Статті в журналах: "Street Canyon Ventilation"

1

Kluková, Zuzana, Štěpán Nosek, and Vladimír Fuka. "Capability of air exchange rate to predict ventilation of three-dimensional street canyons." EPJ Web of Conferences 213 (2019): 02042. http://dx.doi.org/10.1051/epjconf/201921302042.

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As most of the world’s population lives in cities, it is critical to understand dispersion processes of pollutants in urban areas. This study focuses on so called air exchange rate (ACH) index, which is frequently used by numerical studies to determine ventilation of street canyons without a simulation of a pollution source. These studies applied the ACH on idealised 2D street canyons, where the ventilation acts only through the one opening roof top. There are two pertinent questions: i) is the ACH really capable to predict the ventilation of a street canyon without knowing of a pollutant source; and ii) how much the ACH differs between 2D and 3D street canyons? To answer these questions, we performed large-eddy simulations of pollution of complex 3D street canyons from ground-level line sources. We computed ACHs and spatially-average concentrations for three different street canyons and compared these quantities with those from previous studies. Results clearly demonstrate that these quantities strongly depend not only on street-canyon geometry but also on geometry of surrounding buildings. It is also shown that 2D canyon gives unrealistic result for retention of pollutant within an urban street canyon. The ACH might lead to significant underestimation of the street-canyon ventilation if a source would be outside the canyon.

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2

Zhang, Ning Bo, Yan Ming Kang, Ke Zhong, and Jia Ping Liu. "Numerical Modeling of the Flow and Pollutant Dispersion in Street Canyons with Ground Thermal Effect." Applied Mechanics and Materials 548-549 (April 2014): 601–6. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.601.

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Thermal stratification affects the flow in and above urban street canyons. Such thermal effect is often not noticed, and can lead to pessimistic or optimistic results of the air quality in urban street canyons under calm conditions and low wind speeds. A three-dimensional CFD model is applied to simulate the flow patterns and particle concentrations in a street canyon under different aspect ratios and ground thermal conditions. The model is validated by the experimental data found in the literature. The simulation results are used to evaluate the flow and pollutant dispersion properties in the canyon. The results show that the ground thermal conditions can significantly affect the ventilation performance of the street canyon, which improves with the increased temperature difference (ΔT) between the ambient air and the ground of the canyon. The increased ΔT enhances the buoyancy induced secondary flow in the street canyon and hence reduce the particle concentrations in the canyon, with this influence more pronounced for small street widths.

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3

Salizzoni, P., L. Soulhac, and P. Mejean. "Street canyon ventilation and atmospheric turbulence." Atmospheric Environment 43, no. 32 (October 2009): 5056–67. http://dx.doi.org/10.1016/j.atmosenv.2009.06.045.

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4

Miao, Yucong, Shuhua Liu, Yijia Zheng, Shu Wang, and Yuan Li. "Numerical Study of Traffic Pollutant Dispersion within Different Street Canyon Configurations." Advances in Meteorology 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/458671.

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The objective of this study is to numerically study flow and traffic exhaust dispersion in urban street canyons with different configurations to find out the urban-planning strategies to ease the air pollution. The Computational Fluid Dynamics (CFD) model used in this study—Open Source Field Operation and Manipulation (OpenFOAM) software package—was firstly validated against the wind-tunnel experiment data by using three differentk-εturbulence models. And then the patterns of flow and dispersion within three different kinds of street canyon configuration under the perpendicular approaching flow were numerically studied. The result showed that the width and height of building can dramatically affect the pollution level inside the street canyon. As the width or height of building increases, the pollution at the pedestrian level increases. And the asymmetric configuration (step-up or step-down street canyon) could provide better ventilation. It is recommended to design a street canyon with nonuniform configurations. And the OpenFOAM software package can be used as a reliable tool to study flows and dispersions around buildings.

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5

Jiang, Guoyi, Tingting Hu, and Haokai Yang. "Effects of Ground Heating on Ventilation and Pollutant Transport in Three-Dimensional Urban Street Canyons with Unit Aspect Ratio." Atmosphere 10, no. 5 (May 21, 2019): 286. http://dx.doi.org/10.3390/atmos10050286.

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A validated standard k-ε model was used to investigate the effects of ground heating on ventilation and pollutant transport in a three-dimensional (3D) street canyon. Air entered the street canyon from the upper regions of side surfaces and most areas of the top surface and left from the lower regions of side surfaces. Ground heating enhanced the mean flow, ventilation, and turbulence, and facilitated pollutant reduction inside street canyons. The transport patterns in a street canyon that included a pollutant source (PSC) and a target street canyon downstream (TSC) were different. The pollutant did not enter the PSC, and turbulent diffusion dominated pollutant outflow at all boundaries. The pollutant entered the TSC from most regions of the side surfaces and exited from lower regions of the side surfaces and the entire top surface. Air convection dominated pollutant transport at the side surfaces, and its contribution increased significantly with ground temperature; Furthermore, turbulent diffusion dominated pollutant outflow for the top surface, and its contribution increased slightly with ground heating. As revealed by an analysis of both the total pollutant flow rates and air flow rates, although air/pollutant exchange between the TSC and outer space occurred primarily through the side surfaces, the increase in air inflow from the top surface reduced the pollutant concentration inside the street canyon when the ground temperature increased. The top surface played a major role in improving air quality in a 3D environment with ground dispersion. This study supplied valuable suggestions for urban planning strategies. The analyzing method used in this research is helpful for the pollutant transport investigations in urban areas.

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6

Huang, Tzu-Ling, Chien-Yuan Kuo, Chun-Ta Tzeng, and Chi-Ming Lai. "The Influence of High-Rise Buildings on Pedestrian-Level Wind in Surrounding Street Canyons in an Urban Renewal Project." Energies 13, no. 11 (May 30, 2020): 2745. http://dx.doi.org/10.3390/en13112745.

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The pedestrian wind environment in a street canyon is affected by a multitude of factors, including the height and geometric shape of the surrounding buildings, the street width, the wind direction, and speed. Wind-tunnel tests were performed to determine the effects of constructing high buildings in an urban renewal project in New Taipei City, Taiwan on the pedestrian wind environments in the surrounding street canyons. The results show that replacing the original low-rise buildings with high-rise buildings could decrease the wind speed and natural ventilation potential in certain surrounding street canyons. The flow fields generated by approaching winds in various street canyons are highly complex in this practical case study. Thus, the pedestrian wind patterns in the street canyons cannot be interpreted in terms of channeling and shielding effects alone, as is typically reported in the literature.

