Study of Wind Flow Patterns and Heavy Gas Pollutants Dispersion Under Isolated Building Terrain

Experiment and simulation were used to study the dispersion characteristics of heavy gas pollutants represented by carbon dioxide in isolated building terrain. Wind tunnel experiment and laser particle tracing technology were used to characterize the features of wind flow and the dispersion of pollutants. The influences of the distance from the building to the release source and the size of the building were explored. The results show that the height of the building has a significant effect on the wind speed and turbulence intensity on the windward and leeward sides of the building, and the side width of the building has a slightly weaker effect. The area of the recirculation region on the leeward side of the building and the barrier effect on pollutants are dominated by the windward area of the building, that is, the larger the windward area, the larger the recirculation region and the lower the concentration of pollutants on the leeward side. At the same time, the decline rate of pollutants on the windward side increases with the increase of the windward area. The heavy gas pollutants tend to spread around the building side with the wind flow, unless the distance from the building to the source is too short or the building is too long. And when the pollutants climb to the top of the building, the dispersion of them will slows down as the width of the building side increases. The RNG k-ε model was used for simulation to provide a visible result for wind flow, and its applicability and accuracy were verified.

Fenômeno de meandro do vento e a função de autocorrelação calculada com base na concentração de poluentes simulada pelo modelo transiente 3D-GILTT

The aim of this work is to present a pollutants dispersion transient model in low wind conditions to simulate the behavior of the pollutants plume in the atmosphere, considering in the model the u e v horizontal wind components simulated by the LES-PALM model. The dispersion model is based in the advection-diffusion equation and represent by this methodology the wind meandering phenomenon. The Generalized Integral Laplace Transform Technique in three dimensions (3D- GILTT) solves the transient advection-diffusion equation. The data utilized to initialize the simulations are data of the low wind INEL (Idaho National Engineering Laboratory) experiment accomplished in EUA. The results show that the dispersion model reproduces the wind meandering phenomenon, in other words, the autocorrelation function of the concentration simulated over an hour presents the negative lobule, similarly to observed lobules in the u and v wind components. Therefore, the model simulates the pollutants plume in a satisfactory way and can be used to air quality regulatory applications in low wind and wind meandering conditions.

Concentration modeling of hydrocarbons, carbon monoxide, carbon dioxide and nitrogen oxides emitted from cigarette consumption in atmosphere of Isfahan, Iran

Introduction: Although many studies on Isfahan’s air pollution have been done, there is no report about the effects of cigarette consumption in Isfahan. The aims of this study were (a) to find the amount of nitrogen oxides, hydrocarbons, carbon monoxide and carbon dioxide emitted by cigarette consumption in Isfahan; and (b) to model the distribution of such pollutants in Isfahan’s atmosphere. Materials and methods: Based on the literature, it is assumed that 15% of Isfahan’s people consume cigarettes and each smoker on average smokes 1,147 cigarettes per year. Based on these assumptions, the 249,000 smokers living in Isfahan consume 285,000,000 cigarettes per year. The amount of pollutant emissions was calculated by existing emission factors for cigarette consumption. Finally, the distribution of the emitted pollutants from cigarette consumption in Isfahan’s atmosphere was modeled using AERMOD. Results: The results illustrated that each year, 2.85 kg nitrogen oxides, 2.85 kg hydrocarbons, 37.05 kg carbon monoxide and 142.5 kg carbon dioxide are emitted into Isfahan’s atmosphere from residents’ smoking. The modeling of pollutants’ dispersion in Isfahan’s atmosphere showed that only some of these pollutants result from cigarette consumption. Conclusion: This study demonstrated that the amount of pollutants emitted by cigarette consumption was negligible compared to the other pollutant sources in Isfahan.