DEM analysis of acoustic wake agglomeration for mono-sized microparticles in the presence of gravitational effects

The application of the discrete element method (DEM) to numerical simulation of the acoustic agglomeration of micron-sized mono-dispersed aerosol particles is demonstrated. The conventional DEM technique used in granular dynamics is modified for the simulation of the acoustically induced attractive motion of particles in incompressible fluid. The relationship between the acoustic wake and the gravity is investigated by simulating the binary interaction of two particles for a wide range of particles’ orientations to the sound direction. The main finding obtained by simulation results shows that agglomeration time is solely predefined by the acoustic wake effect independently of gravity. On the other hand, the gravitational motion is contributed by the sound, and an increase of settling velocity due to the sound of individual particles was found. Additionally, two particles surrounded by a system of other particles are illustrated by numerical results. It was also shown that isolated particles demonstrate an overestimated increase of the agglomeration time, which was essentially reduced by the contribution of other particles in the multi-particle system.