Dry deposition model for a microscale aerosol dispersion solver based on the moment method

Abstract

A dry deposition model suitable for use in the moment method has been developed. Contributions from five main processes driving the deposition -Brownian diffusion, interception, impaction, turbulent impaction, and sedimentation -are included in the model. The deposition model was employed in the moment method solver implemented in the OpenFOAM framework. Applicability of the developed expression and the moment method solver was tested on two example problems of particle dispersion in the presence of a vegetation on small scales: a flow through a tree patch in 2D and a flow through a hedgerow in 3D. Comparison with the sectional method showed that the moment method using the developed deposition model is able to reproduce the shape of the particle size distribution well. The relative difference in terms of the third moment of the distribution was below 10% in both tested cases, and decreased away from the vegetation. Main source of this difference is a known overprediction of the impaction efficiency. When tested on the 3D test case, the moment method achieved approximately eightfold acceleration compared to the sectional method using 41 bins.

Atmospheric Dry Deposition to Natural Water of Wetland in Suburban Beijing

“…A number of previous studies have concluded that wetlands can reduce particulate matter to some extent via the increase in relative humidity within a certain range [40,41]. Previous studies have indicated that wind direction affects dry deposition [42,43], while in this study, the main wind blew from SE during daytime and nighttime, and other wind directions were rarely recorded.…”

User’s Manual for RESRAD-BUILD Code V.4: Vol. 1 – Methodology and Models Used in RESRAD-BUILD Code

“…The deposition velocity is minimal at a particle size below one micron. (Šíp and Beneš 2017) The deposition velocity, considering these processes, is about 4E-4 m/s at one micron. Since this is close to the mean value of uncertainty distribution, the mean (3.9E-4 m/s) is set as the default deposition velocity in RESRAD-BUILD.…”

Monte Carlo simulation of polydisperse particle deposition and coagulation dynamics in enclosed chambers

“…The particle dynamical mechanisms can be quite complicated in different applications. For example the deposition mechanisms include Brownian diffusion, gravitational sedimentation, turbulent impaction, interception and inertial impaction, wet removal and so on [1,12]; the coagulation mechanisms include Brownian diffusion, turbulent diffusion, thermal motion, electrical charges, preferential concentration and so on [13]. In different regimes, the mechanisms and importance of deposition and coagulation will be different.…”