Title: Dispersion of buoyant emissions from low level sources in urban areas: water channel modelling

Authors: Sam Pournazeri; Nico Schulte; Si Tan; Marko Princevac; Akula Venkatram

Addresses: Department of Mechanical Engineering, University of California Riverside, Riverside, CA 92521, USA ' Department of Mechanical Engineering, University of California Riverside, Riverside, CA 92521, USA ' Department of Mechanical Engineering, University of California Riverside, Riverside, CA 92521, USA ' Department of Mechanical Engineering, University of California Riverside, Bourns Hall A359, Riverside, CA 92521, USA ' Department of Mechanical Engineering, University of California Riverside, Bourns Hall A343, Riverside, CA 92521, USA

Abstract: A laboratory study was done to investigate dispersion of buoyant emissions from near surface sources in urban areas. Ground level concentrations under different surrounding building geometries were measured using a newly developed system based on laser induced fluorescence. In the presence of upstream buildings AERMOD (AMS/U.S. EPA regulatory dispersion model) is unable to explain concentrations close to the source. Plume visualisations and velocity measurements show that upstream buildings induce low velocity and a highly turbulent region near the stack, which increases the plume rise and induces rapid vertical mixing. Also, the urban canopy imposes a length scale on the horizontal turbulence, causing the plume to spread laterally with the square root of distance (∼x^1/2) rather than linearly as occurs in open terrain. A Gaussian-based dispersion model which accounts for these effects performs substantially better in predicting ground level concentrations associated with buoyant emissions from distributed power generators in urban areas.

Keywords: AERMOD; air quality; air pollution; buoyant emissions; Gaussian based dispersion modelling; distributed power generators; urban areas; water channel modelling; near surface sources; plume visualisation; velocity measurement; urban canopy; horizontal turbulence.

DOI: 10.1504/IJEP.2013.058460

International Journal of Environment and Pollution, 2013 Vol.52 No.3/4, pp.119 - 140

Received: 11 Jan 2013
Accepted: 22 Oct 2013
Published online: 28 Feb 2014 *

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