Breakup of thin liquid sheets through hole–hole and hole–rim merging

G.G Agbaglah

doi:10.1017/jfm.2020.1016

Abstract

Highlights

The breakup of a liquid stream into droplets is commonly encountered in nature and widely used in industrial applications, such as pesticide spraying, spray painting, fuel-injection systems, cooling, dispersal of biological agents and many more
We study the merging process of two distinct holes and a single hole with a straight end rim, using three-dimensional numerical simulations
Three-dimensional numerical simulations of the merging process of two distinct holes, referred to as the hole–hole case, and a hole with a straight rim, referred to as the hole–rim case, are presented using different liquid sheet thicknesses ranging from e0 = 25 μm to e = 6e0 = 150 μm, which correspond to liquid sheet thicknesses obtained in liquid–gas atomization (Ling et al 2017)

Summary

Introduction

The breakup of a liquid stream into droplets is commonly encountered in nature and widely used in industrial applications, such as pesticide spraying, spray painting, fuel-injection systems, cooling, dispersal of biological agents and many more. The process of fragmentation of fluid masses, referred to as the atomization phenomenon, is mainly thought of as a consequence of the momentum difference between the liquid and the surrounding gas This momentum difference induces a shear instability on the liquid–gas interface which forms wave structures. The liquid sheet oscillates and breaks up into droplets Another important breakup mechanism is the formation of holes which appear in waves prior to the formations of ligaments. The holes expand, merge with each other or with a retracting end rim and break the liquid sheet into droplets; see for instance figures 9 and 10 of Ling et al (2017). One most common outcome of hole collision, which can be observed in different configurations, is the formation of a smooth or rough liquid bridge which subsequently detaches in a ligament that breaks into multiple drops or collapses into a single large drop. We aim at a comprehensive understanding of the process of drop formation from hole–hole and hole–rim merging

Numerical method and preliminary simulations

Hole–hole and hole–rim merging processes in a thin liquid sheet

Discussion and conclusion