Particle Deposition with Thermophoresis in Laminar and Turbulent Duct Flows

Abstract

A numerical simulation procedure for studying deposition of aerosol particles in duct flows including the effect of thermal force under laminar and turbulent flow conditions is developed. An improved model for thermophoretic force acting on small particles is presented. Perturbation based analytical expressions for velocity and temperature profiles are used in the analysis for the laminar duct flow. The Reynolds stress transport model (RSM) of the FLUENT code is used to evaluate the mean flow and temperature fields for the turbulent duct flow case. The instantaneous fluctuation velocity field is generated by the continuous filtered white noise model. Effects of Brownian diffusion, thermophoresis, lift force, and gravity are included in the computation. Ensembles of particle trajectories are generated and statistically analyzed. Particle dispersion from a point source in the presence of a temperature gradient field in laminar and turbulent duct flows is studied. For an initially uniform concentration, several simulations for transport of aerosol particles of various sizes in different temperature gradient fields are performed, and the corresponding collection efficiencies and deposition velocities are evaluated. The results are compared with the existing experimental data and discussed.