A numerical study of the capture of hydrophobic particles by a buoyant bubble

When a buoyant bubble rises through a suspension of hydrophobic particles, particles colliding with the bubble generally will stick to it and are thus carried upward with the bubble. Here, we use fully resolved numerical simulations to examine the rate of capture by a single bubble in a domain containing a particle suspension. The bubble is followed for a long enough time to gather several particles, and we examine the effect of the governing parameters on the rate of accumulation for modest bubble Reynolds numbers. The results show that the strongest dependency is on the volume fraction, where the capture rate of particles decreases rapidly as particles accumulating on the bubble prevent the attachment of other particles. The capture efficiency decreases slightly as the bubbles become more deformable since particles at the bottom of the bubble elongate it, decrease its cross-sectional area, and increases with particle size. The effect of other parameters is small, for the parameter ranges simulated here.