A wind tunnel study of the effect of downstream buildings on near-field pollutant dispersion

Abstract

The effect of near-field pollutant dispersion characteristics for the case of downstream buildings in the urban environment has been presented in this paper. Wind tunnel data were obtained for nine different building configurations, three exhaust momentum ratios (M) and three stack heights (hs), for wind azimuth of 0 o . Tracer gas concentrations were measured on the roof, windward and leeward walls of each building.When a tall downstream building was located within the recirculation length of the emitting building, higher rooftop concentration was measured on the emitting building than for the isolated building case. Results also show that the height and across-wind dimension of the downstream building, as well as the spacing between buildings are critical parameters in assessing plume dilution. ASHRAE 2007 and ASHRAE 2011, which apply Gaussian-based models for the evaluation of dilution, are unable to model the effect of adjacent buildings; the former yielded lower dilution for all cases examined whilst the latter was found to be suitable only for specific limited cases. Design guidelines for the placement of stack and intakes to avoid or minimize plume re-ingestion are proposed.

Ten questions concerning modeling of near-field pollutant dispersion in the built environment

“…They found that ASHRAE 2007 predictions were overly conservative for the isolated building, while the ASHRAE 2011 estimates compared better with experimental data in some cases. However, as suggested by [117,118], neither ASHRAE model is capable of modeling the effect of adjacent buildings; further investigation of the formulations underlying these models is required. There is no change in the Gaussian plume models between 2011 and 2015 versions.…”

“…[109][110][111][112][113], configuration of adjacent buildings, e.g. [114][115][116][117][118][119], and roof geometry, e.g.…”

On the use of numerical modelling for near-field pollutant dispersion in urban environments − A review

“…A number of different approaches have been widely used for studying pollutant dispersion around buildings in urban environments: full-scale field measurements (Drivas and Shair, 1974;Ogawa and Oikawa, 1982;Jones and Griffiths, 1984;Wilson and Lamb, 1994;Higson et al, 1996;Mavroidis et al, 1999Mavroidis et al, , 2003Stathopoulos et al, 2004Stathopoulos et al, , 2008Yassin et al, 2005;Santos et al, 2009;Finn et al, 2010;Baldauf et al, 2013), physical modelling (Li and Meroney, 1983;Poreh and Cermak, 1990;Higson et al, 1994;Wu and Meroney, 1995;Sini et al, 1996;Delaunay et al, 1997;Stathopoulos et al, 1999;White, 2003;Chang and Meroney, 2003;Aubrun and Leitl, 2004;Gomes et al, 2007;Nakiboglu et al, 2009;Liu et al, 2010;Pournazeri et al, 2012;Carpentieri et al, 2012;Yassin, 2013;Meroney et al, 2015), semi-empirical methods (Saathoff and Stathopoulos, 1997;Ratcliff and Sandru, 1999;Stathopoulos et al, 2002;ASHRAE, 2007;Hajra et al, 2010Hajra et al, , 2013ASHRAE, 2011;Chavez et al, 2011;Hajra and Stathopoulos, 2012;…”

A simplified benchmark of ultrafine particle dispersion in idealized urban street canyons: A wind tunnel study

“…A C C E P T E D ACCEPTED MANUSCRIPT 3 determining intense exposure of the population to such particles [18,36]. Thus, in order to properly carry out aerosol exposure assessments in urban street canyons, it is crucial to evaluate both the ultrafine particle production rate and the corresponding dispersion.…”