Use of the boundary element method to determine the sampling efficiency of blunt aerosol samplers

Abstract

Blunt samplers are widely used in occupational hygiene and environmental air monitoring in order to determine the concentration of particles in the atmosphere. The rate of aspiration will depend on the features of the fluid flow, which are influenced by the sampler, and also the nature of the particles. Although past research has led to a greater understanding of the performances of blunt samplers, there is still a need for a better understanding of the factors which govern the performances of such devices. In this work the Boundary Element Method is adopted to model the problem. This allows for an accurate description of the fluid behaviour near the sampler to be obtained and hence the behaviour of the particles in the flow determined. This results in an accurate prediction of the aspiration efficiency of the sampler which is necessary when using such devices. The method is particularly useful for this problem as it can easily be adapted to any shape of sampler with sampling taking place at any location on the sampler body. It also makes it possible to include the finite size of the sampling orifice in the model which has not been possible in previous mathematical investigations.