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Computational fluid dynamics modeling to assess the impact of roadside barriers on near-road air quality
Citation:
HAGLER, G., W. Tang, M. J. Freeman, D. HEIST, S. G. PERRY, AND A. F. VETTE. Computational fluid dynamics modeling to assess the impact of roadside barriers on near-road air quality. In Proceedings, Computational Wind Energy, Chapel Hill, NC, May 23 - 27, 2010. International Association for Wind Engineering (IAWE), Atsugi, Kanagawa, Japan, xxx, (2010).
Impact/Purpose:
symposium paper
Description:
Near-road air quality is an issue of emerging concern, with field studies consistently showing elevated air pollutant concentrations adjacent to major roads, usually decreasing to background levels within several hundred meters. Roadside barriers, both vegetative and structural, are expected to alter the dispersion patterns of traffic-related emissions and the resulting ambient air pollutant concentrations. In order to understand the influence of roadside barriers on near-road air quality, an idealized computational fluid dynamics (CFD) model of a roadway was developed and simulated using FLUENT. The CFD turbulence model selection and surface roughness parameters were based on comparison with previous wind tunnel experiments. The model includes a six-lane highway and a single-lane access road parallel to the highway which are separated by a solid noise wall. The noise wall is finite in length, allowing the impact of barrier edges to be observed. Downwind normalized air pollutant concentrations (Chi) and turbulent kinetic energy (TKE) are compared for barrier versus no-barrier road segments. The presence of a roadside barrier was observed to significantly impact the horizontal and vertical profiles of Chi and TKE under neutral stability conditions. In addition, the evaluation of barrier-impacted emissions dispersion under oblique wind directions is discussed.
