Online

Faletra, Melissa Kathleen

Mechanical Engineering

2014

MS

The problem of the falling under gravity suspension droplet was examined for cases where the droplet contains particles with different densities and different sizes. Cases examined include droplets composed of uniform-size particles with two different densities, of uniform-density particles of two different sizes, and of a distribution of particles of different densities. The study was conducted using both simulations based on Oseenlet particle interactions and laboratory experiments. It is observed that when the particles in the suspension droplet have different sizes and densities, an interesting segregation phenomenon occurs in which lighter/smaller particles are transported downward with the droplet and preferentially leave the droplet by entering into the droplet tail, whereas heavier/larger particles remain for longer periods of time in the droplet. When computations are performed with two particle densities or two particle sizes, a point is eventually reached where all of the lighter/smaller particles have been ejected from the droplet, and the droplet continues to fall with only the heavier/larger particles. A simple model explaining three stages of this segregation process is presented.