The influence of building height variability on pollutant dispersion and pedestrian ventilation in idealized high-rise urban areas

Hang, Jian; Li, Yuguo; Sandberg, Mats; Buccolieri, Riccardo; Sabatino, Silvana Di

doi:10.1016/j.buildenv.2012.03.023

Cited by 324 publications

(137 citation statements)

References 36 publications

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“…A two-dimensional (2D) street canyon is a simplification of an actual urban geometry. Numerous studies have focused on the impact of building characteristics (such as building heights, the shape roof of building, and the density of the building group) on the diffusion of pollutants in idealized and modeling urban street canyons (Li et al, 2008;Huang et al, 2009;Li et al, 2010;Buccolieri et al, 2011;Scargiali et al, 2011;Hang et al, 2012;Addepalli and Pardyjak, 2013;Scungio, 2013;Huang et al, 2015). Scungio et al (2015a) have used the detached eddy simulation to study the turbulent flow in isolated street canyons of different aspect ratios.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Airflow and Particle Dispersion in Street Canyons under Unsteady Thermal Environment with Sinusoidal Variation

Mercola

Wang

Deng

2017

Aerosol Air Qual. Res.

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Unstable temperature stratification conditions have a considerable influence on pollutant diffusion inside street canyons. In this study, we tried to model the air flow and particle dispersion in street canyons under unsteady thermal environment. The sinusoidal variation was used to model the atmosphere temperature on the basis of the solar radiation cycle that occurs over a day. The two-dimensional model of step-up building layouts was applied as the research object and an RNG turbulence model was applied to study the dynamic characteristics of instantaneous airflow, the dimensionless air exchange rate (ACH) and turbulent kinetic energy (TKE) in the different canyons. A series of numerical simulations were performed for different Richardson numbers (Ri). The results demonstrated that the stream function within the street canyons exhibited a periodic shift over a day, and the flow morphology gradually evolved from paralleled bilateral vortexes into a row of vortexes, particularly when the ground temperature increased. Moreover, the local PM concentrations at different times were obtained, and they were affected by the flow field patterns. The total PM mass in the street canyon decreased as the air velocity increased. Furthermore, the dimensionless ACH and TKE exhibit a noticeable fluctuation with time at higher Ri and stronger buoyancy. As the Ri decreases, the enhanced forced convection causes the ACH and TKE to remain constant over time. From these results, inhabitants should be advised to adopt preventative measures aimed at the PM pollution according to the time and location where they live.

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Section: Introductionmentioning

confidence: 99%

Modeling the Airflow and Particle Dispersion in Street Canyons under Unsteady Thermal Environment with Sinusoidal Variation

Mercola

Wang

Deng

2017

Aerosol Air Qual. Res.

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“…Hang et al [7] arranged nine-row and 18-row high-rise square arrays and simulated idealized high-rise urban areas. They sought to understand how the building heights affect the pollutant dispersion and pedestrian ventilation.…”

Section: Introductionmentioning

confidence: 99%

Wind Tunnel Studies of a Pedestrian-Level Wind Environment in a Street Canyon between a High-Rise Building with a Podium and Low-Level Attached Houses

Kuo

Tzeng

Ho³

et al. 2015

Energies

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Abstract:The pedestrian-level wind environment quality in street canyons formed by high-rise buildings and other low-level buildings could be affected by multiple factors, such as the height and geometry of the surrounding buildings, street width, wind direction, and wind speed. This study conducted wind tunnel experiments to determine the characteristics of the pedestrian-level wind environment in street canyons under different conditions, including different street widths, podium heights, and approaching wind directions. The experimental results revealed that the effects of the street canyon width on the pedestrian-level wind in a street canyon can be categorized into three different flow regimes. A higher podium creates stronger wind speeds of the flow within the street canyon, and different approaching wind directions change the high-wind-speed zone within the street canyon accordingly.

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“…Influential factors such as building morphology, canyon aspect ratio, ambient wind speed and direction were intensively studied. Hang et al [6][7][8] investigated the effect of geometry morphology on street canyon ventilation by varying aspect ratio, length and building packing density. They found that lowering aspect ratios or increasing street lengths may enhance the pollutant removal.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Changing Effect on Airflow and Pollutant Dispersion Characteristics in Urban Street Canyons

et al. 2017

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Abstract:In this study, the effect of seasonal variation on air flow and pollutant dispersion characteristics was numerically investigated. A three-dimensional urban canopy model with unit aspect ratio (H/D = 1) was used to calculate surface temperature distribution in the street canyon. Four representative time events (1000 LST, 1300 LST, 1600 LST and 2000 LST) during typical clear summer and winter days were selected to examine the air flow diurnal variation. The results revealed the seasonal variation significantly altered the street canyon microclimate. Compared with the street canyon surface temperature distribution in summer, the winter case showed a more evenly distributed surface temperature. In addition, the summer case showed greater daily temperature fluctuation than that of the winter case. Consequently, distinct pollutant dispersion patterns were observed between summer and winter scenarios, especially for the afternoon (1600 LST) and night (2000 LST) events. Among all studied time events, the pollutant removal performance of the morning (1000 LST) and the night (2000 LST) events were more sensitive to the seasonal variation. Lastly, limited natural ventilation performance was found during the summer morning and the winter night, which induced relatively high pollutant concentration along the pedestrian height level.

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The influence of building height variability on pollutant dispersion and pedestrian ventilation in idealized high-rise urban areas

Cited by 324 publications

References 36 publications

Modeling the Airflow and Particle Dispersion in Street Canyons under Unsteady Thermal Environment with Sinusoidal Variation

Modeling the Airflow and Particle Dispersion in Street Canyons under Unsteady Thermal Environment with Sinusoidal Variation

Wind Tunnel Studies of a Pedestrian-Level Wind Environment in a Street Canyon between a High-Rise Building with a Podium and Low-Level Attached Houses

Seasonal Changing Effect on Airflow and Pollutant Dispersion Characteristics in Urban Street Canyons

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