Scalability of inertial particle deposition in bubbles with internal circulation

内部循環を持つ気泡内でも慣性粒子沈着のスケーラビリティ

茂木 孝介  ; 柴本 泰照 ; 久木田 豊

Motegi, Kosuke; Shibamoto, Yasuteru; Kukita, Yutaka

Inertial deposition of small (less than a few m in diameter) aerosol particles in mm-scale bubbles is an old but unsettled issue in modeling of pool scrubbing phenomenon. Whereas existing practical models give no specific consideration to the bubble-internal transport, some studies have shown that inertial transport affects considerably the particle deposition rate. We show, on the basis of Lagrangian simulations of particles advected by steady internal circulation in a spherical bubble, that particle centrifugal velocity becomes scale invariant for low- Stokes numbers (St ) when the characteristic timescale is chosen to be that for transversal particle motion at the Stokes terminal velocity corresponding to the local fluid acceleration. Because a scaling law can be derived by running simulations with a small number of particles, it can provide a practical tool for considering the influence of inertial particle transport within the bubble on the decontamination factor.