Numerical Modeling of Aerosol Transport and Removal in Channels Using the Particle Tracking Method

Abstract

Abstract Turbulent transport and deposition of microscopic particles in commonly-used large, and micro-channels were investigated. The objective was to examine the suitability of the Reynolds-averaged Navier-Stokes (RANS)-type turbulence models, along with a Monte-Carlo Lagrangian particle tracking method that accounts for the stochastic particle-turbulent eddy interactions, for the modeling of aerosol transport when a multitude of forces act on the particles. The computer program KIVA-3 (Amsden et al., 1993) was modified and enhanced by adding several turbulence models, and including appropriate models for the effect of the following mechanisms on particle motion: drag, gravity, thermophoresis, Brownian dispersion, and shear-induced (Saffman) lift force. The effect of Brownian motion was modeled by including a random, white noise force term in the particle equation of motion. Parametric simulations were performed, leading to the following main observations. For the transport and deposition of microscopic particles, in addition to the turbulent dispersion, several other dispersion mechanisms were important. The k-ε and Reynolds-stress transport models provided similar predictions for sub-micron particles, but differed significantly for larger particles. The model provided physically consistent results with correct trends in all the simulations. The methodology, however, appears to be expensive in terms of computations, and further work is needed for streamlining the numerical solution methods and physical models.