Fingering instability of a gravitationally driven contact line

Abstract

Presented here are the results of an experimental study of the flow of a viscous fluid sheet down a dry inclined plane. The three-phase contact line at the front of the flow is initially straight but becomes unstable to a roughly periodic variation in its downslope position when the sheet becomes thin enough. From measurements of the contact line position as a function of time for angles α in the range 0° < α < 55°, the flow is analyzed both before and after the instability occurs, and the development of the finger pattern is parameterized. These results are compared with those found in previous experiments and those predicted by theory.