Scaling of building affected plume rise and dispersion in water channels and wind tunnels—Revisit of an old problem

Pournazeri, Sam; Princevac, Marko; Venkatram, Akula

doi:10.1016/j.jweia.2012.01.006

Cited by 24 publications

(13 citation statements)

References 49 publications

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“…Simulating flow and dispersion in such a laboratory facility requires utilizing correct scaling techniques. These scaling methods are explained in detail by Pournazeri et al (2012b) and will not be repeated here. …”

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confidence: 99%

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Sound wall barriers: Near roadway dispersion under neutrally stratified boundary layer

Pournazeri

Princevac

2015

Transportation Research Part D: Transport and Environment

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a b s t r a c tWith the passage of California Senate Bill 375, which motivates infill development near transit hubs, there is the potential to increase vehicle congestion in residential communities and increase in human exposure to toxic mobile source pollutants. Among all the mitigation strategies that protect near roadway residents from health-affecting vehicular emissions (e.g. separating sensitive receptors from high traffic roadways), this paper discusses the impact of sound wall barriers (SBs) in reducing the air pollution exposure of nearby residents. To date, there have been some studies done to understand the impact of these structures on dispersion of vehicular emissions; however, no definitive conclusion has been drawn yet. The main objective of this paper is to provide more information and details on flow and dispersion affected by barriers through a systematic laboratory simulation of plume dispersion using a water channel. Three sets of experiments were conducted: (1) plume visualizations, (2) plume concentration measurements, and (3) flow velocity measurements. Results from this study shows that the deployment of sound barriers induces a recirculating flow over the roadway which transports the surface released emissions to the upwind side of the roadway, and then shifts the plume upward through an induced updraft motion. Plume visualizations clearly demonstrate that the presence of SBs induce significant vertical mixing and updraft motion on the roadway which increases the initial plume dilution and plume height and consequently results in reduced downwind ground level concentrations. Although different SB configurations result in different localized flow patterns, the dispersion pattern does not change significantly after several SB heights downwind of the roadway.Ó 2015 Elsevier Ltd. All rights reserved. IntroductionNumerous epidemiological studies have shown that long-term exposure to outdoor air pollution increases the risk of respiratory diseases, birth defects, premature mortality, cardiovascular disease, and cancer (Dockery and Pope, 1994;Harrison et al., 1999;Wilhelm and Ritz, 2003;Peters et al., 2004;Jerrett et al., 2005;McConnell et al., 2006). Houston et al. (2006) showed that more than 24,000 childcare centers in California are within 200 m of highly trafficked roadways with more than 50,000 vehicles per day. A statistical analysis has shown that children diagnosed with asthma are more likely to live within 500 m of major roadways (Edwards et al., 1994).

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confidence: 99%

“…Details of scaling of flow and dispersion in the water channel are provided in Pournazeri et al (2012b).…”

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confidence: 99%

Sound wall barriers: Near roadway dispersion under neutrally stratified boundary layer

Pournazeri

Princevac

2015

Transportation Research Part D: Transport and Environment

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“…7e). This effect has also been studied by Oke (1987) who mentioned that the stagnation point occurs at approximately 2/3 the height of the building. The result from our flow measurements in Fig.…”

Section: Downstream Buildingsmentioning

confidence: 78%

“…The results from the plume-rise measurements discussed previously are also compared with the predictions from a new numerical plume-rise model (Pournazeri et al 2012). This model solves the plume-rise governing equations developed by Hoult et al (1969) modified to account for both vertical and horizontal wind-speed components, instead of only horizontal.…”

Section: Comparison With Numerical Plume-rise Modelmentioning

confidence: 99%

“…However, in cases with relatively high turbulent intensities, ambient turbulence can reduce the plume rise at large distances. In Pournazeri et al (2012), this model is evaluated for the case where only the DPG building is present. In this study, using the flow measurements shown in the previous section, the plume effective height (h e = h p + H s ) associated with the DPG model under different surrounding building geometries has been predicted and compared with the plume effective height measured in the laboratory (Fig.…”

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Rise of Buoyant Emissions from Low-Level Sources in the Presence of Upstream and Downstream Obstacles

Pournazeri

Princevac

Venkatram

2012

Boundary-Layer Meteorol

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Field and laboratory studies have been conducted to investigate the effect of surrounding buildings on the plume rise from low-level buoyant sources, such as distributed power generators. The field experiments were conducted in Palm Springs, California, USA in November 2010 and plume rise from a 9.3 m stack was measured. In addition to the field study, a laboratory study was conducted in a water channel to investigate the effects of surrounding buildings on plume rise under relatively high wind-speed conditions. Different building geometries and source conditions were tested. The experiments revealed that plume rise from low-level buoyant sources is highly affected by the complex flows induced by buildings stationed upstream and downstream of the source. The laboratory results were compared with predictions from a newly developed numerical plume-rise model. Using the flow measurements associated with each building configuration, the numerical model accurately predicted plume rise from low-level buoyant sources that are influenced by buildings. This numerical plume rise model can be used as a part of a computational fluid dynamics model.

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Pollutant dispersion by tall buildings: laboratory experiments and Large-Eddy Simulation

et al. 2022

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Pollutant dispersion by a tall-building cluster within a low-rise neighbourhood of Beijing is investigated using both full-scale Large-Eddy Simulation and water flume experiments at 1:2400 model-to-full scale with Particle Image Velocimetry and Planar Laser-Induced Fluorescence. The Large-Eddy Simulation and flume results of this realistic test case agree remarkably well despite differences in the inflow conditions and scale. Tall buildings have strong influence on the local flow and the development of the rooftop shear layer which dominates vertical momentum and scalar fluxes. Additional measurements using tall-buildings-only models at both 1:2400 and 1:4800 scales indicates the rooftop shear layer is insensitive to the scale. The relatively thicker incoming boundary layer affects the Reynolds stresses, the relative size of the pollutant source affects the concentration statistics and the relative laser-sheet thickness affects the spatially averaged results of the measured flow field. Low-rise buildings around the tall building cluster cause minor but non-negligible offsets in the peak magnitude and vertical location, and have a similar influence on the velocity and concentration statistics as the scale choice. These observations are generally applicable to pollutant dispersion of realistic tall building clusters in cities. The consistency between simulations and water tunnel experiments indicates the suitability of both methodologies. Graphical abstract

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Scaling of building affected plume rise and dispersion in water channels and wind tunnels—Revisit of an old problem

Cited by 24 publications

References 49 publications

Sound wall barriers: Near roadway dispersion under neutrally stratified boundary layer

Sound wall barriers: Near roadway dispersion under neutrally stratified boundary layer

Rise of Buoyant Emissions from Low-Level Sources in the Presence of Upstream and Downstream Obstacles

Pollutant dispersion by tall buildings: laboratory experiments and Large-Eddy Simulation

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