Collision and Attachment Interactions of Single Air Bubbles with Flat Surfaces in Aqueous Solutions - Drops and Bubbles in Contact with Solid Surfaces - page 236

Figure 14. Influence of the viscosity on the time evaluation of the drop radius [62].
in water. There is a domain of the bubble rise velocity and drag coefficient ver-
sus the bubble equivalent diameter. The interaction of the rising bubbles with the
solid surface is influenced by the bubble kinetic energy and surface energy, the in-
tervening liquid film and the surface roughness and wettability. Interestingly, the
recent studies show that the deformed bubble profile and velocity during the ap-
proach can be normalised to obtain the master curves. The wetting films formed
between the rising bubble and the solid surface can be analysed within the frame-
work of lubrication approximation when the inertial effects can be neglected. When
the bubble surface is clean (free from surfactants), the water velocity at the air-
water film surface is of the order of the bubble rise velocity and the inertial effects
on the film drainage are significant. Both the DLVO and non-DLVO colloidal forces
are relevant to the drainage and rupture of the intervening liquid films. The strong
hydrophobic attraction is influenced by the nanobubbles of dissolved gases in the
solution and at the water-solid surface. The hydrodynamic and molecular-kinetic
models for the spreading and relaxation of the three-phase contact lines have been
reviewed. A combination of the two models can provide a better agreement with
the experimental results.
H. Acknowledgements
This research is supported under Australian Research Council's Discovery Projects
funding scheme (Grants DP0663688 and DP0985079).
I. References
1. Attard, P. and Miklavcic, S. J., Effective spring constant of bubbles and droplets. Langmuir, 17(26)
(2001) 8217-8223.