Comparison of Wind-tunnel and Water-channel Simulations of Plume Dispersion through a Large Array of Obstacles with a Scaled Field Experiment

Yee, Eugene; Gailis, Ralph; Hill, Alexander; Hilderman, Trevor; Kiel, Darwin

doi:10.1007/s10546-006-9084-2

Cited by 55 publications

(44 citation statements)

References 25 publications

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“…For example, Yee and Biltoft (2004) describe a series of tracer experiments studying the statistical properties of concentration fluctuations (e.g., concentration variance, concentration probability density function, various concentration time and length scales of dominant plume motions) in a plume dispersing through a large array of building-like obstacles (an experiment referred to as the Mock Urban Setting Trial, or MUST). Gailis and Hill (2006) report a wide range of concentration statistics and other quantitative descriptors of plume behaviour for tracer dispersion in a wind-tunnel boundary-layer simulation of the MUST experiment. Yee et al (2006) provided detailed comparisons of concentration statistics in a plume dispersing through the MUST obstacle array at three different scales; namely, at fullscale in a field experiment, at 1:50 scale in a wind-tunnel simulation, and at 1:205 scale in a water-channel simulation.…”

Section: Introductionmentioning

confidence: 99%

“…Gailis and Hill (2006) report a wide range of concentration statistics and other quantitative descriptors of plume behaviour for tracer dispersion in a wind-tunnel boundary-layer simulation of the MUST experiment. Yee et al (2006) provided detailed comparisons of concentration statistics in a plume dispersing through the MUST obstacle array at three different scales; namely, at fullscale in a field experiment, at 1:50 scale in a wind-tunnel simulation, and at 1:205 scale in a water-channel simulation. Finally, Klein et al (2008) analyzed and compared concentration fluctuation measurements from the Joint Urban 2003 full-scale and wind-tunnel experiments.…”

Section: Introductionmentioning

confidence: 99%

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Probabilistic Model for Concentration Fluctuations in Compact-Source Plumes in an Urban Environment

Yee

Wang²,

Lien

2009

Boundary-Layer Meteorol

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A comprehensive model for the prediction of concentration fluctuations in plumes dispersing in the complex and highly disturbed wind flows in an urban environment is formulated. The mean flow and turbulence fields in the urban area are obtained using a Reynolds-averaged Navier-Stokes (RANS) flow model, while the standard k-turbulence model (k is the turbulence kinetic energy and is the viscous dissipation rate) is used to close the model. The RANS model provides a specification of the velocity statistics of the highly disturbed wind flow in the urban area, required for the solution of the transport equations for the mean concentrationc and concentration variance c 2 (both of which are formulated in the Eulerian framework). A physically-based formulation for the scalar dissipation time scale t d , required for the closure of the transport equation for c 2 , is presented. This formulation relates t d to an inner time scale corresponding to "internal" concentration fluctuation associated with relative dispersion, rather than an outer time scale associated with the entire portion of the fluctuation spectrum. The two lowest-order moments of concentration (c and c 2 ) are used to determine the parameters of a pre-chosen functional form for the concentration probability density function (clipped-gamma distribution). Results of detailed comparisons between a water-channel experiment of flow and dispersion in an idealized obstacle array and the model predictions for mean flow, turbulence kinetic energy, mean concentration, concentration variance, and concentration probability density function are presented.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probabilistic Model for Concentration Fluctuations in Compact-Source Plumes in an Urban Environment

Yee

Wang²,

Lien

2009

Boundary-Layer Meteorol

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“…Vertical profiles of standard deviation of horizontal and vertical velocities are maintained constant with a slight peak at 2.5 cm from the ground. The reference Reynolds number, based on the free stream velocity (v 1 ) and characteristics length scale, H Ã b (length scale based on the obstacle frontal area; H Ã b ¼ ðWHÞ 1=2 ) was Re = 12,600, which is sufficient to satisfy Reynolds number independency criteria of Re % 4000 (Halitsky, 1968;Fackrell and Pearce, 1981;Snyder, 1981;Yee et al, 2006). Although, such high Reynolds number satisfies the conditions to simulate real world atmospheric dispersion in the water channels, it needs to be noted that due to the nature of laboratory flow simulation systems, flows in water channels are more coherent than real atmosphere.…”

