VII-1

J. Eggers

Universit at GH Essen

Abstract

We consider the motion of a fluid jet driven by surface tension. To reduce surface area, the radius of the fluid neck locally goes to zero in finite time and a drop separates. Since the curvature goes to infinity, this is a singularity of the equations of motion, which occurs on scales separated from those set by the initial conditions. As a consequence, the motion close to the singularity is self-similar, and its structure is determined by the balance of surface tension with viscous forces and inertia. In the absence of an outer fluid, the asymptotic solution is completely universal, but may pass through a variety of transient regimes, depending on initial condition. In the case of two-phase flow, inertia asymptotically drops out of the problem. The long-ranged character of the Stokes interaction leads to logarithmic corrections to power-law scaling. We discuss the comparison between theory and experiment and outline unsolved problems.