Rupture of Thin Film of Surfactant Solution Due to Penetration of Spherical Particle

Abstract

We experimentally investigated the rupture conditions of a thin film of an aqueous surfactant solution when a spherical particle with a finite falling velocity penetrates the film. When the sphere passes through the film, the film wraps around the sphere, and a gas layer is maintained between the film and the spherical surface. When the velocity of the sphere is small, perforation occurs in the wrapping film below the equator of the sphere and the contact line moves along on the sphere surface. The energy instability occurs at a certain position of the contact line on the sphere surface, leading to rupture of the entire thin film. As the sphere velocity is increased, the perforation of the wrapping film occurs above the equator. In this condition, the probability of thin film rupture increases, since the perforation of the wrapping film immediately leads to rupture of the entire film. The motion of the gas between the thin film and the spherical surface was considered analytically from the balance between surface tension and viscous force. According to the result, the velocity condition above which the wrapping thin film could exist beyond the equator of the sphere was evaluated.