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7

Liu, Cheng-Wei, Shuo-Jun Mei, Di Liu, and Fu-Yun Zhao. "Convective dispersion of heat and airborne pollutants inside street canyons under the influence of urban ground heat flows." Indoor and Built Environment 28, no. 5 (April 26, 2017): 619–35. http://dx.doi.org/10.1177/1420326x17706186.

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This paper reports a computational fluid dynamics simulation of airflow and species dispersion inside street canyons and building blocks simultaneously. Urban thermal boundary flows could cause a profound effect on the dispersion of pollutant scalars and ventilation performance of street canyons. Nominal pollutant concentration differences between the urban street canyon and the countryside fresh air could be determined by a consideration of wind profile and ground vegetation. This study models the interaction of the fluid flow, thermal and pollutant dispersions based on the Reynolds number (Re), Grashof number (Gr) and their combinations – Archimedes number (Ar). The fluid, heat and pollutant dispersion performances were compared with the air, heat and pollutant removal efficiencies, indicated by the air change rate (ACR), heat removal rate (HRR) and pollutant removal rate (PRR). Numerical results indicate that Ar could promote fluid, heat and pollutant removals in street canyons. Transport function lines (contours of heat and mass functions) produced would illustrate the main recirculation developed inside these street canyons studied, to allow development of control strategies for dispersion of heat and pollutant species within these environments. The present work could contribute towards the understanding of the ventilation mechanism in street canyons surrounded by the residential buildings.

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8

Lo, K. W., and K. Ngan. "Characterizing Ventilation and Exposure in Street Canyons Using Lagrangian Particles." Journal of Applied Meteorology and Climatology 56, no. 5 (May 2017): 1177–94. http://dx.doi.org/10.1175/jamc-d-16-0168.1.

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AbstractThe residence time measures the rate at which a pollutant escapes from a region of interest. Previous studies of urban ventilation have estimated the mean residence time from Eulerian data by assuming a spatially homogeneous pollutant field. Using a large-eddy simulation and a Lagrangian particle model, the residence and exposure times are calculated for an idealized street canyon in the skimming-flow region and a deep street canyon within a realistic urban area. For both domains, the mean residence time is on the order of a canyon circulation time scale, while the mean exposure time, which includes re-entrainment and characterizes the total time spent by a pollutant in a region of interest, is about 20% longer. Intensive quantities such as the Lagrangian visitation factor and return coefficient indicate that re-entrainment is modest. Probability distribution functions of the exposure and residence times are nearly exponential for both domains, in accord with pure diffusion and single-time-scale, vertical-exchange parameterizations. It is argued that, by analogy with Brownian motion, the mean residence and exposure times are set primarily by the mean circulation rather than the turbulence when the flow approximates that within a two-dimensional street canyon.

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9

Nosek, Štěpán, Libor Kukačka, Radka Kellnerová, Klára Jurčáková, and Zbyněk Jaňour. "Ventilation Processes in a Three-Dimensional Street Canyon." Boundary-Layer Meteorology 159, no. 2 (February 1, 2016): 259–84. http://dx.doi.org/10.1007/s10546-016-0132-2.

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10

Ng, Chi To, and Chun Ho Liu. "Numerical simulations of street canyon ventilation and pollutant dispersion." International Journal of Environment and Pollution 55, no. 1/2/3/4 (2014): 167. http://dx.doi.org/10.1504/ijep.2014.065921.

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11

Balakin, V. V. "Street canyon ventilation control by proper planning and development." Vestnik MGSU, no. 5 (May 2014): 108–18. http://dx.doi.org/10.22227/1997-0935.2014.5.108-118.

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12

Liu, Jing, Zhiwen Luo, Taoyao Zhao, and Jing Shui. "Ventilation in a Street Canyon under Diurnal Heating Conditions." International Journal of Ventilation 11, no. 2 (September 2012): 141–54. http://dx.doi.org/10.1080/14733315.2012.11683977.

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13

Buccolieri, Riccardo, Oliver Savio Carlo, Esther Rivas, and Jose Luis Santiago. "Urban Obstacles Influence on Street Canyon Ventilation: A Brief Review." Environmental Sciences Proceedings 8, no. 1 (June 22, 2021): 11. http://dx.doi.org/10.3390/ecas2021-10350.

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Many research articles explore new designs and how to arrange barriers/obstacles to improve roadside air quality and ventilation within the urban street canyon. These obstacles are generally categorized into porous, non-porous and mixed type. Porous barriers include vegetated shrubs and trees; non-porous barriers include parked cars, low boundary walls, etc., while mixed barriers combine both porous and non-porous barriers. Moreover, new developments can benefit from added design flexibility using lift-up building design and building porosity as a promising way of improving ventilation. This short paper reviews the different research studies conducted on obstacles/barriers in an urban canyon which helps improve air quality and also highlights potential future research.

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14

Tay, B. K., G. B. McFiggans, D. P. Jones, M. W. Gallagher, C. Martin, P. Watkins, and R. M. Harrison. "Linking aerosol fluxes in street canyons to urban city-scale emissions." Atmospheric Chemistry and Physics Discussions 9, no. 5 (September 1, 2009): 18065–112. http://dx.doi.org/10.5194/acpd-9-18065-2009.

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Abstract. In this study we investigate ultrafine particle (UFP) fluxes using a first order eddy viscosity turbulence closure Computational Fluid Dynamics (CFD) model and determine the different factors that influence emissions of UFP into the urban boundary layer. Both vertical turbulent fluxes as well as the fluxes due to mean flow are shown to contribute to the overall ventilation characteristics of street canyons. We then derive a simple parameterised numerical prediction model for canyon top UFP venting which is then compared with tower based micrometeorological flux measurements obtained during the REPARTEE and CityFlux field experiments.

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15

Hassan, Sheikh, Umma Habiba Akter, Preetom Nag, Md Mamun Molla, Amirul Khan, and Md Farhad Hasan. "Large-Eddy Simulation of Airflow and Pollutant Dispersion in a Model Street Canyon Intersection of Dhaka City." Atmosphere 13, no. 7 (June 28, 2022): 1028. http://dx.doi.org/10.3390/atmos13071028.

