Identification of pedestrian-level ventilation corridors in downtown Beijing using large-eddy simulations

Wang, Weiwen; Yang, Tushi; Li, Yanni; Xu, Yuepeng; Chang, Ming; Wang, Xuemei

doi:10.1016/j.buildenv.2020.107169

Cited by 33 publications

(6 citation statements)

References 63 publications

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“…A secondary contributor is waste heat generated by energy usage (Li and Zhao, 2012; Giridharan and Emmanuel, 2018). Much emphasis has been placed on documenting UHIs in modern climate studies, especially in megacities and urban agglomerations around the world (Stewart, 2011; Wang et al ., 2014b; Chen et al ., 2016; Goddard and Tett, 2019; Wang et al ., 2020a; 2020b). Hong Kong is one such high‐density megacity in the hot and humid subtropics.…”

Section: Introductionmentioning

confidence: 99%

Urban heat islands in Hong Kong: Bonding with atmospheric stability

Wang

Chen

et al. 2021

Atmospheric Science Letters

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A barrier to urban heat island (UHI) mitigation is the lack of quantitative attribution of the various contributions to UHI intensity. This study demonstrates the daily and seasonal dynamics of UHIs in Hong Kong, a subtropical highdensity city. The nocturnal UHIs of the city are grouped according to various dynamic stability conditions (neutral, weak stable, and strong stable) of the boundary layer. Results indicate that the stronger the atmospheric stability, the more intense the UHI. The atmospheric anomalies linked to these stability classifications are hence revealed. In summer, nights of neutral (strong stable) stratification are controlled by low (high) pressure with rising (sinking) motion, less (more) precipitation, and lower (higher) air temperature at the surface. In winter, the influence of the large-scale circulation system of the East Asian winter monsoon is significant. In the upper layer, the East Asian jet stream retreats westward (is displaced northward) on nights with neutral (strong stable) atmospheric stratification. At the surface, southeast China is hot and humid on neutral nights, while on strong stable nights, the coastal regions of southeast China are dry, and East Asia is dominated by positive surface air temperature anomalies. Atmospheric anomalies are generally nonsignificant on nights with weak stable stratification in both summer and winter. These findings provide potential predictors for UHI intensity.

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Section: Introductionmentioning

confidence: 99%

Urban heat islands in Hong Kong: Bonding with atmospheric stability

Wang

Chen

et al. 2021

Atmospheric Science Letters

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“…In the last few decades, numerous investigations have been conducted to study urban ventilation [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In the case of street canyons, the flow regimes are different for changing values of the aspect ratio [25,26].…”

Section: Literature Review On Urban Ventilation and Problem Statementmentioning

confidence: 99%

“…Meanwhile, the urban wind environment has been deteriorating, and the urban wind speed has generally declined in most Chinese cities [12]. The trend has been negatively correlated with the urbanization process [13,14]. With the continuous expansion of the city scale, the urban thermal problem has become increasingly apparent, and it directly affects people's thermal safety and comfort.…”

Section: Introduction 1general Backgroundmentioning

confidence: 99%

Assessment of Outdoor Pedestrian Ventilation Performance While Controlling Building Array Scale and Density

Zhang

Cui

2023

Sustainability

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In hot and humid regions of China, people experience great discomfort. Good ventilation improves human comfort by facilitating the discharge of heat in a region. None of the previous studies considered which scale is appropriate for the outdoor ventilation of building arrays, and the ventilation performance differs with the array size. Moreover, the building density has an upper limit in Chinese cities, and many studies overestimate this density. Based on these considerations, the neighborhood block is proposed to represent the scale of building arrays with the combination of the urban planning scale and climatic scale. Using this scale, the building density and representative building array configurations for hot and humid regions of China were determined. The outdoor ventilation of these building arrays at the pedestrian height was then studied via computational fluid dynamics simulations. The results show that, in the neighborhood block, an increase in the building height and length is beneficial for the mean velocity, whereas an increase in the building distance is not, and a staggered layout has a negative effect on ventilation. Furthermore, the semi-enclosed layouts are no better than the enclosed layouts in terms of ventilation and sunlight. Some contributions contradict the existing studies because of the selection of different array scales and densities, which prove their significance.

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“…Previous studies have proved that these aforementioned problems can to some extent be mitigated through appropriate urban planning and designs. In particular, building elevated design (Liu et al, 2017;, building arcade design (Wen et al, 2017), building overhang design (Hang, Chen, et al, 2018), pocket park design (Zhong et al, 2022), and city-scale ventilation corridors (Wang et al, 2020) can make partial improvements to the local or even the urban PLW conditions.…”

Section: Introductionmentioning

confidence: 99%

Recent advances in modeling turbulent wind flow at pedestrian-level in the built environment

Zhong

Liu

Zhao

et al. 2022

ARIN

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Pressing problems in urban ventilation and thermal comfort affecting pedestrians related to current urban development and densification are increasingly dealt with from the perspective of climate change adaptation strategies. In recent research efforts, the prime objective is to accurately assess pedestrian-level wind (PLW) environments by using different simulation approaches that have reasonable computational time. This review aims to provide insights into the most recent PLW studies that use both established and data-driven simulation approaches during the last 5 years, covering 215 articles using computational fluid dynamics (CFD) and typical data-driven models. We observe that steady-state Reynolds-averaged Navier-Stokes (SRANS) simulations are still the most dominantly used approach. Due to the model uncertainty embedded in the SRANS approach, a sensitivity test is recommended as a remedial measure for using SRANS. Another noted thriving trend is conducting unsteady-state simulations using high-efficiency methods. Specifically, both the massively parallelized large-eddy simulation (LES) and hybrid LES-RANS offer high computational efficiency and accuracy. While data-driven models are in general believed to be more computationally efficient in predicting PLW dynamics, they in fact still call for substantial computational resources and efforts if the time for development, training and validation of a data-driven model is taken into account. The synthesized understanding of these modeling approaches is expected to facilitate the choosing of proper simulation approaches for PLW environment studies, to ultimately serving urban planning and building designs with respect to pedestrian comfort and urban ventilation assessment.

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Identification of pedestrian-level ventilation corridors in downtown Beijing using large-eddy simulations

Cited by 33 publications

References 63 publications

Urban heat islands in Hong Kong: Bonding with atmospheric stability

Urban heat islands in Hong Kong: Bonding with atmospheric stability

Assessment of Outdoor Pedestrian Ventilation Performance While Controlling Building Array Scale and Density

Recent advances in modeling turbulent wind flow at pedestrian-level in the built environment

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