COALESCENCE BETWEEN SMALL BUBBLES: EFFECTS OF SURFACE TENSION GRADIENT

1 INTRODUCTIONThe rate of coalescence between bubbles is important to the stability of foams,the mo-bility control in tertiary oil recovery,and a broad class of operations in which gas orvapor is the dispersed phase.Therefore,it is very important that the mechanism of thecoalescence process be understood,so that the effects of the physical properties oncoalescence can be assessed.

COALESCENCE BETWEEN SMALL BUBBLES: EFFECTS OF SURFACE TENSION GRADIENT

When two small bubbles approach each other, a dimpled thin liquid film is formed between them. A model is developed for the dynamics of the thinning film with mobile interfaces, in which the effects of interfacial mobility and physical properties on the drainage and rupture of a dimpled liquid film are investigated. The model predicts the coalescence time, which is the time required for the thinning and the rupture of the liquid film, given only the radii of the bubbles and the required physical properties of the liquid and the surface, such as surface tension, London-van der waals constant, and surface diffusion coefficient. The predicted result is in agreement with the experimental results in the literature.