scholarly journals Large-eddy simulation of plume dispersion within regular arrays of cubic buildings

2011 ◽  
Vol 6 (1) ◽  
pp. 79-86
Author(s):  
H. Nakayama ◽  
K. Jurcakova ◽  
H. Nagai
Keyword(s):  
Large Eddy Simulation ◽  
Urban Areas ◽  
Health Hazard ◽  
Critical Threshold ◽  
Plume Dispersion ◽  
Toxic Substances ◽  
High Concentration ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Regular Arrays

Abstract. There is a potential problem that hazardous and flammable materials are accidentally or intentionally released within populated urban areas. For the assessment of human health hazard from toxic substances, the existence of high concentration peaks in a plume should be considered. For the safety analysis of flammable gas, certain critical threshold levels should be evaluated. Therefore, in such a situation, not only average levels but also instantaneous magnitudes of concentration should be accurately predicted. In this study, we perform Large-Eddy Simulation (LES) of plume dispersion within regular arrays of cubic buildings with large obstacle densities and investigate the influence of the building arrangement on the characteristics of mean and fluctuating concentrations.

Large-eddy Simulation of Plume Dispersion over Hypothetical Urban Areas

2020 ◽  
Author(s):  
Zhangquan Wu ◽  
Chun-Ho Liu
Keyword(s):  
Nitric Oxide ◽  
Air Quality ◽  
Large Eddy Simulation ◽  
Urban Areas ◽  
Turbulent Dispersion ◽  
Anthropogenic Sources ◽  
Plume Dispersion ◽  
Street Canyons ◽  
Eddy Simulation ◽  
Large Eddy

<p>More than 80% of people living in urban areas that exposed to air quality levels that exceed WHO guideline limits both indoors and outdoors. Road transport has been found to be one of major anthropogenic sources of aerosol particles and many gaseous pollutants in urban areas. Dispersion of pollutants emitted from vehicles over urban areas largely affects pedestrian-level air quality. A good understanding of pollutant transport, mixing process and removal mechanism is crucial to effectuate air quality management. In this study, turbulent dispersion of reactive pollutants in the atmospheric boundary layer (ABL) over hypothetical urban area in the form of an array of idealised street canyons is investigated using large-eddy simulation (LES). The irreversible ozone O3 titration oxidizes nitric oxide NO to nitrogen dioxide NO2, representing the typical anthropogenic air pollution chemistry. Nitric oxide (NO) is emitted from the ground level of the first street canyon into the urban ABL doped with ozone (O3). From the LES results, negative vertical NO flux is found at the roof level of the street canyons.  By looking into the different plume behavior and vertical flux between the inert pollutant and chemically reactive pollutant, a fundamental understanding of exchange processes of anthropogenic chemicals between an urban surface and the atmosphere is developed. </p>

Large eddy simulation of wind field and plume dispersion in building array

2008 ◽  
Vol 42 (6) ◽  
pp. 1083-1097 ◽  
Author(s):  
R.F. Shi ◽  
G.X. Cui ◽  
Z.S. Wang ◽  
C.X. Xu ◽  
Z.S. Zhang
Keyword(s):  
Large Eddy Simulation ◽  
Wind Field ◽  
Plume Dispersion ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Building Array

scholarly journals Large-eddy simulation of plume dispersion under various thermally stratified boundary layers

2014 ◽  
Vol 11 (1) ◽  
pp. 75-81 ◽  
Author(s):  
H. Nakayama ◽  
T. Takemi ◽  
H. Nagai
Keyword(s):  
Large Eddy Simulation ◽  
Boundary Layers ◽  
Atmospheric Stability ◽  
Spanwise Direction ◽  
Plume Dispersion ◽  
Convective Boundary ◽  
Gas Dispersion ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Les Model

Abstract. Contaminant gas dispersion in atmospheric boundary layer is of great concern to public health. For the accurate prediction of the dispersion problem, the present study numerically investigates the behavior of plume dispersion by taking into account the atmospheric stability which is classified into three types; neutral, stable, and convective boundary layers. We first proposed an efficient method to generate spatially-developing, thermally-stratified boundary layers and examined the usefulness of our approach by comparing to wind tunnel experimental data for various thermal boundary layers. The spreads of plume in the spanwise direction are quantitatively underestimated especially at large downwind distances from the point source, owing to the underestimation of turbulence intensities for the spanwise component; however, the dependence of the spanwise spreads to atmospheric stability is well represented in a qualitative sense. It was shown that the large-eddy simulation (LES) model provides physically reasonable results.

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