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

Abstract

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.

Application of CFD Modelling for Pollutant Dispersion at an Urban Traffic Hotspot

“…Tominaga et al (2008) [21] suggested a domain height of 6 H with H being the height of the target building. Pantusheva et al (2022) [22], when reviewing common practices followed on CFD applications, found that a minimum 6 H height was used in 57% of the cases and an upstream distance of at least 5 H in 46% of the cases. Therefore, for this work, a domain height of 350 m was used (>6 H) and the distance between the boundaries and the closest building on each side was 300 m (>5 H), creating a domain of 1250 × 1650 m 2 in size.…”

URANS Simulations of Vehicle Exhaust Plumes with Insight on Remote Emission Sensing

“…Assuming that the exhaust plume is well mixed, the optical path length l can be considered to be the same for each species, so that, e.g., for NO x and CO 2 l NO x = l CO 2 (17) applies and the concentration ratio can be rewritten as…”

“…Moreover, ref. [17] provides a good overview of recent CFD studies investigating pollutant dispersion.…”

Sensitivity Analysis of Modelled Air Pollutant Distribution around Buildings under Different Meteorological Conditions

“…e.g., [10][11][12][13][14]. The approaches employed exhibit a range of degrees of complexity, including semi-empirical models [15,16], dispersion models with specific parameterisations for the urban area [17], Lagrangian models [18,19], chemical transport models (CTMs) coupled with microscale Lagrangian or Gaussian models [20,21], and complex computational fluid dynamics (CFDs) models [3,14,[22][23][24][25]. Semi-empirical models, exemplified by the Operational Street Pollution Model (OSPM) [16], make prior assumptions about flow and dispersion conditions within street canyons based on experimental data.…”