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

Dong, Jingliang; Tan, Zijing; Xiao, Yimin; Tu, Jiyuan

doi:10.3390/atmos8030043

Cited by 17 publications

(7 citation statements)

References 52 publications

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“…Turbulence modelling is a core issue to address in CFD and it poses unique challenges for flows in the urban infrastructure [10]. The large size of buildings and high velocities of the atmospheric boundary layer result in highly turbulent flows [11], which are computationally expensive to concentration levels, exhibiting fair agreement with the experimental data, except from slight underestimation for the concentration fluctuations near the source.…”

Section: Introductionmentioning

confidence: 99%

Qualitative and Quantitative Investigation of Multiple Large Eddy Simulation Aspects for Pollutant Dispersion in Street Canyons Using OpenFOAM

et al. 2019

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Air pollution is probably the single largest environment risk to health and urban streets are the localized, relevant hotspots. Numerous studies reviewed the state-of-the-art models, proposed best-practice guidelines and explored, using various software, how different approaches (e.g., Reynolds-averaged Navier–Stokes (RANS), large eddy simulations (LES)) inter-compare. Open source tools are continuously attracting interest but lack of similar, extensive and comprehensive investigations. At the same time, their configuration varies significantly among the related studies leading to non-reproducible results. Therefore, the typical quasi-2D street canyon geometry was selected to employ the well-known open-source software OpenFOAM and to investigate and validate the main parameters affecting LES transient simulation of a pollutant dispersion. In brief, domain height slightly affected street level concentration but source height had a major impact. All sub-grid scale models predicted the velocity profiles adequately, but the k-equation SGS model best-resolved pollutant dispersion. Finally, an easily reproducible LES configuration is proposed that provided a satisfactory compromise between computational demands and accuracy.

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Section: Introductionmentioning

confidence: 99%

Qualitative and Quantitative Investigation of Multiple Large Eddy Simulation Aspects for Pollutant Dispersion in Street Canyons Using OpenFOAM

et al. 2019

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“…Canyons with a unity aspect ratio (case (i) in Table 1) have been studied extensively in the literature, both experimentally [36,38,39,41] and numerically [31,[42][43][44]. We repeated the measurements of this reference case to verify that our experimental setup can reproduce the results in the literature.…”

Section: Reference Case With Canyons Of Aspect Ratiomentioning

confidence: 89%

Pedestrian-Level Urban Wind Flow Enhancement with Wind Catchers

2017

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Dense urban areas restrict air movement, causing airflow in urban street canyons to be much lower than the flow above buildings. Boosting near-ground wind speed can enhance thermal comfort in warm climates by increasing skin convective heat transfer. We explored the potential of a wind catcher to direct atmospheric wind into urban street canyons. We arranged scaled-down models of buildings with a wind catcher prototype in a water channel to simulate flow across two-dimensional urban street canyons. Velocity profiles were measured with Acoustic Doppler Velocimeters. Experiments showed that a wind catcher enhances pedestrian-level wind speed in the target canyon by 2.5 times. The flow enhancement is local to the target canyon with little effect in other canyons. With reversed flow direction, a "reversed wind catcher" has no effect in the target canyon but reduces the flow in the immediate downstream canyon. The reversed wind catcher exhibits a similar blockage effect of a tall building amid an array of lower buildings. Next, we validated Computational Fluid Dynamics (CFD) simulations of all cases with experiments and extended the study to reveal impacts on three-dimensional ensembles of buildings. A wind catcher with closed sidewalls enhances maximum pedestrian-level wind speed in three-dimensional canyons by four times. Our results encourage better designs of wind catchers to increase wind speed in targeted areas.

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“…Dong et al [13] analyzed the impact of seasonal changes, including solar radiation and anthropogenic heating effects, on an idealized urban canyon ventilation, as well as pollutant dispersion characteristics by CFD simulations. Results show a more evenly distributed surface temperature with relatively weak diurnal fluctuation in winter.…”

Section: Effects Of Urban Morphology and Obstacles To Ventilationmentioning

confidence: 99%