ASPIRATION EFFICIENCY OF A THIN-WALLED SHALLOW-TAPERED SAMPLER REAR-FACING THE WIND

The aspiration efficiency of a thin-walled, shallow-tapered aerosol sa mpler, as studied by Vincent et al. (1986, J. Aerosol Sci. 17, 211-224 ), which is rear-facing the wind is numerically investigated. The turb ulent fluid flow is predicted by employing the control volume, finite- difference method with a body-fitted coordinate system and a low Reyno lds number k-epsilon turbulence model. The particle trajectories are c alculated by integrating the particle equations of motion using either the turbulent instantaneous fluid velocity (a stochastic model) or th e mean fluid motion (the mean motion model). The aspiration efficiency for thin-walled, shallow-tapered samplers which rear-face the wind as predicted by the two models, are in good agreement and although the r esults show an unusual behaviour they agree reasonably well with all t he available experimental data.