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Comparing different VIT formulations on near-road dispersion of particulate and gaseous pollutants
Citation:
Hashad, K., B. Yang, V. Isakov, AND M. Zhang. Comparing different VIT formulations on near-road dispersion of particulate and gaseous pollutants. 2017 AAAR Annual Conference, Raleigh, NC, October 16 - 20, 2017.
Impact/Purpose:
Poster to be presented at the 36th AAAR Annual Conference to highlight research done under ACE task PEP-2.5 “Evaluation and development of tools and resources to design and quantify the use of green infrastructure in mitigating transportation and urban air quality”.
Description:
Traffic-related air pollution is associated with a range of health issues including respiratory and cardiovascular problems, birth defects, and cancer. Recent studies suggest that the presence of roadside barriers can potentially mitigate exposure to air pollution for those living and working close to major roads. As vehicle-induced turbulence (VIT) has a strong effect on the initial dispersion of pollutants, it would be challenging to explore the impact of roadside barriers without a proper understanding of VIT. Our study compares three different techniques to model VIT. The first method models VIT as a fixed volume source where turbulence is uniformly produced in the highway computational domain. The second method treats each highway lane as a forcing zone where an estimate for the drag force produced by vehicles in that lane would be imposed into the domain. The third method distributes the drag force of each vehicle into the domain using a Gaussian function such that computational grid points close to vehicles would experience a strong forcing as opposed to grid point further away. To evaluate the accuracy of each method, the simulation results are compared to experimental data obtained in an USEPA field study on a major highway in Las Vegas. The experimental data include extensive, collocated measurements of traffic, turbulence and air pollutant concentrations. The turbulent kinetic energy and pollutant concentration obtained from the simulations are compared with those of the field study. The impact of VIT on pollutant dispersion will also be explored for the different techniques.
