In-flight collision behaviour of droplets on a spherical particle falling under gravity

Droplet-particle interaction is critical in design of many industrial processes. In the current work, a systematic experimental study of the impact of water droplets on a moving glass particle falling under gravity at NTP was investigated by a high speed imaging technique. The droplet and particle impact velocities were varied in the experiment independently to observe the effect on the collision outcome. In the entire operating range, the droplets were observed to undergo inelastic collision resulting into complete deposition onto the particle surface forming a thin film. Significant deflection in the particle trajectory during collision was observed at higher droplet Weber number however this deflection was observed to decrease when particle velocity was increased. Two dimensional CFD simulations were also carried out using the Volume of Fluid method in conjunction with the dynamic meshing technique resulting in qualitative agreement with the experimental observations.