Aerodynamic bag breakup of a polymeric droplet

TL;DR

This study experimentally investigates how liquid elasticity influences the aerodynamic bag breakup of polymeric droplets, revealing that elasticity can inhibit fragmentation and providing a framework to predict breakup behavior.

Contribution

It introduces a new experimental analysis of polymeric droplet breakup, highlighting the role of elasticity and establishing criteria for fragmentation occurrence.

Findings

Polymeric droplets resist fragmentation due to elasticity.

Initial deformation dynamics are similar for Newtonian and polymeric droplets.

Fragmentation can be completely inhibited depending on elasticity.

Abstract

The aerodynamic breakup of a polymeric droplet in the bag breakup regime is investigated experimentally and compared with the result of the Newtonian droplet. To understand the effect of liquid elasticity, the Weber number is kept fixed ($\approx$ 12.5) while the elasticity number is varied in the range of $\sim 10^{-4}-10^{-2}$. Experiments are performed by allowing a liquid droplet to fall in a horizontal, continuously flowing air stream. It is observed that the initial deformation dynamics of a polymeric droplet is similar to the Newtonian droplet. However, in the later stages, the actual fragmentation of liquid mass is resisted by the presence of polymers. Depending upon the liquid elasticity, fragmentation can be completely inhibited in the timescale of experimental observation. We provide a framework to study this problem, identify the stages where the role of liquid elasticity can be neglected and where it must be considered, and finally, establish a criterion that governs the occurrence or the absence of fragmentation in a specified time period.