Transport mechanisms of airborne particulate matters in partitioned indoor environment

Chang, Tsang‐Jung; Hu, Ting-Shing

doi:10.1016/j.buildenv.2007.01.030

Cited by 58 publications

(26 citation statements)

References 16 publications

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“…Herein, deposition and escape are regarded as the particle removal mechanisms. 32 The above deposition mechanism represents the combined results of inertial impaction, turbulence-eddy impaction, interception, gravitational sedimentation, and the Brownian motion, which can be thoroughly simulated by the present numerical model. Table 2 demonstrates the cumulative mass fractions of particle escape, wall deposition, ground deposition, and roof deposition for both of the street canopies.…”

Section: Pm 10 Transport Mechanismsmentioning

confidence: 99%

Transport Mechanisms of Coarse, Fine, and Very Fine Particulate Matter in Urban Street Canopies with Different Building Layouts

Chang

Kao

et al. 2009

Journal of the Air & Waste Management Association

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A particulate matter (PM) transport model is developed to investigate coarse PM (PM 10 ), fine PM (PM 2.5 ), and very fine PM (PM 1 ) transport mechanisms in urban street canopies under low-wind conditions. Two common building layouts (i.e., the open and staggered street canopies) are considered. Large eddy simulations with the subgrid-scale stress model and the wall function are used to simulate urban streetcanopy flows. The Lagrangian particle tracking approach, considering the effects of the drag force, gravitational force, Brownian motion, and Saffman lift force on particles is adopted to study PM transport behaviors in urban street canopies. The box counting method is used to calculate the canopy-averaged PM 10 /PM 2.5 /PM 1 mass concentrations and transport mechanisms at each tracking time. The simulated results show that the removal efficiencies of PM 10 , PM 2.5 , and PM 1 in the open street canopies are all better than those in the staggered street canopies. As a result, the open street canopies having higher PM removal ability lead to a swifter shift of the particle size distributions towards smaller size and less deviation than the staggered street canopies. The major particle removal mechanism for the open street canopies is particle escape, whereas wall deposition plays the most important role for the staggered street canopies. In comparison with the effectiveness of PM 10 /PM 2.5 /PM 1 removal for both building layouts, PM 10 particles are easier to overcome the root mean square vertical turbulent velocity and need less time to deposit. Fine particles would follow airflow paths and need longer time to deposit. As a result, PM 2.5 and PM 1 are more difficult to be removed than PM 10 .

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Section: Pm 10 Transport Mechanismsmentioning

confidence: 99%

Transport Mechanisms of Coarse, Fine, and Very Fine Particulate Matter in Urban Street Canopies with Different Building Layouts

Chang

Kao

et al. 2009

Journal of the Air & Waste Management Association

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“…For the diffusion of bioaerosols in the laboratory, a one-way coupling Lagrangian method is employed to track spherical particles. There are several major particle driving forces to consider when calculating the motion of suspended particles [ 23 ]. Previous studies [ 24 , 25 ] indicated that the driving forces of small-sized particles such as pressure gradient force, Magnus force and virtual mass force are lower in magnitude than other forces and therefore not adopted in this study.…”

Section: Methodsmentioning

confidence: 99%

Effect of equipment layout on bioaerosol temporal-spatial distribution and deposition in one BSL-3 laboratory

Liu

Zhuang

et al. 2020

Building and Environment

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Reasonable equipment layout is essential for creating a healthy and safe environment, especially in a three-level biosafety laboratory with high potential risk factors of infection. Since 2019, COVID-19, an emerging infection has swept the world and caused severe losses. Biosafety laboratories are mandatory sites for detecting high-risk viruses, so related research is urgently needed to prevent further laboratory-acquired infections of operators. This study investigated the effects of obstacles on exposure infection of staff in a biosafety laboratory with related experimental equipment. The numerical simulation results are highly verified by the measured results. The results indicate that although the equipment layout does not affect the bioaerosol removal time, nearly 17% of the pollutant particles in the actual laboratory cannot be discharged effectively compared with the ideal situation. These particles lingered in the lower space under the influence of vortex, which would increase the respiratory risk of operators. In addition, after the experiment a large part of bioaerosol particles would be captured by equipment and floor, and the deposition rate per unit area is 0.45%/m 2 and 0.8%/m 2 , respectively. Although the results show that the equipment layout could reduce the pollution on the floor, the disinfection is still an important link, especially on the surfaces of equipment. Meanwhile, the result also indicates that the action should be light and slow when operating in BSL-3 laboratory, so as to avoid the secondary suspension pollution of bioaerosol particles on the equipment surface and floor.

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“…44 The SST model is a blended k-ε/k-ω model proposed by Menter, 45 which predicts free stream turbulence quantities with the k-ε model and predicts more accurately boundary layer separation flows in adverse pressure gradients with the k-ω model. 46 The commercial CFD code ANSYS-Fluent was used for the modelling and the discretization involved the QUICK scheme for momentum, and the SIMPLE algorithm for pressure–velocity coupling. The second-order upwind scheme was used for the convection and diffusion terms.…”

Section: Methodsmentioning

confidence: 99%

Computational fluid dynamics study of human-induced wake and particle dispersion in indoor environment

Tao

Inthavong

2016

Indoor and Built Environment

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The impact of human-induced wake flow and particle re-dispersion from floors in an indoor environment was investigated by performing computational fluid dynamics simulations with dynamic mesh of a moving manikin model in a confined room. The manikin motion was achieved by a dynamic layering mesh method to update new grids with each time step. Particle transport from the floors and its redispersion was tracked by a Lagrangian approach. A series of numerical simulations of three walking speeds were performed to compare the flow disturbance induced by the walking motion. The significant airflow patterns included: an upward-directed flow in front of the body combined with a high velocity downward-directed flow at the rear of the body; a stagnant region behind the gap between the legs and counter-rotating vortices in the wake region. The airflow momentum induced by the moving body disturbed PM 2.5 particles that were initially at rest on the floor to lift and become re-suspended due to its interaction with the trailing wake. The residual flow disturbances after the manikin stopped moving continued to induce the particle to spread and deposit over time. The spatial and temporal characteristics of the particle dispersion and concentration showed that higher walking speed was conducive to reducing human's exposure to contaminants in breathing region.

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Transport mechanisms of airborne particulate matters in partitioned indoor environment

Cited by 58 publications

References 16 publications

Transport Mechanisms of Coarse, Fine, and Very Fine Particulate Matter in Urban Street Canopies with Different Building Layouts

Transport Mechanisms of Coarse, Fine, and Very Fine Particulate Matter in Urban Street Canopies with Different Building Layouts

Effect of equipment layout on bioaerosol temporal-spatial distribution and deposition in one BSL-3 laboratory

Computational fluid dynamics study of human-induced wake and particle dispersion in indoor environment

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