A theory of coalescence

Abstract Thinning of a liquid film between two “touching” bubbles is the process by which the two bubbles coalesce. A theory is proposed of such a process which predicts the thinning to occur in two stages. The first stage is an extremely rapid thinning of the film down to a quasi-equilibrium thickness, which is calculated by the equation: The second stage is the further thinning of the quasi-equilibrium film down to the rupture and the time required for this stage is the overall coalescence time. Within given assumptions, two possible relations for the time are given: where f is a known function of the group crk 2 /γ. Whenever crk 2 /γ is less than about 2, coalescence is an extremely rapid process and this is the case for pure liquids and sufficiently dilute solutions.