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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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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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“…In the past several decades, numerous studies have been conducted to address potential factors that could affect the dispersion of pollutants in urban areas. Wind tunnel (Macdonald et al, 1998a;Simoëns and Wallace, 2008) and water channel simulations (Yee et al, 2006) have revealed the modifications of flow, turbulence, and dispersion characteristics caused by the obstacles of various configurations and aspect ratios. The ambient wind direction relative to the street axis (Eliasson et al, 2006) could determine the mean wind profiles and recirculation flow within street canyons, which 482 could affect the distribution of pollution concentration (Baik and Kim, 1999).…”

Section: Introductionmentioning

confidence: 99%

Investigation of roadside fine particulate matter concentration surrounding major arterials in five Southern Californian cities

Pan

Bartolome

Gutierrez

et al. 2013

Journal of the Air & Waste Management Association

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The built environment surrounding arterials affects the dispersion of vehicular emissions in urban areas, modifying the potential risks to public health. In order to study the influence of urban morphometry on flow and dispersion of vehicular fine particulate matter emissions, in the summer of 2008 field measurements were performed in major arterials located in five Southern Californian cities with different building geometries. In each city, local mean wind, turbulence, virtual temperature, roadside DustTrak Fine Particles (DTFP) concentration, and traffic flow data were collected in 2-hr measurement periods during morning and evening rush hours and lighter midday traffic, over a period of 3 days. The calculated Monin-Obukhov length, L, suggests that near-neutral and slightly unstable conditions were present at both street and roof levels. The nondimensional forms of turbulent wind and temperature fluctuations show that the data at street level within the urban canopy can be represented using the Monin-Obukhov similarity theory. Generalized additive models were applied to analyze the impact of meteorological and traffic-related variables on fine particle concentrations at street level. Compared to other variables, urban-scale background concentrations were the most important variables in all five models. The results confirmed that turbulent mixing in urban areas dominated the variation of roadside particle concentrations regardless of urban geometry. The distance from the local sites to the nearby monitoring stations affected model performance when urban-scale concentrations were used to predict middle-scale concentrations by generalized additive models (GAMs). A radius of influence for background concentrations was 6-10 km. There were also relationships between concentration and other variables affecting the local components of the concentrations, such as wind direction, sensible heat flux, and vertical wind fluctuation, although the influences were much weaker.Implications: The built environment surrounding major arterials affects the dispersion of vehicular emissions in urban areas, modifying the potential risks to public health. Dispersion of pollutants within the urban canopy is governed by flow and turbulence characteristics caused by building morphometry. Current dispersion models used for regulatory purposes have difficulties simulating the flow and dispersion for complex building cases, especially when fine resolution is needed. Urban planning strategies, such as limitation of building height, pedestrian-friendly community design, or zoning of building structures, modify concentrations of vehicular emissions in built environments surrounding major arterials, which may modify health risks for adjacent communities. IntroductionIn metropolitan cities, vehicular emissions are in close proximity to pedestrians, residences, and local businesses. Current line-source models based on the Gaussian diffusion equation are commonly applied to evaluate the air quality impact of freeways or highways passing through a...

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Comparison of Wind-tunnel and Water-channel Simulations of Plume Dispersion through a Large Array of Obstacles with a Scaled Field Experiment

Cited by 55 publications

References 25 publications

Probabilistic Model for Concentration Fluctuations in Compact-Source Plumes in an Urban Environment

Probabilistic Model for Concentration Fluctuations in Compact-Source Plumes in an Urban Environment

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

Investigation of roadside fine particulate matter concentration surrounding major arterials in five Southern Californian cities

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