CFD simulation of the effect of an upstream building on the inter-unit dispersion in a multi-story building in two wind directions

Cui, Dongjin; Mak, Cheuk Ming; Kwok, K.C.S.; Ai, Zhengtao

doi:10.1016/j.jweia.2016.01.007

Cited by 42 publications

(40 citation statements)

References 27 publications

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“…With a strong vortex, the tracer gas transportation routes were established when the source location was fixed. The tracer transportation characteristics in the street canyon had large differences from the conditions of an isolated building [4,23,24] or building arrays [25,26]. Without lateral separation flows, the tracer gas will disperse from the top of the street canyon or spread horizontally inside the street canyon.…”

Section: Interunit Dispersion Of Building Bmentioning

confidence: 99%

“…A series of numerical studies were conducted to further understand the influential factors of interunit dispersion, including the effects of buoyancy-dominated forces [15,[20][21][22], balconies [10,23,24], surrounding interfering buildings [25,26], and heated walls [27]. Different turbulence models were considered in the airflow and dispersion simulations, including a mean process with an advanced Reynolds-Averaged Navier-Stokes (RANS) model [10,23,25,26] and transient process with an Large-Eddy Simulation (LES) model [24,28]. However, the wind tunnel experiments and CFD simulations were based on assumed atmospheric boundary conditions, which do not consider realistic factors of the urban environment.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of interunit dispersion in 2D street canyons: A scaled outdoor experiment

Dai

Mak

Zhang

et al. 2020

Building and Environment

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A B S T R A C TInterunit 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 (CO 2 ) was continuously released to simulate the pollutant dispersion routes between the rooms in street canyons. The wind velocity, wind direction, air temperature, and tracer gas concentrations were monitored simultaneously. Two important parameters, the air exchange rate and reentry ratio, were analyzed to reveal the ventilation performance and interunit dispersion of the rooms in the street canyons. Based on the real-time weather conditions, it was found that the ventilation performance of the source room varied according to the room location. The air exchange rate distribution of the leeward-side room was more stable than that of the windward side. The tracer gas was mainly transported in the vortex direction inside the street canyon, and the highest reentry ratio was observed at the room nearest to the source room along the transportation route. In addition, under real weather conditions, the rooms in the street canyon have a high probability of experiencing a high reentry ratio based on the maximum reentry ratio of each room. This study provides authentic airflow and pollutant dispersion information in the street canyons in an urban environment. The dataset of this experiment can be used to validate further numerical simulations.

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Section: Interunit Dispersion Of Building Bmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of interunit dispersion in 2D street canyons: A scaled outdoor experiment

Dai

Mak

Zhang

et al. 2020

Building and Environment

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“…Many of these studies emerged from the SARS threat. Examples are the studies by , Niu and Tung (2008), Gao et al (2008), Ai et al (2013), Ai and Mak (2014, 2015a, 2015b and Cui et al (2016). Two review papers on the topic of inter-unit dispersion by single-sided natural ventilation were provided by Mak (2015a, 2015b) and Mao and Gao (2015).…”

Section: Introductionmentioning

confidence: 99%

Wind tunnel analysis of flow and dispersion in cross-ventilated isolated buildings: Impact of opening positions

Tominaga

Blocken

2016

Journal of Wind Engineering and Industrial Aerodynamics

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a b s t r a c tThis paper presents a detailed experimental analysis of flow and dispersion by cross-ventilation in five generic isolated single-zone buildings with different opening positions. First, flow visualization is performed illustrating the highly transient flow and dispersion process dominated by a flapping jet with pronounced Kelvin-Helmholtz instabilities. Next, the mean velocity field, the turbulent kinetic energy field, the mean concentration field and the concentration fluctuation field are presented and analyzed. Finally, time histories of the instantaneous concentration in the building are provided. The contaminant dispersion in the cross-ventilated flow is strongly influenced by the overall flow pattern that is largely determined by the inlet opening position, while the outlet opening position seems less important. The results provide new insights in the flow and dispersion process inside cross-ventilated buildings and can be used to validate Computational Fluid Dynamics (CFD) simulations of flow and dispersion by crossventilation and for the subsequent establishment of new CFD best practice guidelines. It is also shown that the use of different ventilation performance parameters yields a different ranking of the configurations in terms of ventilation performance. Care should therefore be applied when evaluating ventilation performance based on only flow rates or velocities as opposed to dispersion quantities.

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“…Compared with large eddy simulation and detached eddy simulation models, the RANS-based modeling approach significantly reduces the required computational power and resources [34,37]. Several studies have successfully employed RANS models to predict indoor and outdoor airflows in windward and leeward conditions [23,39]. The baseline k-ω turbulence model, which is a two-equation eddy-viscosity model, was also found to yield satisfactory accuracy and stability when modeling an indoor airflow [40].…”

Section: Numerical Modelmentioning

confidence: 99%

Numerical investigation of gaseous pollutant cross-transmission for single-sided natural ventilation driven by buoyancy and wind

Wang

Huo

Zhang

et al. 2020

Building and Environment

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A B S T R A C TSingle-sided natural ventilation was numerically investigated to determine the impact of buoyancy and wind on the cross-transmission of pollution by considering six window types commonly found in multistory buildings. The goal of this study was to predict the gaseous pollutant transmission using computational fluid dynamics based on the Reynolds-averaged Navier-Stokes equations and baseline k-ω turbulence equations. The results indicated that ventilation rates generally increased with increasing wind speeds if the effects of buoyancy and wind were not suppressed; however, the re-entry ratio representing the proportion of expelled air re-entering other floors and the corresponding risk of infection decreased. If the source of the virus was on a central floor, the risk of infection was the highest on the floors closest to the source. Different window types were also considered for determining their effectiveness in controlling cross-transmission and infection risk, depending on the source location and driving force (e.g., buoyancy and wind).

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CFD simulation of the effect of an upstream building on the inter-unit dispersion in a multi-story building in two wind directions

Cited by 42 publications

References 27 publications

Investigation of interunit dispersion in 2D street canyons: A scaled outdoor experiment

Investigation of interunit dispersion in 2D street canyons: A scaled outdoor experiment

Wind tunnel analysis of flow and dispersion in cross-ventilated isolated buildings: Impact of opening positions

Numerical investigation of gaseous pollutant cross-transmission for single-sided natural ventilation driven by buoyancy and wind

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