A parametric study of angular road patterns on pedestrian ventilation in high-density urban areas

He, Yueyang; Tablada, Abel; Wong, Nyuk Hien

doi:10.1016/j.buildenv.2019.01.047

Cited by 44 publications

(13 citation statements)

References 60 publications

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“…Shen et al [ 11 ] assessed pedestrian and street canyon ventilation using indices such as net escape velocity and age of air for six irregular real-world cases under the wind direction parallel to the street and concluded that octagon and oblique intersections were favorable for central street ventilation. He et al [ 12 ] conducted a numerical parametric study on pedestrian ventilation at four-way street intersections of 13 angular patterns within a high-rise urban area, confirming the effect of both the prevailing wind direction and the relative orientation of adjacent street segments and concluded that moderate angles for downstream segments help balance the downstream and lateral flow penetrations. Guo et al [ 21 ] simulated pollutant dispersion and ventilation, particularly at street and pedestrian levels, by normalized concentration and net escape velocity, at three types of intersections with different green configurations, and reported that the presence of greening could worsen the pollutant conditions at intersections to different extents because of the change in intersection typologies and approaching wind directions.…”

Section: Introductionmentioning

confidence: 98%

“…The street ends and intersections are noticeably more complex than the two-dimensional middle slice of the canyon. However, chamfering [ 11 ], setback [ 12 ], and disjointing [ 13 ] of buildings at street corners may help enlarge the space to a certain extent. Thus, more sophisticated flow form at street ends and intersections, as evidenced by three-dimensional vortices and the complex stratification of velocity.…”

Section: Introductionmentioning

confidence: 99%

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Ventilation and Pollutant Concentration for the Pedestrian Zone, the Near-Wall Zone, and the Canopy Layer at Urban Intersections

Zhang

Gao

Guo

et al. 2021

IJERPH

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To gain further insight into the ventilation at urban street intersections, this study conducted 3D simulations of the ventilation at right- and oblique-angled intersections under eight wind directions by using the Reynolds-averaged Navier–Stokes (RANS) κ-ε turbulence model. The divergent responses of ventilation and pollution concentration for the pedestrian zone (ped), the near-wall zone (nwz), and the canopy layer to the change in intersection typology and wind direction were investigated. The flow characteristics of the intersections, taken as the air flow hub, were explored by employing indices such as the minimum flow ratio (β) between horizontal openings. The results show that oblique wind directions lead to a lower total volumetric flow rate (Qtotal) but a higher β value for right-angled intersections. For T-shaped intersections, a larger cross-sectional area for the outflow helps to increase Qtotal. Oblique-angled intersections, for example, the X-shaped intersection, experience a more significant difference in Qtotal but a steady value of β when the wind direction changes. The vertical air-exchange rate for the intersection was particularly significant when the wind directions were parallel to the street orientation or when there was no opening in the inflow direction. The spatially averaged normalized pollutant concentration and age of air (τ*¯) for the pedestrian zone and the canopy layer showed similar changing trends for most of the cases, while in some cases, only the τped*¯ or τnwz*¯ changed obviously. These findings reveal the impact mechanism of intersection configuration on urban local ventilation and pollutant diffusion.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Ventilation and Pollutant Concentration for the Pedestrian Zone, the Near-Wall Zone, and the Canopy Layer at Urban Intersections

Zhang

Gao

Guo

et al. 2021

IJERPH

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“…Numerous studies have found that the effect is closely related to urban anthropogenic heat release, underlying surface properties and structure, vegetation coverage, population density, and weather conditions. Among many factors, urban ventilation conditions caused by the underlying surface properties and structure have a significant impact on the UHI effect [16][17][18][19][20]. In order for governments and city planners to make planning decisions intuitively, quantitative methods are needed to determine ventilation paths in urban planning [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

A Least Cumulative Ventilation Cost Method for Urban Ventilation Environment Analysis

