Theoretical Determination of the Efficiency of Aerosol Particle Collection by Falling Columnar Ice Crystals

Abstract

A theoretical model for the removal of aerosol particles by falling columnar ice crystals which incorporates gravitational, inertial, thermophoreic, diffusiophoretic, and electrostatic mechanisms has been formulated. The results of this trajectory model, combined with earlier resuslts, determine the collection efficiency for submicron particles as a flux onto a collector surface for any geometry and due to Brownian diffusion, thermo- and diffusio-phoresis as well as electrostatic forcing. The combination of these two models provides scavenging efficiencies for aerosol particles of radii 0.001 ≤ r ≤ 10.0?m by columnar ice crystals with associated Reynolds numbers ranging from 0.5 to 20.0. This quantiative study indicates the effect of particle size, charge, and atmospheric conditions.