Effects of low boundary walls under dynamic inflow on flow field and pollutant dispersion in an idealized street canyon

Wang, Le; Pan, Qiang; Zheng, Xiaojing; Yang, Shuo

doi:10.1016/j.apr.2016.12.004

Cited by 16 publications

(8 citation statements)

References 47 publications

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“…Most of the investigated articles do not provide any information on the type of wall treatment used in their studies. Among those that do, however, wall functions are the preferred option, e.g., standard wall function (ANSYS Fluent), fully rough wall function (PHOENICS), nutkRoughWallFunction (OpenFOAM) (e.g., [53,84,86,[105][106][107]). Few studies have used the all-y + wall treatment, of which the most popular is the enhanced wall treatment used in ANSYS Fluent (e.g., [100,[108][109][110]).…”

Section: Wall Treatmentmentioning

confidence: 99%

Air Pollution Dispersion Modelling in Urban Environment Using CFD: A Systematic Review

et al. 2022

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Air pollution is a global problem, which needs to be understood and controlled to ensure a healthy environment and inform sustainable development. Urban areas have been established as one of the main contributors to air pollution, and, as such, urban air quality is the subject of an increasing volume of research. One of the principal means of studying air pollution dispersion is to use computational fluid dynamics (CFD) models. Subject to careful verification and validation, these models allow for analysts to predict air flow and pollution concentration for various urban morphologies under different environmental conditions. This article presents a detailed review of the use of CFD to model air pollution dispersion in an urban environment over the last decade. The review extracts and summarises information from nearly 90 pieces of published research, categorising it according to over 190 modelling features, which are thematically systemised into 7 groups. The findings from across the field are critically compared to available urban air pollution modelling guidelines and standards. Among the various quantitative trends and statistics from the review, two key findings stand out. The first is that, despite the existence of best practice guidelines for pollution dispersion modelling, anywhere between 12% and 34% of the papers do not specify one or more aspects of the utilised models, which are required to reproduce the study. The second is that none of the articles perform verification and validation according to accepted standards. The results of this review can, therefore, be used by practitioners in the field of pollution dispersion modelling to understand the general trends in current research and to identify open problems to be addressed in the future.

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Section: Wall Treatmentmentioning

confidence: 99%

Air Pollution Dispersion Modelling in Urban Environment Using CFD: A Systematic Review

et al. 2022

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“…where C is the pollutant concentration, D is the molecular diffusion coefficient, S is the pollutant source and Sc t is the turbulent Schmidt number. 11 Meshing and case setting…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Moreover, the convective diffusion of pollutants from automobiles is related to the health of residents. [1][2][3][4] At present, research on airflow and pollutant dispersion in urban canopy and street canyons involves many factors, including balconies, 5,6 heat, 7,8 wind environment, 9,10 low boundary walls, 11 car parking systems 12 and trees. 13,14 Because numerical simulation technology consumes fewer resources and obtains abundant data information, 15 various researchers are using numerical simulations of airflow and pollutant dispersion in street canyons under arboreal influence to study airflow and pollutant dispersion in street canyons.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of the effects of canopy properties on airflow and pollutant dispersion in street canyons

Wang

Tian²,

Zhao³

et al. 2021

Indoor and Built Environment

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The air flow and pollutant concentration fields in a street canyon affected by trees could affect the comfort and health of residents. At present, the description of the non-uniform/discontinuous distribution of leaves is difficult. In this study, the leaf distribution in the canopy was characterized by establishing non-continuous (uniform/random) algorithm based on a numerical simulation method, and the effects of canopy properties including, height, porosity and uniform/random leaf distribution, on the airflow and pollutant concentration fields in urban street canyons were investigated. The position of the tree canopy was found to directly affect the airflow field form and the air velocity distribution in the street canyon at low inflows. The average air velocity in the street canyon could be reduced significantly when the top of the tree canopy is near the top of the street canyon. The air velocity and pollutant concentration in the street canyon would vary only slightly due to the canopy porosity. Due to the increasing canopy porosity, the air velocity would increase, and the pollutant concentration would be reduced. The leaves are non-continuous and uniformly distributed at constant porosity, which does not significantly change the velocity distribution and pollutant concentration in the street canyon.

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“…The potential of noise barriers is affected by their size and shape, wind direction, and turbulence; in particular, the barrier height can influence pollutant concentrations at sensors near the barrier [47]. Studies have also identified that solid barriers and low boundary walls have similar effects to those exhibited by vegetation [48,49].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Vegetation Configuration Models for Managing Particulate Matter along the Urban Street Environment

Jeong

Han

Kim

2022

Forests

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As a green infrastructure component, urban street vegetation is increasingly being utilized to mitigate air pollution, control microclimates, and provide aesthetic and ecological benefits. This study investigated the effect of vegetation configurations on particulate matter (PM) flows for pedestrians in road traffic environments via a computation fluid dynamics analysis based on the road width (four and eight-lane) and vegetation configuration (single-, multi-layer planting, and vegetation barrier). Airflow changes due to vegetation influenced PM inflow into the sidewalk. Vegetation between roadways and sidewalks were effective at reducing PM concentrations. Compared to single-layer planting (trees only), planting structures capable of separating sidewalk and roadway airflows, such as a multi-layer planting vegetation barrier (trees and shrubs), were more effective at minimizing PM on the sidewalk; for wider roads, a multi-layer structure was the most effective. Furthermore, along a four-lane road, the appropriate vegetation volume and width for reducing PM based on the breathing height (1.5 m) were 0.6 m3 and 0.4 m, respectively. The appropriate vegetation volume and width around eight-lane roads, were 1.2–1.4 m3 and 0.8–0.93 m, respectively. The results of this study can provide appropriate standards for street vegetation design to reduce PM concentrations along sidewalks.

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Effects of low boundary walls under dynamic inflow on flow field and pollutant dispersion in an idealized street canyon

Cited by 16 publications

References 47 publications

Air Pollution Dispersion Modelling in Urban Environment Using CFD: A Systematic Review

Air Pollution Dispersion Modelling in Urban Environment Using CFD: A Systematic Review

Numerical simulation of the effects of canopy properties on airflow and pollutant dispersion in street canyons

Evaluation of Vegetation Configuration Models for Managing Particulate Matter along the Urban Street Environment

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