Study of Instability of Liquid Jets Under Gravity

TL;DR

This paper investigates the instability and breakup of water jets under gravity, focusing on the role of recoil capillary waves as a source of perturbation waves, and presents experimental verification of their existence.

Contribution

The study provides experimental evidence supporting recoil capillary waves as a key origin of perturbation waves in water jet breakup, expanding understanding beyond classical theories.

Findings

Recoil capillary waves are confirmed to exist and influence jet instability.

Experimental results support the hypothesis that recoil waves contribute to perturbation formation.

The study offers preliminary data on the effect of recoil waves on jet breakup.

Abstract

Breakup of water jets under gravity is a common-place phenomenon. The role of surface tension in the instability of water jets was recognized by Rayleigh and the theory propounded goes by the name of Plateau-Rayleigh theory. The necks and bulges down along the jet-length that are created by perturbation waves of wavelengths larger than a certain value keep growing with time and ultimately cause the jet to breakup into drops. The effect of perturbation waves have been investigated experimentally and found to confirm the essentials of the theory. However, there is no unanimity about the origin of these perturbation waves. Recently, the idea of recoil capillary waves as an important source of the perturbation waves has been emphasized. The recoil of the end point of the remaining continuous jet at its breakup point is considered to travel upward as a recoil capillary wave which gets reflected at the mouth of the nozzle from which the jet originates. The reflected capillary wave travels along the jet downward with its Doppler shifted wavelength as a perturbation wave. We set up an experiment to directly verify the existence and effect of the recoil capillary waves and present some preliminary results of our experiment.