Study on inertial capture of particles by a droplet in a wide Reynolds number range

Inertial capture of particles by a droplet is the physical basis of wet deposition in the atmospheric environment and wet scrubbing in industries. In this study three-dimensional direct numerical simulations were performed to quantify the characteristics of the flow field and the deposition behavior of the particles with different inertia at seven typical droplet Reynolds numbers (Re). In the vortex shedding regime (270 < Re < 1000), the flow field oscillation induced by vortex shedding resulted in oscillation of particle deposition behavior. The oscillation amplitudes of the particle deposition and normal impact velocity distribution on the droplet surface, and the inertial capture efficiency increased with the droplet Reynolds number increasing while decreased with the particle Stokes number (St) increasing. The time-averaged characteristics of particle deposition were determined by the time-averaged flow field. Re and St are the key parameters which determine the time-averaged inertial capture efficiency of particles by a droplet. In consideration of flow boundary layer evolution with Re, St was modified and a new formula for the inertial capture efficiency was derived. This formula extended the efficiency calculation scope from Re < 210 (by the existing formulas) to Re < 1000, with the maximum relative deviation less than 5%. (C) 2015 Elsevier Ltd. All rights reserved.