The evolution of bimodal size distribution with spatially inhomogeneous particle concentration

Abstract

In the present study, a simple model of Brownian agglomeration and diffusion for aerosol particles is developed to study the formation and evolution of bimodal size distribution with spatially inhomogeneous particle concentration. The calculation is based on the asymptotic solution for Brownian agglomeration, and the particle concentration distribution in 1-D space is simplified with a Gauss complementary error function, and the local self-preserving particle size distribution assumes the log-normal. The asymptotic analysis reveals that the global particle size distribution is unimodal initially; as time advances, the bimodality is formed; but at long time, the global particle size distribution returns to a unimodal function. The result shows that the inhomogeneity of particle concentration is an important factor in the formation of bimodal size distribution.