Particle-bubble encounter probability with mobile bubble surfaces

The mechanics of encounter between a particle and a bubble with a mobile su rface and of intermediate Reynolds number has been analysed. Water velociti es around the forward bubble surface are approximately predicted using the numerical solution to the Navier-Stokes equation. The order-of-magnitude an alysis is employed to investigate the influence of inertia on the particle velocities around the bubble surface and the particle-bubble encounter (col lision) probability. The predicted probability agrees well with the availab le experimental data. The particle-bubble encounter probability is strongly reduced when the inertial effect is considered. The physical reason behind this is the non-zero tangential water velocity on a mobile bubble surface, which pulls particles away from the forward bubble surface. The predicted collision angle is significantly influenced by the inertial effect. The enc ounter probability prediction in this article is complementary to the avail able encounter probability models with immobile bubble surfaces in flotatio n. (C) 1998 Elsevier Science B.V. All rights reserved.