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The atmospheric flow and dispersion of traffic exhaust were numerically studied in this work while considering a model street canyon intersection of a city. The finite volume method (FVM)-based large-eddy simulation (LES) technique in line with ANSYS Fluent have been used for flow and pollutant dispersion modelling through the consideration of the atmospheric boundary layer (ABL). Hexahedral elements are considered for computational domain discretization in order to numerically solve problems using FVM-LES. The turbulence parameters were superimposed through a spectral synthesizer in the existing LES model through ANSYS Fluent as part of ’damage control’ due to the unsteady k−ϵ simulation. Initially, the code is validated with an experimental study of an urban street canyon where the width and height ratio is in unity. After validation, a model urban street canyon intersection was investigated in this work. The model shows a high pollutant concentration in the intersecting corner areas of the buildings. Additionally, the study of this model intersection shows a high level of pollutant concentration at the leeward wall of downwind building in the case of increased height of an upwind building. Most importantly, it was realized from the street intersection design that three-dimensional interconnection between the dominating canyon vortices and roof level flow plays a pivotal role in pollutant concentration level on the windward walls. The three-dimensional extent of corner eddies and their interconnections with dominating vortices were found to be extremely important as they facilitate enhanced ventilation. Corner eddies only form for the streets towards the freeway and not for the streets towards the intersection. The results and key findings of this work offer qualitative and quantitative data for the estimation, planning, and implementation of exposure mitigation in an urban environment.

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16

Tay, B. K., G. B. McFiggans, D. P. Jones, M. W. Gallagher, C. Martin, P. Watkins, and R. M. Harrison. "Linking urban aerosol fluxes in street canyons to larger scale emissions." Atmospheric Chemistry and Physics 10, no. 5 (March 11, 2010): 2475–90. http://dx.doi.org/10.5194/acp-10-2475-2010.

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Abstract. In this study we investigate ultrafine particle (UFP) fluxes using a first order eddy viscosity turbulence closure Computational Fluid Dynamics (CFD) model and determine the different factors that influence emissions of UFP into the urban boundary layer. Both vertical turbulent fluxes as well as the fluxes due to mean circulatory flow are shown to contribute to the overall ventilation characteristics of street canyons. We then derive a simple parameterised numerical prediction model for canyon top UFP venting which is then compared with tower based micrometeorological flux measurements obtained during the REPARTEE & CityFlux field experiments.

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17

Kluková, Zuzana, Štěpán Nosek, Zbyněk Jaňour, and Libor Kukačka. "Lateral transport of traffic pollutants in complex urban area." EPJ Web of Conferences 180 (2018): 02125. http://dx.doi.org/10.1051/epjconf/201818002125.

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Owing to the spatial variability of an urban area, even the transport of passive scalar is complex. The examination of the pollutant transport in such turbulent flow as occur within the urban canopy requires the measurements not only the advective but also the turbulent part of this transport. However, recent measurement techniques for the turbulent transport have their limitations. In particular, these measurements are very demanding if one needs to analyze the ventilation processes of the street through the entire streetcanyon openings and which needs to be performed also in the positions where the handling with the measurement instruments might comprise a complex issue or is even impossible. Thus we present a comparison of two methods for the assessment of turbulent and advective pollution fluxes through the lateral openings of two different street canyons with respect to the wind direction and the roof-height nonuniformity to evaluate the importance of the measurement of these fluxes nearby the street-canyon walls. Both of them are based on the simultaneous point measurement of concentration and lateral velocity component and the interpolation between the last measured point and the street-canyon borders, but in the second method the measured area is extended from 77% to 84% of the total area of the lateral openings.

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18

Mohammadi, Murtaza, and John Calautit. "Impact of Ventilation Strategy on the Transmission of Outdoor Pollutants into Indoor Environment Using CFD." Sustainability 13, no. 18 (September 16, 2021): 10343. http://dx.doi.org/10.3390/su131810343.

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The transition to remote working due to the pandemic has accentuated the importance of clean indoor air, as people spend a significant portion of their time indoors. Amongst the various determinants of indoor air quality, outdoor pollution is a significant source. While conventional studies have certainly helped to quantify the long-term personal exposure to pollutants and assess their health impact, they have not paid special attention to the mechanism of transmission of pollutants between the two environments. Nevertheless, the quantification of infiltration is essential to determine the contribution of ambient pollutants in indoor air quality and its determinants. This study evaluates the transmission of outdoor pollutants into the indoor environment using 3D computational fluid dynamics modelling with a pollution dispersion model. Naturally ventilated buildings next to an urban canyon were modelled and simulated using Ansys Fluent and validated against wind tunnel results from the Concentration Data of Street Canyons database. The model consisted of two buildings of three storeys each, located on either side of a road. Two line-source pollutants were placed in the street, representing traffic emissions. Three internal rooms were selected and modelled on each floor and implemented with various ventilation strategies. Results indicate that for a canyon with an aspect ratio of 1, indoor spaces in upstream buildings are usually less polluted than downstream ones. Although within the canyon, pollution is 2–3 times higher near the upstream building. Cross ventilation can minimise or prevent infiltration of road-side pollutants into indoor spaces, while also assisting in the dispersion of ambient pollutants. The critical configuration, in terms of air quality, is single-sided ventilation from the canyon. This significantly increases indoor pollutant concentration regardless of the building location. The study reveals that multiple factors determine the indoor–outdoor links, and thorough indexing and understanding of the processes can help designers and urban planners in regulating urban configuration and geometries for improved indoor air quality. Future works should look at investigating the influence of indoor emissions and the effects of different seasons.

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19

Witri, Afiq Muhammad Yazid, Nor Azwadi Che Sidik, and Salim Mohamed Salim. "Numerical Simulation of Wind Flow Structures and Pollutant Dispersion within Street Canyon under Thermally Unstable Atmospheric Conditions." Applied Mechanics and Materials 554 (June 2014): 655–59. http://dx.doi.org/10.4028/www.scientific.net/amm.554.655.

