Influence of Geometry on the Mean Flow within Urban Street Canyons — A Comparison of Wind Tunnel Experiments and Numerical Simulations

Kovar-Panskus, A.; Louka, P.; Sini, J.-F.; Savory, Eric; Czech, Michael; Abdelqari, A.; Mestayer, P.G.; Toy, N.

doi:10.1007/978-94-010-0312-4_26

Cited by 31 publications

(67 citation statements)

References 15 publications

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“…At AR 0.5, indeed, it shows two adjacent vortices: the downstream one is by far the larger and rotates clockwise, while the upstream one is smaller, occupying nearly 1/4 of the canyon and rotates counterclockwise. is pattern is in agreement with experimental data and numerical simulations performed in [9,60,61,[63][64][65].…”

Section: Turbulence Model Evaluationsupporting

confidence: 90%

“…For AR 1, the CFD simulates also a counterclockwise recirculating region located in the upper part of the facet of the leeward building and other two smaller vortices, located at the bottom corners. ese data also match other results reported in the literature [60][61][62][63][64]. Both measurements and simulations show that the size of the secondary vortex located at the bottom of the leeward building grows with AR.…”

Section: Turbulence Model Evaluationsupporting

confidence: 89%

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CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights

Nardecchia

Bernardino

Pagliaro

et al. 2018

Advances in Meteorology

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Computational fluid dynamics (CFD) is currently used in the environmental field to simulate flow and dispersion of pollutants around buildings. However, the closure assumptions of the turbulence usually employed in CFD codes are not always physically based and adequate for all the flow regimes relating to practical applications. e starting point of this work is the performance assessment of the V2F (i.e., v 2 − f ) model implemented in Ansys Fluent for simulating the flow field in an idealized array of twodimensional canyons. e V2F model has been used in the past to predict low-speed and wall-bounded flows, but it has never been used to simulate airflows in urban street canyons. e numerical results are validated against experimental data collected in the water channel and compared with other turbulence models incorporated in Ansys Fluent (i.e., variations of both k-ε and k-ω models and the Reynolds stress model). e results show that the V2F model provides the best prediction of the flow field for two flow regimes commonly found in urban canopies. e V2F model is also employed to quantify the air-exchange rate (ACH) for a series of two-dimensional building arrangements, such as step-up and step-down configurations, having different aspect ratios and relative heights of the buildings. e results show a clear dependence of the ACH on the latter two parameters and highlight the role played by the turbulence in the exchange of air mass, particularly important for the step-down configurations, when the ventilation associated with the mean flow is generally poor.

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Section: Turbulence Model Evaluationsupporting

confidence: 90%

Section: Turbulence Model Evaluationsupporting

confidence: 89%

CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights

Nardecchia

Bernardino

Pagliaro

et al. 2018

Advances in Meteorology

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“…Many studies focussed on investigations of circulation (e.g., DePaul and Sheih, 1986;Kovar-Panskus et al, 2002;Cheng and Hu, 2004;Lien et al, 2004) and dispersion of pollutants inside street canyons (e.g., Ketzel et al, 2002;Baik and Kim, 2002;Kim and Baik, 2004;Xie et al, 2005;Nazridoust and Ahmadi, 2006). When the wind flow is perpendicular to the street, a recirculation vortex develops.…”

Section: Introductionmentioning

confidence: 99%

Correlation between traffic density and particle size distribution in a street canyon and the dependence on wind direction

et al. 2006

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Abstract. Combustion of fossil fuel in gasoline and diesel powered vehicles is a major source of aerosol particles in a city. In a street canyon, the number concentration of particles smaller than 300 nm in diameter, which can be inhaled and cause serious health effects, is dominated by particles originating from this source.In this study we measured both, particle number size distribution and traffic density continuously in a characteristic street canyon in Germany for a time period of 6 months. The street canyon with multistory buildings and 4 traffic lanes is very typical for larger cities. Thus, the measurements also are representative for many other street canyons in Europe. In contrast to previous studies, we measured and analyzed the particle number size distribution with high size resolution using a Twin Differential Mobility Analyzer (TDMPS). The measured size range was from 3 to 800 nm, separated into 40 size channels.Correlation coefficients between particle number concentration for integrated size ranges and traffic counts of 0.5 were determined. Correlations were also calculated for each of the 40 size channels of the DMPS system, respectively. We found a maximum of the correlation coefficients for nucleation mode particles in the size range between 10 and 20 nm in diameter.Furthermore, correlations between traffic and particles in dependence of meteorological data were calculated. Relevant parameters were identified by a multiple regression method. In our experiment only wind parameters have influenced the particle number concentration significantly. High correlation coefficients (up to 0.8) could be observed in the lee side of the street canyon for particles in the range between 10 and 100 nm in diameter. These values are significantly higher than correlation coefficients for other wind directions and other particle sizes. A minimum was found in the luff Correspondence to: J. Voigtländer (jensv@tropos.de) side of the street. These findings are in good agreement with theory of fluid dynamics in street canyons.

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“…Such examples as: freestanding solids [13][14][15][16], regular alignment of solids [3,17], the space between the two walls showing the street model [18], are often referred. However publications concerning more complex geometric structures, which take into account the surrounding development and as such are closer to the real problems met in architectural design, are relatively rare [5,19,20].…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of numerical and experimental studies of the airflow around the sample of urban development

Gumowski

Olszewski

Poćwierz

et al. 2015

Bulletin of the Polish Academy of Sciences Technical Sciences

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Abstract. In this paper, on the background of a short overview of the recent advances in the field of Environmental Wind Engineering (EWE), a comparison of wind tunnel experiment and numerical simulation for some cases of airflow around an urban layout have been reported. The purpose of the study is quantitative and qualitative comparison of measurements in the wind tunnel as well as numerical simulation using Ansys Fluent software. The study is concerned mostly with the analysis of parameters which are essential in the building industry, such as pressure and velocity fields. In the numerical analysis the k-ε realizable model of turbulence with the basic model of boundary layer -Standard Wall Treatment, were used. Particular attention has been paid to accurate depiction of the conditions on the inlet and the selection of suitable computing.

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Influence of Geometry on the Mean Flow within Urban Street Canyons — A Comparison of Wind Tunnel Experiments and Numerical Simulations

Cited by 31 publications

References 15 publications

CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights

CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights

Correlation between traffic density and particle size distribution in a street canyon and the dependence on wind direction

Comparative analysis of numerical and experimental studies of the airflow around the sample of urban development

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