Morphology of a stream flowing down an inclined plane. Part 1. Braiding

Abstract

A jet of fluid flowing down a partially wetting inclined plane usually meanders. In this paper, we demonstrate that meandering on a smooth plane can be suppressed by maintaining a constant volume flow rate. In the absence of meandering, we experimentally observe the jet developing a braided structure with non-monotonic width. This flow pattern is theoretically explained as the result of the interplay between surface tension that tends to narrow the jet down and fluid inertia that drives the jet width to expand. The theory also predicts a bifurcation between the braiding regime and a non-meandering non-braiding flow, which is confirmed by experiment.