Aerosol scavenging by drops : deriving a collection kernel from microphysical modelling

Scavenging aerosol particles by droplets is an efficient way of removing solid particles from gases. Despite its interest for both industrial applications and occupational health, predicting realistic removal rates by means of a simple collection kernel is still a challenge (Belut (2014)). A realistic collection kernel must simultaneously take into account the aerosol dynamics and the liquid-gas interactions around a moving drop. Besides flow pattern, the capture of particles is also affected by heat transfer, phase change, electric forces, Brownian motion, and inertial effects that must be taken into account. Examining the collection kernel of Wang et al. (1978) (low inertia particles undergoing Brownian, phoretic and electrostatic scavenging) or the collection kernel of Mohebbi et al. (2003) (inertial capture only) shows the lack of universality of scavenging kernels but also the lack of numerical or experimental reference data allowing a more general scavenging kernel to be derived. We propose to extend available reference data using numerical experiments. A global scavenging kernel is then derived from the collection efficiencies obtained in numerical simulations.