Simulation of acoustic particle agglomeration in poly-dispersed aerosols

Abstract

This report presents application of the MD for the simulation of acoustic agglomeration of poly-disperse aerosol particles. The conventional time-driven MD approach was applied and in-house developed MD code was modified for simulation purposes. The aerosol is assumed to be a system of dispersed spherical fluid particles while the agglomeration may occur between initial smaller particles sequentially forming larger particles. The modelled processes include the agglomeration due to the orthokinetic and acoustic wake mechanisms. Orthokinetic agglomeration refers to the agglomeration due to direct collisions between particles that are entrained at different velocities in the oscillatory motion of the sound field. Acoustic wake mechanisms are those that produce particle interactions through the surrounding medium because of hydrodynamic forces and the asymmetry of the flow field around the particle. It is assumed that the particles collide and agglomerate due to the interactions induced by sound waves. The aggregates formed during the agglomeration process were characterised as aggregates with a different radius to estimate the average radius of the primary particles in individual aggregates. The MD model was validated by comparison against the available analytical solutions. Finally, interaction process of two and four particles investigated and presented.