Agglomeration of Chain-Like Combustion Aerosols Due to Brownian Motion

Abstract

A dynamic Monte Carlo-type lattice model has been developed to simulate the agglomeration of nonspherical chain-like agglomerate combustion aerosols due to Brownian motion. Simulations are carried out in the free molecular and continuum regimes, for both initial mono-disperse and initial lognormally distributed aerosols, with and without source mechanisms, at number densities ranging from 1 × 10⁹ cm⁻³ to 5 × 10,0 cm⁻³. Preservation of the chain-like structure of the agglomerate is accomplished throughout the simulation by describing the agglomerate as fractal, that is, scale-invariant, self-similar with a noninteger dimensionality. The clusters' diffusion coefficient is employed as the criterion that governs the probability for cluster movement. Simulation results indicate that cluster growth is more rapid in the free molecular regime than in the continuum, and the rate of agglomeration increases when the structure of the agglomerate is more fragmented (lower fractal dimension). Favorable agreement is obtained between the cluster agglomeration simulations and the analytical solutions to the coagulation equation for the discrete size spectrum.