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Numerical studies were conducted to envisage the wind flow structures in street canyon for differential heated wall and Richardson numbers. Two-equation turbulence models, namely the Standard k-ε, Renormalization Group (RNG) k-ε and Realizable k-ε were applied to investigate the effect of flow structure on pollutant dispersion in a square street canyon. The obtained results demonstrate that the differentially heated wall/floor gives significant effects on the wind flow field compared with those under isothermal conditions. At low Richardson number, vortex intensification was observed for the case of ground or leeward heated wall. Meanwhile, for the case of windward heated wall, the ventilation was much reduced due to the buoyancy force that produces upward motion near the wall to form the secondary vortex. At higher Froude number (convective flows) case, the buoyancy flow has no discernible effects on the flow structures. Keywords— Street canyon; thermal flow; wind flow structures; pollutant dispersion; turbulence models

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20

Xu, Fusuo, Zhi Gao, and Jianshun Zhang. "Effects of roadside morphologies and moving vehicles on street canyon ventilation." Building and Environment 218 (June 2022): 109138. http://dx.doi.org/10.1016/j.buildenv.2022.109138.

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21

Park, Seung-Bu, Jong-Jin Baik, and Sang-Hyun Lee. "Impacts of Mesoscale Wind on Turbulent Flow and Ventilation in a Densely Built-up Urban Area." Journal of Applied Meteorology and Climatology 54, no. 4 (April 2015): 811–24. http://dx.doi.org/10.1175/jamc-d-14-0044.1.

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AbstractTurbulent flow in a densely built-up area of Seoul, South Korea, for 0900–1500 LST 31 May 2008 is simulated using the parallelized large-eddy simulation model (PALM) coupled to a mesoscale model (Weather Research and Forecasting Model). Time-varying inflow that is composed of mesoscale wind and turbulent signals induces different mean flows and turbulence structures depending on time. Sweeps induced by upper flow are distinct for 0900–0910 LST, and strong ejections and weaker sweeps are dominant for 1450–1500 LST at height z = 200 m. To investigate pedestrian wind environment and ventilation, mean wind velocity and turbulent kinetic energy at 2.5 m above streets are analyzed. The reference mean wind speed at z = 600 m continuously increases after 1010 LST. The pedestrian mean streamwise velocity tends to decrease after 1100 LST, although the pedestrian mean wind speed tends to slowly increase. Whereas the temporal velocity variations related to mesoscale wind are distinct in a street canyon and an intersection, the variations induced by mesoscale wind disappear in a dense building area, indicating strong decoupling from mesoscale wind. The velocity ratio of the pedestrian mean wind speed to the reference mean wind speed, representing a measure of ventilation in urban areas, is high on broad streets and at intersections and is low in dense building areas. Vortices in street canyons and winding flows around tall buildings seem to induce high velocity ratio there. The velocity ratio is shown to be linearly proportional to the pedestrian mean streamwise velocity.

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22

Nelson, M. A., E. R. Pardyjak, J. C. Klewicki, S. U. Pol, and M. J. Brown. "Properties of the Wind Field within the Oklahoma City Park Avenue Street Canyon. Part I: Mean Flow and Turbulence Statistics." Journal of Applied Meteorology and Climatology 46, no. 12 (December 1, 2007): 2038–54. http://dx.doi.org/10.1175/2006jamc1427.1.

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Abstract Velocity data were obtained from sonic anemometer measurements within an east–west-running street canyon located in the urban core of Oklahoma City, Oklahoma, during the Joint Urban 2003 field campaign. These data were used to explore the directional dependence of the mean flow and turbulence within a real-world street canyon. The along-canyon vortex that is a key characteristic of idealized street canyon studies was not evident in the mean wind data, although the sensor placement was not optimized for the detection of such structures. Instead, surface wind measurements imply that regions of horizontal convergence and divergence exist within the canopy, which are likely caused by taller buildings diverting the winds aloft down into the canopy. The details of these processes appear to be dependent on relatively small perturbations in the prevailing wind direction. Turbulence intensities within the canyon interior appeared to have more dependence on prevailing wind direction than they did in the intersections. Turbulence in the intersections tended to be higher than was observed in the canyon interior. This behavior implies that there are some fundamental differences between the flow structure found in North American–style cities where building heights are typically heterogeneous and that found in European-style cities, which generally have more homogeneous building heights. It is hypothesized that the greater three-dimensionality caused by the heterogeneous building heights increases the ventilation of the urban canopy through mean advective transport as well as enhanced turbulence.

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23

Shui, Tao Tao, Jing Liu, and Fei Ma. "Numerical Simulation of Cross-Ventilation in Buildings Affected by Surrounding Buildings with Different Separation Distances." Applied Mechanics and Materials 353-356 (August 2013): 2993–96. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.2993.

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In order to investigate natural cross-ventilation in buildings, computational fluid dynamics (CFD) with the DES model is applied. The aim of this paper is to investigate the influence of surrounding buildings on natural ventilation in target building under different separation distances. The simulation results indicate that surrounding buildings has a significant impact on airflow structure and airflow rate of the target building. The flow characteristics in target building is determined by the flow regime in street canyon.

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24

Muhammad Fatih Ibrahim, Mohd Faizal Mohamad, Naoki Ikegaya, and Azli Abd Razak. "Numerical Investigation of Flow and Dispersion over Two-Dimensional Semi-Open Street Canyon." CFD Letters 15, no. 2 (January 20, 2023): 53–70. http://dx.doi.org/10.37934/cfdl.15.2.5370.

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A semi-open street canyon is able to protect pedestrians from unpleasant situations such as direct sunlight and rain. However, the protruding elements of the two opposite building facades that form the semi-open configuration can affect the air quality of the urban canopy layer (UCL). Therefore, this paper investigated the influence of the eave structures on the flow and pollutant dispersion over an idealized 2D street canyon with a unity aspect ratio. The length of the eaves was varied into 0.25H and 0.5H (H is the building height) and placed either on the leeward wall, the windward wall, or on both building facades located at the same elevation as the street canyon. Numerical simulations were performed using the steady-state Reynolds-averaged Navier-Stokes (RANS) equations in conjunction with Re-Normalization Group (RNG) k-ε as the turbulence closure model. The pollutant was released from a line source in the center of the bottom of the target canyon with uniform flow rate. Six different eave configurations were simulated in the wind direction perpendicular to the canyon axis, representing the worst condition of canyon ventilation. The evolution of the primary vortex, which occupied the entire canyon with the characteristic of skimming flow, showed less dependence on the length and position of the eave, except for the longest eave on the windward wall. However, the position of the vortex center depicted opposite results. The pollutant concentration is always higher near the leeward wall, but for the eave that protrudes from the windward wall with a length of 0.5H, the pollutant accumulates near the windward region. The ratio of pollutant concentration showed higher concentration in the semi-open configurations compared to the fully open layout as a result of limited penetration of shear flow into the canyon, which leads to deterioration of pollutant removal.

