Experimental investigation of water jets under gravity

TL;DR

This paper experimentally investigates water jets under gravity, confirming the presence of recoil capillary waves and identifying a boundary where gravity overtakes surface tension in jet behavior.

Contribution

It verifies the existence of recoil capillary waves and explores the transition point where gravity effects dominate over surface tension in water jets.

Findings

Recoil capillary waves are experimentally confirmed.

Wavy jet surface appears immediately after emergence.

A boundary exists where gravity effects surpass surface tension.

Abstract

The Plateau-Rayleigh theory essentially explains the breakup of liquid jets as due to growing perturbations along the length of the jet. The essential idea is supported by several experiments carried out in the past. Recently, the existence of a feedback mechanism in the form of recoil capillary waves was proposed to enhance the effect of the perturbations. We experimentally verify the existence of such recoil capillary waves. Using our experimental setup we further show that the wavy nature of the jet surface appears almost right after the emergence of the jet from the nozzle irrespective of the recoil capillary wave feedback. Moreover, our experimental results indicate existence of a sharp boundary, along the length of the continuous jet, beyond which gravitational effect dominates over the surface tension.