Large eddy simulation of wind field and pollutant dispersion in downtown Macao

Liu, Y.S.; Cui, Guixiang; Wang, Z.S.; Zhang, Z.S.

doi:10.1016/j.atmosenv.2011.03.001

Cited by 50 publications

(20 citation statements)

References 21 publications

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“…In several studies, CFD has been applied to pollutant dispersion around actual building groups in urban areas based on RANS (Moon et al, 1997;Hanna et al, 2006;Tseng et al, 2006;Patnaik et al, 2007;Neofytou et al, 2008;Baik et al, 2009;Zhang et al, 2009;Pontiggia et al, 2010Pontiggia et al, , 2011 and LES (Xie and Castro, 2009;Xie, 2011;Liu et al, 2011). Although reasonable qualitative outcomes have been obtained from these studies, the results must be evaluated quantitatively.…”

Section: Dispersion Around Building Complexesmentioning

confidence: 98%

CFD simulation of near-field pollutant dispersion in the urban environment: A review of current modeling techniques

Tominaga

Stathopoulos

2013

Atmospheric Environment

404

158

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h i g h l i g h t s CFD simulations of near-field dispersion in the urban environment are reviewed. Key features of near-field pollutant dispersion are identified and discussed. To understand inherent strengths and limitations of numerical models is important. Careful model evaluation while paying attention to their uncertainty is necessary. a b s t r a c tNear-field pollutant dispersion in the urban environment involves the interaction of a plume and the flow field perturbed by building obstacles. In the past two decades, micro-scale Computational Fluid Dynamics (CFD) simulation of pollutant dispersion around buildings and in urban areas has been widely used, sometimes in lieu of wind tunnel testing. This paper reviews current modeling techniques in CFD simulation of near-field pollutant dispersion in urban environments and discusses the findings to give insight into future applications. Key features of near-field pollutant dispersion around buildings from previous studies, i.e., three-dimensionality of mean flow, unsteadiness of large-scale flow structure, and anisotropy of turbulent scalar fluxes, are identified and discussed. This review highlights that it is important to choose appropriate numerical models and boundary conditions by understanding their inherent strengths and limitations. Furthermore, the importance of model evaluation was emphasized. Because pollutant concentrations around buildings can vary by orders of magnitudes in time and space, the model evaluation should be performed carefully, while paying attention to their uncertainty. Although CFD has significant potential, it is important to understand the underlying theory and limitations of a model in order to appropriately investigate the dispersion phenomena in question.

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Section: Dispersion Around Building Complexesmentioning

confidence: 98%

CFD simulation of near-field pollutant dispersion in the urban environment: A review of current modeling techniques

Tominaga

Stathopoulos

2013

Atmospheric Environment

404

158

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“…Some researchers modeled and predicted the pollutant diffusion in actual urban three-dimensional areas such as London (Xie and Castro, 2009), Montreal (Gousseau et al, 2011), Macao (Liu et al, 2011b). In order to clarify the effect of the street structure, weather conditions and other flow boundary conditions on the diffusion of pollutants, it was necessary to simplify the real street arrangement to ensure the general applicability of the research results.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Airflow and Particle Dispersion in Street Canyons under Unsteady Thermal Environment with Sinusoidal Variation

Mercola

Wang

Deng

2017

Aerosol Air Qual. Res.

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Unstable temperature stratification conditions have a considerable influence on pollutant diffusion inside street canyons. In this study, we tried to model the air flow and particle dispersion in street canyons under unsteady thermal environment. The sinusoidal variation was used to model the atmosphere temperature on the basis of the solar radiation cycle that occurs over a day. The two-dimensional model of step-up building layouts was applied as the research object and an RNG turbulence model was applied to study the dynamic characteristics of instantaneous airflow, the dimensionless air exchange rate (ACH) and turbulent kinetic energy (TKE) in the different canyons. A series of numerical simulations were performed for different Richardson numbers (Ri). The results demonstrated that the stream function within the street canyons exhibited a periodic shift over a day, and the flow morphology gradually evolved from paralleled bilateral vortexes into a row of vortexes, particularly when the ground temperature increased. Moreover, the local PM concentrations at different times were obtained, and they were affected by the flow field patterns. The total PM mass in the street canyon decreased as the air velocity increased. Furthermore, the dimensionless ACH and TKE exhibit a noticeable fluctuation with time at higher Ri and stronger buoyancy. As the Ri decreases, the enhanced forced convection causes the ACH and TKE to remain constant over time. From these results, inhabitants should be advised to adopt preventative measures aimed at the PM pollution according to the time and location where they live.

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“…The main advantage of CFD simulation is its ability to provide simultaneous data on both wind speed and flow circulation at the pedestrian level, avoiding the hassle of the two-step approach common in wind-tunnel tests [18]. CFD simulations also have proven accuracy in simulating PLW fields around isolated buildings [19][20][21], around arrays of buildings [22][23][24], in idealized city models [25][26][27], and in real urban areas [28][29][30]. All these studies highlighted the importance of proper inflow conditions for accurate results from CFD simulations.…”

Section: Introductionmentioning

confidence: 99%

New inflow boundary conditions for modeling twisted wind profiles in CFD simulation for evaluating the pedestrian-level wind field near an isolated building

Weerasuriya

Zhang

et al. 2018

Building and Environment

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The hilly topography of Hong Kong influences oncoming winds and gradually changes their wind directions along the profiles' height. The vertical variation in wind directions, or the twist effect, significantly influences the Pedestrian Level Wind (PLW) field in urban areas of Hong Kong, thus it is a topic demanding systematic investigations. In this study, a new set of inflow boundary conditions are proposed to model twisted wind flows in Computational Fluid Dynamic (CFD) simulations. The new inflow boundary condition derived based on the horizontal homogeneous assumption, specifies a vertical profile of lateral wind speeds at the inlet boundary to sustain the twist effect in the empty computational domain. The proposed boundary conditions are used to simulate the PLW fields near three isolated buildings with different Height-to-Width ratio using two CFD codes; OpenFOAM, and FLUENT. The results reveal that OpenFOAM is more reliable in simulating PLW fields in twisted wind flows using the new set of boundary conditions. The three-dimensional flow field provided by the OpenFOAM simulation shows sparse streamlines downstream the buildings, indicating lack of organized eddies in the building far wake, which negatively affects the dispersion of air pollutants in twisted winds.

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Large eddy simulation of wind field and pollutant dispersion in downtown Macao

Cited by 50 publications

References 21 publications

CFD simulation of near-field pollutant dispersion in the urban environment: A review of current modeling techniques

CFD simulation of near-field pollutant dispersion in the urban environment: A review of current modeling techniques

Modeling the Airflow and Particle Dispersion in Street Canyons under Unsteady Thermal Environment with Sinusoidal Variation

New inflow boundary conditions for modeling twisted wind profiles in CFD simulation for evaluating the pedestrian-level wind field near an isolated building

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