with the experimental data.