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25

Fellini, Sofia, Luca Ridolfi, and Pietro Salizzoni. "Street canyon ventilation: Combined effect of cross‐section geometry and wall heating." Quarterly Journal of the Royal Meteorological Society 146, no. 730 (April 21, 2020): 2347–67. http://dx.doi.org/10.1002/qj.3795.

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26

Nazarian, N., and J. Kleissl. "Realistic solar heating in urban areas: Air exchange and street-canyon ventilation." Building and Environment 95 (January 2016): 75–93. http://dx.doi.org/10.1016/j.buildenv.2015.08.021.

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27

Liang, Jie, Liyue Zeng, Shengzhen Zhou, Xuemei Wang, Jiajia Hua, Xuelin Zhang, Zhongli Gu, and Lejian He. "Combined Effects of Photochemical Processes, Pollutant Sources and Urban Configuration on Photochemical Pollutant Concentrations." Sustainability 15, no. 4 (February 10, 2023): 3281. http://dx.doi.org/10.3390/su15043281.

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Анотація:

Rapid urbanization, dense urban configuration and increasing traffic emissions have caused severe air pollution, resulting in severe threats to public health. Particularly, photochemical pollution is associated with chemical transformation introducing more complexity. The understanding of the combined effects of pollutant sources, urban configuration and chemical transformation is still insufficient because most previous studies focused on non-reactive pollutant dispersions. In this study, we adopt a simplified street network model including complex photochemical reactions, i.e., the Model of Urban Network of Intersecting Canyons and Highways (MUNICH), with the real traffic and street data of a region in Guangzhou to investigate the combined effects of the three factors above on photochemical pollution. Our simulations show that the overall reduction in traffic emissions decreases NOx pollution while increasing O3 concentration. Controlling VOC emission can effectively mitigate O3 pollution. Moreover, irregular building heights and arrangements can lead to certain hot spots of air pollution. High-rise buildings will obstruct ventilation and exacerbate pollution. If higher buildings have lower vehicle use, the deep canyon can offset the effect of lower emissions. In conclusion, urban planners and policy makers should avoid deep canyons and irregular street networks to achieve better pollutant dispersion and pay attention to controlling VOC emissions.

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28

Sin, Chung Hyok, Peng-Yi Cui, Yang Luo, Kwang Song Jon, and Yuan-dong Huang. "CFD modeling on the canyon ventilation and pollutant exposure in asymmetric street canyons with continuity/discontinuity balconies." Atmospheric Pollution Research 14, no. 1 (January 2023): 101641. http://dx.doi.org/10.1016/j.apr.2022.101641.

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29

Cheng, W. C., Chun-Ho Liu, and Dennis Y. C. Leung. "Computational formulation for the evaluation of street canyon ventilation and pollutant removal performance." Atmospheric Environment 42, no. 40 (December 2008): 9041–51. http://dx.doi.org/10.1016/j.atmosenv.2008.09.045.

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30

Mei, Shuo-Jun, Zhiwen Luo, Fu-Yun Zhao, and Han-Qing Wang. "Street canyon ventilation and airborne pollutant dispersion: 2-D versus 3-D CFD simulations." Sustainable Cities and Society 50 (October 2019): 101700. http://dx.doi.org/10.1016/j.scs.2019.101700.

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31

Carlos, Jorge S. "Window assessment at different level height on a Portuguese typical street canyon." WEENTECH Proceedings in Energy 4, no. 2 (January 2, 2019): 143–59. http://dx.doi.org/10.32438/wpe.0218.

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This paper presents the results of a study investigating the ventilation mode, the solar heat gain and daylight performance via vertical fenestration on a street canyon. In recent years there has been a growing awareness in energy-efficient building design and operation of the building stock. Dynamic envelope/window systems have potential to optimize the performance of the building, between airing, solar heat gain and daylight admission. However, higher thermal resistance glazing implies a reduction of solar transmittance. A typical street canyon in Portugal was used for the present study. Three different room ratios and two types of windows at two different floors were used for comparison. Different simulation tools were used during this study. To be comparable with other studies several ratios were present, as the window/wall, the glazing/wall ratios, the window/floor and the glazing/floor ratios as well as the window opening area. This paper presents the obtained airflow and solar gains on both heating and cooling season in addition to the level of daylight factor. It was found that specific adaptive actions to improve indoor environmental quality and reduce the need of energy consumption are needed.

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32

Buccolieri, Riccardo, Antoine P. R. Jeanjean, Elisa Gatto, and Roland J. Leigh. "The impact of trees on street ventilation, NOx and PM2.5 concentrations across heights in Marylebone Rd street canyon, central London." Sustainable Cities and Society 41 (August 2018): 227–41. http://dx.doi.org/10.1016/j.scs.2018.05.030.

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33

Ferrari, Simone, Maria Grazia Badas, Michela Garau, Luca Salvadori, Alessandro Seoni, and Giorgio Querzoli. "On The Effect Of The Shape Of Buildings And Chimneystacks On Ventilation And Pollutant Dispersion." EPJ Web of Conferences 213 (2019): 02017. http://dx.doi.org/10.1051/epjconf/201921302017.

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The purpose of this work is to investigate the modifications induced by the change of the roof shape in the flow field, inside and above the buildings, with an attention to their capability to modify the air quality and the dispersion of pollutants released from chimneystacks. We have carried out laboratory experiments on arrays of identical buildings, with symmetrical dual-pitched or flat roofs, and chimneystacks of different heights and positions. The experiments have been carried out in a close-loop water-channel, where two non-intrusive and quasi-continuous in space Digital Image Analysis technique have been implied to measure the velocity fields (Feature Tracking Velocimetry) and the concentration fields (Laser Induced Visualization). Results have highlight the meaningful role of gabled roofs in modifying turbulence, which increases the air exchange rate between the street canyon and the outer flow, but, in some conditions, they increase the dragging of pollutant inside the canyon. These results can have an immediate practical impact on the building design and on planning strategies, as the roof shape can be a useful tool to enhance natural ventilation and pollutant, humidity and/or heat dispersion, i.e. the air quality in urban and industrial areas.

