Computer modelling of the flow of air and aerosols through and onto porous filters, and some applications and modifications of the Parker model

A brief overview of a theoretical model for the movement of aerosol particles through a pore in a filter is given. The aim of the report is to describe the calculation methods involved in the theoretical determination of the impaction efficiency of a Nuclepore filter, consisting of cylindrical holes. The Navier-Stokes equations, derived from a continuum mechanics in terms of a stream function Y and a vorticity vector w, have been used to describe the flow through a cylindrical pore. These equations were solved numerically and the results used to obtain the air velocity at a discrete grid of spatial points. By assuming that Stokes drag force acts on a particle moving with the air towards the pore, a particle trajectory has been calculated. Thus it could be determined wether a particle has deposited on the filter or has passed through the pore in the filter. The interception and impaction efficiencies for subsequent particles after a single particle deposition, have also been investigated