ABSTRACT
Attention to the water velocity around air bubbles is given because the water velocity components have to be known when solving the particle motion equation as described in the following chapters. Briefly, the velocity is an important parameter governing the particle trajectory around air bubbles, which controls the bubble-particle encounter mechanics and the bubble-particle sliding interaction, and hence the bubble-particle attachment and detachment. In this chapter, the hydrodynamics of the water velocity around bubbles with either a mobile or an immobile surface will be described. Both the analytical and empirical approximate solutions to the continuity and Navier-Stokes equations for the velocity components will be presented. The effect of the gas hold-up will be included in the approximate expressions. Comparison with the available experimental data will be made.
