Direct quadrature method of moments for the exhaust particle formation and evolution in the wake of the studied ground vehicle

Chan, Tat Leung; Liu, Y.H.; Chan, C. K.

doi:10.1016/j.jaerosci.2010.03.005

Cited by 45 publications

(38 citation statements)

References 55 publications

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“…Particle matters from industrial emissions are important sources of atmospheric haze, which transport trajectories are different from internal ones such as automobile exhausts. Numerous researchers have focused on internal source in the urban street (Albriet et al, 2010;Chan et al, 2010;Liu et al, 2011a). However, considerable numbers of people live in industrial areas and are exposed to industrial PM pollutants for prolonged periods.…”

Section: Boundary Conditionsmentioning

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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Section: Boundary Conditionsmentioning

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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“…Different kinds of numerical models have been developed to simulate aerosol dynamic processes including coagulation, nucleation, condensation, etc. [4,5].…”

Section: Introductionmentioning

confidence: 99%

A new differentially weighted operator splitting Monte Carlo method for aerosol dynamics

Liu¹,

Chan²

2016

WIT Transactions on Ecology and the Environment

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Monte Carlo method is a stochastic scheme which replicates the formation, transport and dynamic behaviour of simulation particles with stochastic method. It is based on probabilities rather than solving directly the general dynamic equation. Differentially weighted Monte Carlo method is quite efficient and more practical than using the concept of each simulation particle being equally weighted with a number of real particles. In the present study, a new differentially weighted operator splitting Monte Carlo (DWOSMC) method is developed. In order to increase the computational efficiency of simulating the aerosol processes (i.e., nucleation, coagulation and condensation), an operator splitting technique is used to combine stochastic and deterministic methods. This new DWOSMC method is fully validated through four typical cases considering different aerosol dynamic processes. The results obtained from DWOSMC method agree well with the analytical solutions, which proves very high computational efficiency and accuracy of using DWOSMC method in solving simultaneous aerosol dynamic processes.

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“…The wake of a moving vehicle could significantly enhance particle dispersion, a factor that is absent during idling (Jiang et al 2005;Liu et al 2011). In recent years, some researchers have focused on the dispersion of vehicle exhaust pollutants during idling (Ketzel and Berkowicz 2004;Ning et al 2005;Kinsey et al 2007;McNabola et al 2009;Chan et al 2010). The results show that exhaust pollution concentrations, including gaseous pollutants and particles near the tailpipe, decreased rapidly in the first 2 m from the exhaust; similar conclusions were not drawn under moving vehicle conditions.…”

Section: Introductionmentioning

confidence: 90%

Characteristics of particle coagulation in an underground parking lot

Zhao

Kato

Zhao

2015

Environ Sci Pollut Res

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Particles in vehicle exhaust plumes in underground parking lots have adverse health effects due to the enclosed environment in which they are released and the temperature difference between the tailpipe and ambient environment; at the same time, particle coagulation might be obvious near the tailpipe in an underground parking lot. In the present study, airflow and temperature fields were calculated using the Realizable k-ε model, and the Eulerian particle transport model was selected in the numerical simulation of particle concentration dispersion. Polydisperse thermal coagulation due to Brownian collisions was employed to calculate the particle coagulation. The results show that particle coagulation rate and half-time were significant within 1 m from the tailpipe. The variations in the particle coagulation rate and half-time were similar, but their directions were opposite. Air exhaust time was nearly four times longer than averaged half-time and 40 times longer than minimum half-time. The peak particle diameter increased approximately 1.43 times due to coagulation. A double particle concentration at the tailpipe caused the fourfold rise in the particle coagulation rate in the distance ranging less than 1 m from the tailpipe. An increase in exhaust velocity at the tailpipe could shorten the obvious range of particle coagulation along the centerline of the tailpipe from 1 to 0.8 m in the study.

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Direct quadrature method of moments for the exhaust particle formation and evolution in the wake of the studied ground vehicle

Cited by 45 publications

References 55 publications

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

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

A new differentially weighted operator splitting Monte Carlo method for aerosol dynamics

Characteristics of particle coagulation in an underground parking lot

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