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34

Ai, Z. T., and C. M. Mak. "Wind-induced single-sided natural ventilation in buildings near a long street canyon: CFD evaluation of street configuration and envelope design." Journal of Wind Engineering and Industrial Aerodynamics 172 (January 2018): 96–106. http://dx.doi.org/10.1016/j.jweia.2017.10.024.

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35

Kouklis, Georgios-Rafail, and Athena Yiannakou. "The Contribution of Urban Morphology to the Formation of the Microclimate in Compact Urban Cores: A Study in the City Center of Thessaloniki." Urban Science 5, no. 2 (April 16, 2021): 37. http://dx.doi.org/10.3390/urbansci5020037.

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The purpose of this paper is to investigate the contribution of urban morphology to the formation of microclimatic conditions prevailing within urban outdoor spaces. We studied the compact form of a city and examined, at a detailed, street plan level, elements related to air temperature, urban ventilation, and the individual’s thermal comfort. All elements examined are directly affected by both the urban form and the availability of open and green spaces. The field study took place in a typical compact urban fabric of an old city center, the city center of Thessaloniki, where we investigated the relationship between urban morphology and microclimate. Urban morphology was gauged by examining the detailed street plan, along with the local building patterns. We used a simulation method based on the ENVI-met© software. The findings of the field study highlight the fact that the street layout, the urban canyon, and the open and green spaces in a compact urban form contribute decisively both to the creation of the microclimatic conditions and to the influence of the bioclimatic parameters.

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36

Jon, Kwang Song, Yang Luo, Chung Hyok Sin, Peng-yi Cui, Yuan-dong Huang, and Jun Tokgo. "Impacts of wind direction on the ventilation and pollutant dispersion of 3D street canyon with balconies." Building and Environment 230 (February 2023): 110034. http://dx.doi.org/10.1016/j.buildenv.2023.110034.

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37

Hu, Yun, Yihui Wu, Qun Wang, Jian Hang, Qingman Li, Jie Liang, Hong Ling, and Xuelin Zhang. "Impact of Indoor-Outdoor Temperature Difference on Building Ventilation and Pollutant Dispersion within Urban Communities." Atmosphere 13, no. 1 (December 25, 2021): 28. http://dx.doi.org/10.3390/atmos13010028.

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Mechanical ventilation consumes a huge amount of global energy. Natural ventilation is a crucial solution for reducing energy consumption and enhancing the capacity of atmospheric self-purification. This paper evaluates the impacts of indoor-outdoor temperature differences on building ventilation and indoor-outdoor air pollutant dispersion in urban areas. The Computational Fluid Dynamics (CFD) method is employed to simulate the flow fields in the street canyon and indoor environment. Ventilation conditions of single-side ventilation mode and cross-ventilation mode are investigated. Air change rate, normalized concentration of traffic-related air pollutant (CO), intake fraction and exposure concentration are calculated to for ventilation efficiency investigation and exposure assessment. The results show that cross ventilation increases the air change rate for residential buildings under isothermal conditions. With the indoor-outdoor temperature difference, heating could increase the air change rate of the single-side ventilation mode but restrain the capability of the cross-ventilation mode in part of the floors. Heavier polluted areas appear in the upstream areas of single-side ventilation modes, and the pollutant can diffuse to middle-upper floors in cross-ventilation modes. Cross ventilation mitigates the environmental health stress for the indoor environment when indoor-outdoor temperature difference exits and the personal intake fraction is decreased by about 66% compared to the single-side ventilation. Moreover, the existence of indoor-outdoor temperature differences can clearly decrease the risk of indoor personal exposure under both two natural ventilation modes. The study numerically investigates the building ventilation and pollutant dispersion in the urban community with natural ventilation. The method and the results are helpful references for optimizing the building ventilation plan and improving indoor air quality.

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38

Kwak, Kyung-Hwan, Sung Woo, Kyung Kim, Seung-Bok Lee, Gwi-Nam Bae, Young-Il Ma, Young Sunwoo, and Jong-Jin Baik. "On-Road Air Quality Associated with Traffic Composition and Street-Canyon Ventilation: Mobile Monitoring and CFD Modeling." Atmosphere 9, no. 3 (March 2, 2018): 92. http://dx.doi.org/10.3390/atmos9030092.

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39

Bianch, G. P., and A. L. Braun. "NUMERICAL ANALYSIS OF CIRCULATION AND DISPERSION OF POLLUTANTS IN VENTILATED BUILDINGS UNDER NON-ISOTHERMAL CONDITIONS." Revista de Engenharia Térmica 21, no. 4 (February 6, 2023): 36. http://dx.doi.org/10.5380/reterm.v21i4.89677.

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Air quality, thermal comfort and internal circulation in urban areas are closely linked to the promotion of natural ventilation in buildings. In this sense, the main objectives of the present work are to study the effect of internal circulation in buildings with different openings and the phenomenon of pollutant dispersion in naturally ventilated buildings under non-isothermal conditions using a numerical model for incompressible flows with heat and mass transport. For the flow simulation, a semi-implicit Characteristic-Based Split (CBS) scheme is used in the context of the Finite Element Method (FEM), where linear tetrahedral elements are used for spatial discretization. Turbulence is treated using the Large Eddy Simulation (LES) methodology and thermal effects are considered in the momentum balance equation through buoyancy forces, which are calculated taking into account the Boussinesq approximation. Classical examples are analyzed to verify the numerical model proposed here, as well as the forms of natural ventilation and, finally, a numerical investigation is carried out considering the dispersion of pollutants and the thermal effects simultaneously. In addition to ensuring air exchange while maintaining a healthy environment, ventilation helps to disperse pollutants and promotes thermal comfort, both inside the building and in the street canyon, as indicated by results obtained.

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40

Zhao, Yi, Ruibin Li, Lu Feng, Yan Wu, and Naiping Gao. "Boundary layer wind tunnel tests of outdoor airflow field around urban buildings: A review of methods and status." E3S Web of Conferences 356 (2022): 04031. http://dx.doi.org/10.1051/e3sconf/202235604031.

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Outdoor airflow fields have received increasing attention in the building aerodynamics community due to that the airflow distributions around outdoor buildings are closely related to issues such as thermal comfort, building ventilation, and pollutant dispersion. The focus of this paper is on the airflow distributions around buildings obtained through wind tunnel tests, and such studies are mostly conducted in boundary layer wind tunnel with long test section. This paper reviews current techniques for boundary layer wind tunnel tests of airflow distributions in urban outdoor environments. Then, the characteristics of airflow distributions around buildings in three typical configurations from previous studies (i.e. isolated building, street canyon, and building complexes) are reviewed. This review highlights that the proposed building models should be carefully assessed in combination with wind tunnel tests at the design stage. In addition, it is important to obtain wind tunnel test data for buildings with thermal effects, and the importance of arranging the underlying surfaces during the test is also emphasized.

