Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nakayama, Hiromasa; Jurcakova, K.*; Nagai, Haruyasu
Journal of Nuclear Science and Technology, 50(5), p.503 - 519, 2013/05
Times Cited Count：15 Percentile：74.42(Nuclear Science & Technology)There is a potential problem that hazardous materials are accidentally or intentionally released within populated urban areas. In this study, we perform LESs of plume dispersion in idealized urban canopies where the surface geometries are represented by regularly arrayed obstacle arrays with various obstacle densities. In this paper, we examine the basic performance of the LES model by comparing to wind tunnel experiments.
Nakayama, Hiromasa; Jurcakova, K.*; Nagai, Haruyasu
Advances in Science & Research (Internet), 10, p.33 - 41, 2013/02
Times Cited Count：11 Percentile：98.37(Multidisciplinary Sciences)There is a potential problem that hazardous and flammable materials are accidentally or intentionally released within urban areas. Our objective is to compare our LES results for distribution patterns of mean and fluctuating concentrations in various actual urban areas with the existing LES and experimental results for those in regularly arrayed obstacles, and investigate the influence of actual urban surface geometries on the characteristics of mean and fluctuating concentrations.
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; Jurcakova, K.*; Nagai, Haruyasu
Advances in Science & Research (Internet), 6, p.79 - 86, 2011/04
Times Cited Count：0 Percentile：1.11(Multidisciplinary Sciences)In this study, the cubic building arrays with roughness density of 0.16, 0.25 and 0.33 are set up. These surface geometries consist of 20
6, 257 and 289 arrays in streamwise and spanwise directions, respectively. Three cases of plume source located at the ground surface behind the building in the 6th, 7th and 8th row of the building array are tested. As a result, we can capture the dispersion process of a plume and the spatial distribution of mean and fluctuating concentrations depending on roughness density.