Xie

Liu

2020

Complexity

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The correct urban building layout is an important influencing factor in urban ventilation, and the heat island effect has become an important factor affecting the quality of urban life. Optimization of the urban building layout can play a role in mitigating the heat island effect. The traditional ventilation corridor analysis method, based on a least-cost path analysis, can only generate a few main ventilation corridors. It is difficult to obtain global ventilation results covering the whole study area using this method of analysis. On the basis of urban morphology and a least-cost path analysis, this study proposes a “least cumulative ventilation cost” method for analyzing urban ventilation. Taking Wuhan downtown as a research area, the urban ventilation environment under different wind directions and seasons was analyzed. This method can effectively express the ventilation conditions throughout the whole study area and can simultaneously express the quality of the generated corridors effectively. The results show that Wuhan has three levels of ventilation corridor. Moreover, the ventilation conditions in Wuchang (Wuchang, Qingshan, and Hongshan) are better than those in Hankou (Qiaokou, Jianghan, and Jiang’an).

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“…Some researchers have utilized "arrays" to predict the impact on a wind environment of proposed buildings in the surrounding areas [18,19] (Figure 1a). Some researchers have utilized "along streets" to study the distribution of wind in the height direction in the streets [20,21] (Figure 1b). Some researchers have utilized "around buildings" arrangements to study a wind environment around buildings [19,22,23] (Figure 1c).…”

Section: Introductionmentioning

confidence: 99%

“…Some researchers have utilized "distributed" arrangements to perform the wind environment assessment for built-up areas [24,25] (Figure 1d). In the wind tunnel experiments, authors have used different arrangements of measurement points for different research objectives [18][19][20][21][22][23][24][25]. These four main arrangements of measurement points take into consideration some urban spatial characteristics (such as streets), but because their research purpose is not based on the characteristics of the urban space, the arrangements do not fully reflect the characteristics of the urban space.…”

Section: Introductionmentioning

confidence: 99%

A Wind Tunnel Study on the Correlation between Urban Space Quantification and Pedestrian–Level Ventilation

Peng

et al. 2019

Atmosphere

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Correlation research on urban space and pedestrian–level wind (PLW) environments is helpful for improving the wind comfort in complex urban space. It could also be significant for building and urban design. Correlation research is usually carried out in a space with clear urban spatial characteristics, so it is necessary to define the space first. In this paper, a typical urban area in Nanjing, China, is selected as the research object, and a spatial partition method is used to divide the real complex urban space into subspaces. The urban spatial characteristics of such subspaces are quantified using three urban spatial indices: openness (O), area (A), and shape (S). By comparing the quantitative results, 24 (12 pairs) subspaces with prominent urban spatial indices are selected as the correlation research cases. The 24 subspaces also provide a reference for the layout of the measurement points in a wind tunnel experiment. This is a new arrangement for locating the measurement points of a wind tunnel for correlation research. In the experiment, 45 measurement points are located, and the mean wind velocity of four different wind directions at 45 measurement points is experimented. The results clearly show that, when the experimental conditions are the same, the changes of mean wind velocity ratio (UR) of 24 (12pairs) subspaces under the four experimental wind directions are close. The URs of the subspaces are not significantly affected by the wind direction, which is affected more by the subspaces’ spatial characteristics. When making the correlation analysis between mean wind speed ratio and spatial characteristics’ indices, a direct numerical comparison was not able to find a correlation. By comparing the difference values of mean wind speed (△UR) and indices between each pair of subspaces, the correlation between UR and openness of subspaces were found. Limited by spatial partition method, the correlation between UR and the other indices was not obvious.

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A parametric study of angular road patterns on pedestrian ventilation in high-density urban areas

Cited by 44 publications

References 60 publications

Ventilation and Pollutant Concentration for the Pedestrian Zone, the Near-Wall Zone, and the Canopy Layer at Urban Intersections

Ventilation and Pollutant Concentration for the Pedestrian Zone, the Near-Wall Zone, and the Canopy Layer at Urban Intersections

A Least Cumulative Ventilation Cost Method for Urban Ventilation Environment Analysis

A Wind Tunnel Study on the Correlation between Urban Space Quantification and Pedestrian–Level Ventilation

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