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41

Wu, Luolin, Jian Hang, Xuemei Wang, Min Shao, and Cheng Gong. "APFoam 1.0: integrated computational fluid dynamics simulation of O3–NOx–volatile organic compound chemistry and pollutant dispersion in a typical street canyon." Geoscientific Model Development 14, no. 7 (July 28, 2021): 4655–81. http://dx.doi.org/10.5194/gmd-14-4655-2021.

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Abstract. Urban air quality issues are closely related to human health and economic development. In order to investigate street-scale flow and air quality, this study developed the atmospheric photolysis calculation framework (APFoam 1.0), an open-source computational fluid dynamics (CFD) code based on OpenFOAM, which can be used to examine microscale reactive pollutant formation and dispersion in an urban area. The chemistry module of APFoam has been modified by adding five new types of reactions, which can implement the atmospheric photochemical mechanism (full O3–NOx–volatile organic compound chemistry) coupled with a CFD model. Additionally, the model, including the photochemical mechanism (CS07A), air flow, and pollutant dispersion, has been validated and shows good agreement with SAPRC modeling and wind tunnel experimental data, indicating that APFoam has sufficient ability to study urban turbulence and pollutant dispersion characteristics. By applying APFoam, O3–NOx–volatile organic compound (VOC) formation processes and dispersion of the reactive pollutants were analyzed in an example of a typical street canyon (aspect ratio H/W=1). The comparison of chemistry mechanisms shows that O3 and NO2 are underestimated, while NO is overestimated if the VOC reactions are not considered in the simulation. Moreover, model sensitivity cases reveal that 82 %–98 % and 75 %–90 % of NO and NO2, respectively, are related to the local vehicle emissions, which is verified as the dominant contributor to local reactive pollutant concentration in contrast to background conditions. In addition, a large amount of NOx emissions, especially NO, is beneficial to the reduction of O3 concentrations since NO consumes O3. Background precursors (NOx/VOCs) from boundary conditions only contribute 2 %–16 % and 12 %–24 % of NO and NO2 concentrations and raise O3 concentrations by 5 %–9 %. Weaker ventilation conditions could lead to the accumulation of NOx and consequently a higher NOx concentration but lower O3 concentration due to the stronger NO titration effect, which would consume O3. Furthermore, in order to reduce the reactive pollutant concentrations under the odd–even license plate policy (reduce 50 % of the total vehicle emissions), vehicle VOC emissions should be reduced by at least another 30 % to effectively lower O3, NO, and NO2 concentrations at the same time. These results indicate that the examination of the precursors (NOx and VOCs) from both traffic emissions and background boundaries is the key point for understanding O3–NOx–VOCs chemistry mechanisms better in street canyons and providing effective guidelines for the control of local street air pollution.

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42

Mullerova, Daniela, and Meredith Williams. "Satellite Monitoring of Thermal Performance in Smart Urban Designs." Remote Sensing 11, no. 19 (September 26, 2019): 2244. http://dx.doi.org/10.3390/rs11192244.

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Climate change amplified by rapidly increasing urbanization is resulting in rising temperatures within urban environments. In recent years, to mitigate this the design and construction of new buildings has emphasized “smart” methods and materials for individual buildings rather than landscape-level planning and evaluation of new developments. Remote Sensing potentially offers a cost-effective means to monitor effectiveness of landscape-level urban design and guide developers to improve thermal regimes. This paper focuses on satellite monitoring of thermal variation in the area of London most affected by construction in 2010–2015. Split-window Land Surface Temperature (LST) models were applied to ASTER and Landsat 8 satellite imagery, requiring separate investigation of thermal trends due to temporal inconsistency. Getis-Ord-Gi* cluster analysis of the ASTER image identified three main thermal hot spots: Eastern, Stratford railway/underground station, and Stratford High Street. It is assumed that increased thermal stress within these areas is mainly from anthropogenic heat. However, local thermal variations for Eastern Olympic Village are attributed to changing meteorological conditions, facade materials, canyon morphology and orientation, or insufficient shading and ventilation. Future development of a new cultural hub at this location will significantly affect distribution of green spaces and influence their cooling ability.

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43

Dai, Yuwei, Fuyao Zhang, and Dongmei Xu. "Experimental analysis of single-sided natural ventilation and interunit dispersion in scaled 2D street canyons." E3S Web of Conferences 356 (2022): 04037. http://dx.doi.org/10.1051/e3sconf/202235604037.

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Interunit dispersion problems have been studied previously mainly through on-site measurements, wind tunnel tests, and CFD simulations. In this study, a scaled outdoor experiment was conducted to examine the interunit dispersion characteristics in consecutive two-dimensional street canyons. Tracer gas (CO2) was continuously released to simulate the pollutant dispersion routes between the rooms in street canyons. The reentry ratio was analyzed to reveal the interunit dispersion of the rooms in the street canyons. This study provides authentic airflow and pollutant dispersion information in the street canyons in an urban environment.

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44

Dall'Osto, M., X. Querol, F. Amato, A. Karanasiou, F. Lucarelli, S. Nava, G. Calzolai, and M. Chiari. "Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site." Atmospheric Chemistry and Physics Discussions 12, no. 8 (August 13, 2012): 20135–80. http://dx.doi.org/10.5194/acpd-12-20135-2012.

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Abstract. Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban Environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter <2.5 μm) resolved Particle Induced X-ray Emission (PIXE) measurements. In the Marie Curie FP7-EU framework of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), the unique approach used is the simultaneous PIXE measurements at two monitoring sites: urban background (UB) and a street canyon traffic road site (RS). Elements related to primary non exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (secondary sulphate (S) – 27%, biomass burning (K) – 5%, sea salt (Na-Mg) – 17%), three types of dust aerosols (soil dust (Al-Ti) – 17%, urban crustal dust (Ca) – 6%, and primary traffic non exhaust brake dust (Fe-Cu) – 7%), and three types industrial aerosol plumes-like events (shipping oil combustion (V-Ni) – 17%, industrial smelters (Zn-Mn) – 3%, and industrial combustion (Pb-Cl) – 5%). The validity of the PMF solution of the PIXE data is supported by strong correlations with external single particle mass spectrometry measurements. Beside apportioning the aerosol sources, some important air quality related conclusions can be drawn about the PM2.5 fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with industrial combustion emissions) is found a to be the major (82%) source of Cl in the urban agglomerate; (4) PM2.5 traffic brake dust (Fe-Cu) is mainly primarily emitted and not resuspended, whereas PM2.5 urban crustal dust (Ca) is found mainly resuspended by both traffic vortex and sea breeze; (5) urban dust (Ca) is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing dust concentrations in road sites, far more effective than street sweeping activities.

