Ten questions concerning modeling of near-field pollutant dispersion in the built environment

Tominaga, Yoshihide; Stathopoulos, T.

doi:10.1016/j.buildenv.2016.06.027

Cited by 139 publications

(56 citation statements)

References 152 publications

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“…There are two main circumstances that need to be considered in a densely populated city. First, during mild seasons, people may adopt natural ventilation as their main ventilation strategy [5][6][7][8], which may increase the incursion of outdoor pollutants to indoor areas through windows [9]. Second, outbreaks of acutely infectious diseases or even the ordinary flu season [10] may result in airborne viruses or biological aerosols in the airflow, which poses a great threat to public health.…”

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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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: 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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show abstract

“…In addition to the very small sample sizes generally acquired, Tominaga and Stathopoulos [45] observe 'the boundary conditions for field experiments are neither controllable nor repeatable'. They conclude that this constrains their usefulness for supporting systematic or parametric studies, which includes acquiring data against which to assess the performance of AT&D models.…”

Section: Data From Field Experimentsmentioning

confidence: 99%

“…The greatest restriction is in achieving similitude in cases where the thermal and buoyancy effects are significant [45]. This is because it is difficult to vary the stability conditions in a wind tunnel as the creation of thermally stratified flow fields requires heating and/or cooling, so creating and maintaining the desired boundary layer through the working section represents a considerable engineering challenge.…”

Section: Data From Wind Tunnel Experimentsmentioning

confidence: 99%

A Review of Methodology for Evaluating the Performance of Atmospheric Transport and Dispersion Models and Suggested Protocol for Providing More Informative Results

Herring

Huq

2018

Fluids

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Many models exist for predicting the atmospheric transport and dispersion of material following its release into the atmosphere. The purpose of these models may be to support air quality assessments and/or to predict the hazard resulting from releases of harmful materials to inform emergency response actions. In either case it is essential that the user understands the level of predictive accuracy that might be expected. However, contrary to expectation, this is not easily determined from published comparisons of model predictions against data from dispersion experiments. The paper presents and reviews the methods adopted and issues involved in comparing the predictive performance of atmospheric transport and dispersion models to experimental data, by reference to a number of experimental data sets and comparison results. It then presents an approach which is designed to make the performance of atmospheric dispersion models more transparent, through clearly defining the basis on which the comparison is made, and comparing the performance of the chosen model to that of a reference model. Such an approach establishes a clear baseline against which the accuracy of models can be evaluated and the performance benefits of more sophisticated approaches quantified. The use of a simple analytic reference model applicable to continuous ground level releases in open terrain and urban areas is shown as a proof-of-principle.

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“…In general, it has been revealed from the previous studies that in the single-sided ventilation mode, the airflow exchange and migration of contaminants within the building are normally driven by wind effect, buoyancy effect, or combined wind and buoyancy effect. The synoptic wind speed and direction have an essential impact on the strength of wind effect [35,36]. For the buoyancy effect, one inducement is the difference between indoor and outdoor temperature, the other one can be the thermal plume along the high-temperature walls heated by the solar radiation during the daytime, especially in windless or breezy sunny day [37].…”

Section: Introductionmentioning

confidence: 99%

CFD investigation on the effects of wind and thermal wall-flow on pollutant transmission in a high-rise building

Gao

Zhu

2018

Building and Environment

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The solar radiation can heat the building outer surface, and then cause the upward natural convection flows adjacent to the wall. This phenomenon is especially obvious on a windless sunny day. The near wall thermal plume can drive gaseous pollutants released from lower floors to upper floors. Combined with the effect of ambient approaching wind, the transmission routes will be very complicated. The paper aims to investigate the airflow patterns and pollutant transmission within a building under the effects of wind and thermal forces. A hypothetical twenty-storey slab-shape high-rise building in Shanghai with single-sided natural ventilation is set as the research object in the present study. The intensity of solar radiation on a typical day during transition season is theoretically analysed. The temperature difference between the heated building envelope and the ambient air is calculated by a simplified heat balance model. Finally, the tracer gas method is employed in the numerical simulation to analyse the influence of the wind and wall thermal plume flow on the inter-flat pollutant transmission characteristics. The results show that, the temperature difference between sunward and shady side wall is about 10 K at noon on the designate day. When the source is set as a point with steady intensity and the buoyancy is stronger than or approximately equivalent to the wind, the reentry ratio of the flat immediately above the source can be around 25%.

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Ten questions concerning modeling of near-field pollutant dispersion in the built environment

Cited by 139 publications

References 152 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

A Review of Methodology for Evaluating the Performance of Atmospheric Transport and Dispersion Models and Suggested Protocol for Providing More Informative Results

CFD investigation on the effects of wind and thermal wall-flow on pollutant transmission in a high-rise building

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