Application of the k–ε turbulence model to the high Reynolds number skimming flow field of an urban street canyon

Jeong, Sang Jin; Andrews, Malcolm J.

doi:10.1016/s1352-2310(01)00569-6

Cited by 91 publications

(43 citation statements)

References 11 publications

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“…While the velocity magnitude for AR 1.33 is similar to that seen for AR 1, it drastically drops for AR 2 and 4, indicating that the multivortex ow is characterized by very poor ventilation, particularly at the street level. e results presented above conform to those presented in [9,58,61,[65][66][67]71], which simulated canopy ows through CFD, employing di erent turbulence models.…”

Section: E Ect Of Aspect Ratio Variationssupporting

confidence: 80%

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: E Ect Of Aspect Ratio Variationssupporting

confidence: 80%

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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“…It is interesting to note that, in their numerical studies using a k − ε model, Chan et al (2002) and Jeong and Andrews (2002) identified two and three primary recirculations in the street canyon of AR = 3, respectively. The reason for this difference lies in the fact that the current LES and the study of Jeong and Andrews (2002) investigated urban street canyons (among a group of buildings), while the street canyon studied in Chan et al (2002) is isolated (in open country).…”

Section: Characteristics Of the Flow Fieldmentioning

confidence: 99%

Large-Eddy Simulation of Flow and Pollutant Dispersion in High-Aspect-Ratio Urban Street Canyons with Wall Model

Liu

Leung

2008

Boundary-Layer Meteorol

101

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A large-eddy simulation (LES) with a one-equation subgrid-scale (SGS) model was developed to investigate the flow field and pollutant dispersion inside street canyons of high aspect ratio (AR). A 1/7th power-law wall model was implemented near rigid walls to mitigate the demanding near-wall resolution requirements in LES. This LES model had been extensively validated against experimental results for street canyons of AR = 1 and 2 before it was applied to the cases of AR = 3 and 5. A ground-level passive pollutant line source, located in the middle of the street, was used to simulate vehicular emissions. Three and five vertically aligned primary recirculations were developed in the street canyons of AR 3 and 5, respectively. The ground-level mean wind speed was less than 0.5% of the free stream value, which makes it difficult for the pollutant to be transported upward for removal. High pollutant concentration and variance were found near the buildings where the air flow is upwards. It was found that the velocity fluctuation, pollutant concentration and variance were all closely related to the interactions between the primary recirculations and/or the free surface layer. Several quantities, which are non-linear functions of AR, were introduced to quantify the air quality in street canyons of different configurations.

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“…Experimental data has been obtained both from field studies (Rotach, 1995;Costabile and Allegrini, 2007) and from wind-tunnel (Pavageau and Schatzmann, 1999) and water tank models (Caton et al, 2003). Computational modelling has been carried out in order to investigate the fluid mechanics and the dispersion of pollutants in and around the canyon (Chan et al, 2001;Baik and Kim, 2002;Jeong and Andrews, 2002). Work has also been carried out which attempts to quantify the exchange of mass and momentum at rooftop level using an exchange velocity in order to provide a model that can be applied to a real-world situations (Hamlyn and Britter, 2005).…”

Section: Introductionmentioning

confidence: 99%

Simulations of the dispersion of reactive pollutants in a street canyon, considering different chemical mechanisms and micromixing

Garmory

Kim

Britter

et al. 2009

Atmospheric Environment

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Application of the k–ε turbulence model to the high Reynolds number skimming flow field of an urban street canyon

Cited by 91 publications

References 11 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

Large-Eddy Simulation of Flow and Pollutant Dispersion in High-Aspect-Ratio Urban Street Canyons with Wall Model

Simulations of the dispersion of reactive pollutants in a street canyon, considering different chemical mechanisms and micromixing

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