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45

Biehl, Jonathan, Bastian Paas, and Otto Klemm. "Ventilation of a Mid-Size City under Stable Boundary Layer Conditions: A Simulation Using the LES Model PALM." Atmosphere 12, no. 3 (March 20, 2021): 401. http://dx.doi.org/10.3390/atmos12030401.

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City centers have to cope with an increasing amount of air pollution. The supply of fresh air is crucial yet difficult to ensure, especially under stable conditions of the atmospheric boundary layer. This case study used the PArallelized Large eddy simulation (LES) Model PALM to investigate the wind field over an urban lake that had once been built as a designated fresh air corridor for the city center of Münster, northwest, Germany. The model initialization was performed using the main wind direction and stable boundary layer conditions as input. The initial wind and temperature profiles included a weak nocturnal low-level jet. By emitting a passive scalar at one point on top of a bridge, the dispersion of fresh air could be traced over the lake’s surface, within street canyons leading to the city center and within the urban boundary layer above. The concept of city ventilation was confirmed in principle, but the air took a direct route from the shore of the lake to the city center above a former river bed and its adjoining streets rather than through the street canyons. According to the dispersion of the passive scalar, half of the city center was supplied with fresh air originating from the lake. PALM proved to be a useful tool to study fresh air corridors under stable boundary layer conditions.

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46

Dall'Osto, M., X. Querol, F. Amato, A. Karanasiou, F. Lucarelli, S. Nava, G. Calzolai, and M. Chiari. "Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS – diurnal variations and PMF receptor modelling." Atmospheric Chemistry and Physics 13, no. 8 (April 26, 2013): 4375–92. http://dx.doi.org/10.5194/acp-13-4375-2013.

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Анотація:

Abstract. Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter < 2.5 μm) resolved aerosol samples analysed by Particle Induced X-ray Emission (PIXE) measurements. In the Marie Curie European Union framework of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), the approach used is the simultaneous sampling at two monitoring sites in Barcelona (Spain) during September–October 2010: an urban background site (UB) and a street canyon traffic road site (RS). Elements related to primary non-exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (regional sulphate (S) – 27%, biomass burning (K) – 5%, sea salt (Na-Mg) – 17%), three types of dust aerosols (soil dust (Al-Ti) – 17%, urban crustal dust (Ca) – 6%, and primary traffic non-exhaust brake dust (Fe-Cu) – 7%), and three types of industrial aerosol plumes-like events (shipping oil combustion (V-Ni) – 17%, industrial smelters (Zn-Mn) – 3%, and industrial combustion (Pb-Cl) – 5%, percentages presented are average source contributions to the total elemental mass measured). The validity of the PMF solution of the PIXE data is supported by very good correlations with external single particle mass spectrometry measurements. Some important conclusions can be drawn about the PM2.5 mass fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with combustion emissions) is found to be the major (82%) source of fine Cl in the urban agglomerate; (4) the mean diurnal variation of PM2.5 primary traffic non-exhaust brake dust (Fe-Cu) suggests that this source is mainly emitted and not resuspended, whereas PM2.5 urban dust (Ca) is found mainly resuspended by both traffic vortex and sea breeze; (5) urban dust (Ca) is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing urban dust concentrations.

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47

Kuo, Chien-Yuan, Rong-Jing Wang, Yi-Pin Lin, and Chi-Ming Lai. "Urban Design with the Wind: Pedestrian-Level Wind Field in the Street Canyons Downstream of Parallel High-Rise Buildings." Energies 13, no. 11 (June 2, 2020): 2827. http://dx.doi.org/10.3390/en13112827.

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We are investigating how to use urban design approaches to conduct the layout and basic design of newly-built high-rise buildings to reduce wind obstruction and create effective urban ventilation. Few studies have addressed this issue. This study analyzes the effects of high-rise building on pedestrian-level wind in downstream street canyons based on wind tunnel test results, and examines the suitability of an urban design specification. The height (H) of high-rise buildings and the airflow passage width (S) between adjacent high-rise buildings are key control factors for this issue; H/D = 3 and S/D = 1.125 are critical parameters and recommended values (D is the height of the downstream street blocks).

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48

Gao, Guo Hua, Jing Liu, Fei Ma, and Wei Dong Luo. "Study on Vehicle Emissions Dispersion in Asymmetrical Street Canyons and Proper Location of Air Intake for Ventilation System." Applied Mechanics and Materials 152-154 (January 2012): 1191–94. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1191.

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Traffic–related pollutant has been recognized as an air pollution hot spot due to its large emission rate and great health impacts for the exposed population. In the present investigation, a computational fluid dynamics technique is used to investigate the effect of street layout on pollutant dispersion and find proper location for air inlet in ventilation systems. Four typical configurations of asymmetric street canyons are considered. It is found that pollutant retention time at people stayed zones is shorter, when buildings near the road are laid as down-wind building lower than the up-wind building. For buildings at down-wind side of a main road, air inlet should be located at the leeward façade of the building.

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49

Yang, Xia, Yong Zhang, Jian Hang, Yuanyuan Lin, Magnus Mattsson, Mats Sandberg, Ming Zhang, and Kai Wang. "Integrated assessment of indoor and outdoor ventilation in street canyons with naturally-ventilated buildings by various ventilation indexes." Building and Environment 169 (February 2020): 106528. http://dx.doi.org/10.1016/j.buildenv.2019.106528.

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50

Ng, Wai Yin, and Chi Kwan Chau. "Evaluating the role of vegetation on the ventilation performance in isolated deep street canyons." International Journal of Environment and Pollution 50, no. 1/2/3/4 (2012): 98. http://dx.doi.org/10.1504/ijep.2012.051184.

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