Deposition of non-spherical particles on indoor surfaces: Modification of diffusion coefficient

Abstract

Although there have been studies on gravitational settling of non-spherical particles, only few studies have incorporated the diffusion of non-spherical particles into particle deposition. Non-spherical particles occupy a large proportion of particles in indoor environments, and their deposition is a key factor that influences the level of indoor particulate matter pollution. In this study, we modified drag coefficient and diffusion coefficient based on settling experiment and Langevin equation to fulfill a semi-analytical modeling of particle deposition on indoor surfaces. The modified diffusion coefficient and deposition velocity agree well with the experimental results for fibers. With the modified diffusion coefficient, we further modeled the deposition of non-spherical particles on indoor surfaces under typical air friction velocity conditions. The results showed that the deposition velocity between spherical and non-spherical particle deviated by 10–25% with the same aerodynamic diameter for diffusion-controlled region, while the application of aerodynamic diameter would lead to 10% to over 100% deviation with 10 $\mu m$ particle for particle depositing on side walls. However, the deposition of non-spherical particle can be estimated rightly through spherical particle with the same aerodynamic diameter when gravitational settling dominates the deposition process. The modification of the diffusion coefficient and deposition velocity of non-spherical particles is expected to help in understanding the effect of particle shape on its deposition and may be further applied to indoor particle pollution modeling.

Copyright © 2022 American Association for Aerosol Research

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Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (No. 51978366).