AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
The Collision Rates of Charged Aerosol Particles in Shear Fields
HUAN YANG, Christopher Hogan Jr., University of Minnesota
Abstract Number: 28 Working Group: Aerosol Physics
Abstract Collisions between charged particles have a large influence on the behavior of many aerosol systems (e.g. in fluidized beds, electrostatic precipitators, volcanic plumes, and dust storms). Accurate collision rate calculations for charged species can therefore be of critical importance in predicting aerosol behavior. In determining particle-particle and particle-ion collision rates, the influence of thermal (Brownian) energy is often considered simultaneously with the influence of electrostatic energy, and a number of prior works have been devoted to collision rate calculation considering combined Brownian and electrostatically driven motion. However, for submicrometer and supermicrometer particles, Brownian motion is often negligible in comparison to the influence of differential motion brought about by laminar (linear) shear gradients present in flowing aerosols. Despite their potential significance for sub- and supermicrometer particles, it appears that the combined influences of shear and electrostatic potentials on particle-particle/particle-ion collisions in aerosols have not been investigated previously.
In this study, we have developed a trajectory calculation based approach to determine the collision rate coefficient between particles, accounting for the simultaneous effects of laminar shear gradients and electrostatic potentials (both attractive and repulsive). We additionally consider finite particle inertia (e.g. Stokes number effects). In this presentation, we outline the numerical approach developed, and present non-dimensionalized equations (dependent upon the Stokes number, electrostatic to kinetic energy ratio, and the particle size ratio) which enable simple calculation of collision rate coefficients in a wide range of circumstances.