Nonuniform particle distribution and interference between removal mechanisms during unsteady aerosol deposition from a rising spherical bubble

Motegi, Kosuke  ; Shibamoto, Yasuteru ; Kukita, Yutaka

Lagrangian particle tracking simulations are performed on aerosol particle removal from a spherical bubble rising in a water pool. The bubble internal circulation is assumed to be given by the Hill's vortex stream function. Monodispersed particles in the 0.1-1.0 um radius range are simulated. The results are discussed with a focus on the development of particle concentration profile and its influence on removal rates, with the aid of comparisons with Eulerian models including the lumped-parameter model by Fuchs. The results are discussed with a focus on the development of particle concentration profile and its influence on removal rates, with the aid of comparisons with Eulerian models including the lumped-parameter model by Fuchs. It is shown that a quick growth of bubble-surface diffusion layer causes a transition of dominant removal mechanisms from unsteady Brownian diffusion to inertial migration. Fuchs's model, not designed to consider such transition, overpredicts the removal rates for small particles. It is also shown that inertial migration produces a surface-peaked concentration profile in the bubble, resulting in higher removal rates than predicted by Fuchs's lumped-parameter model.