Periodic Droplet Formation in Chemically Patterned Microchannels

TL;DR

This study uses simulations to reveal how chemically patterned microchannels induce unique, periodic droplet formation and complex morphological instabilities in phase-separated binary fluids, driven by flow and substrate interactions.

Contribution

It demonstrates the emergence of periodic droplet formation and morphological instabilities in binary fluids flowing through chemically patterned microchannels, highlighting non-linear dynamics without hydrodynamic interactions.

Findings

Periodic monodisperse droplet formation observed

Bifurcation between steady and oscillatory behaviors

Complex dynamics arise from flow-pattern interactions

Abstract

Simulations show that when a phase-separated binary AB fluid is driven to flow past chemically patterned substrates in a microchannel, the fluid exhibits unique morphological instabilities. For the pattern studied, these instabilities give rise to the simultaneous, periodic formation of monodisperse droplets of A-in-B and B-in-A. The system bifurcates between time-independent behavior and different types of regular, non-decaying oscillations in the structural characteristics. The surprisingly complex behavior is observed even in the absence of hydrodynamic interactions and arises from the interplay between the fluid flow and patterned substrate, which introduces non-linearity into the dynamical system.