Viscoelastic Multicomponent Fluids in confined Flow-Focusing Devices

TL;DR

This study uses numerical simulations to explore how elasticity affects liquid thread break-up in microfluidic devices, revealing that viscoelasticity stabilizes and shifts the break-up point closer to the junction.

Contribution

It demonstrates the impact of viscoelasticity on droplet formation in microfluidic flow-focusing devices using lattice Boltzmann simulations, a novel application in this context.

Findings

Viscoelasticity stabilizes the break-up process.

The break-up point moves closer to the cross-junction with elasticity.

Polymer feedback stress increases in corner flows.

Abstract

The effects of elasticity on the break-up of liquid threads in microfluidic cross-junctions is investigated using numerical simulations based on the "lattice Boltzmann models" (LBM). Working at small Capillary numbers, we investigate the effects of non-Newtonian phases in the transition from droplet formation at the cross-junction (DCJ) and droplet formation downstream of the cross-junction (DC) (Liu & Zhang, ${\it Phys. Fluids.}$ ${\bf 23}$, 082101 (2011)). Viscoelasticity is found to influence the break-up point of the threads, which moves closer to the cross-junction and stabilizes. This is attributed to an increase of the polymer feedback stress forming in the corner flows, where the side channels of the device meet the main channel.