Adhesion and aerodynamic forces for the resuspension of non-spherical particles in outdoor environments. (October 2017)

• Record Type: Journal Article
• Authors: Brambilla, Sara; Speckart, Scott; Brown, Michael J.
• Is Part Of: Journal of aerosol science. Volume 112(2017)
• Page Start: 52
• Page End: 67
• Publication Date: 2017-10
• Subjects: Colloidal rod-shaped particles -- Particle adhesion -- Surface forces -- Aerodynamic forces; Aerosols -- Periodicals; Aerosols -- Periodicals; Aérosols -- Périodiques; 541.34515
• DOI: 10.1016/j.jaerosci.2017.07.006
• Languages: English
• ISSNs: 0021-8502

Abstract

Abstract: Particles deposited on an outdoor surface can be resuspended by wind gusts, become airborne, and be inhaled if small enough. If toxic or infectious, these particles may be dangerous for the populace health. It is therefore important to determine under which weather conditions a deposit of particle could be resuspended to implement the best response actions and plan clean-up. To this scope, one needs to consider the competing forces acting on the particle keeping it attached to the surface (gravity and adhesion) or trying to remove it (aerodynamic forces, i.e., lift and drag). This paper reviews the current understanding of the aforementioned forces for colloidal spherical particles and extends the existing theories to rod-shaped particles, representative for instance of Bacillus spores. In particular, for the adhesion force, the Derjaguin approximation was used and the adhesion force was computed from the radii of curvature of the particle and the surface at the point of closest approach. For the aerodynamic forces, we re-derived the equations for the drag and lift forces accounting for the shape of the particle. Both smooth and rough surfaces will be discussed, the former as idealized cases, the latter as more representative of real outdoor surfaces. Highlights: Bacillus spores can be approximated with spheroidal or rod-shaped particles. The stable configuration for spheroidal particles is flat on the surface (side-on). Adhesion and aerodynamic forces were rederived for spheroidal particles. Rabinovich et al. model for adhesion was extended to spheroidal particles. Correlations for both smooth and rough surfaces were presented.