A new model for the acoustic wake effect in aerosol acoustic agglomeration processes

The acoustic wake effect has been considered the main agglomeration mechanism in the aerosol acoustic agglomeration processes. However, the existing theoretical model for the acoustic wake effect, which was proposed half century ago, is not accurate enough and overestimates the perturbation velocity in the vicinity of particles by as high as approximately 50%. In this paper, a new model for the acoustic wake effect is established, in which an approximate expression is constructed to describe the perturbation velocity. The newly developed model has been verified to be more accurate than the existing model by both theoretical analysis of boundary conditions and computational fluid dynamics simulation. The trajectories of two particles in a horizontal sound field are calculated based on the new model and the existing model. The results show that the new model corrects the range of initial orientation angle for two particles to successfully agglomerate, which was overestimated in the existing model. Moreover, the collision efficiency of two different-sized particles under the acoustic wake effect is found to be larger in the simulation by the new model than that by the existing model. The new model can be used as a reasonably accurate tool not only for calculating the agglomeration of two particles, but also for the numerical simulation of acoustic agglomeration of an aerosol containing a large number of particles due to its low computational cost.