Interface instability in shear banding flow

TL;DR

This paper investigates the complex spatio-temporal behavior of the interface in shear-banding flow of wormlike micelles, revealing an instability along the vorticity direction and proposing a symmetry-based model to explain observed patterns.

Contribution

It introduces the first detailed analysis of interface instability in shear banding flow and presents a qualitative model based on flow symmetry.

Findings

Identified interface instability along the vorticity direction.

Mapped different spatio-temporal regimes during stress plateau.

Proposed a symmetry-based model explaining pattern formation.

Abstract

We report on the spatio-temporal dynamics of the interface in shear-banding flow of a wormlike micellar system (cetyltrimethylammonium bromide and sodium nitrate in water) during a start-up experiment. Using the scattering properties of the induced structures, we demonstrate the existence of an instability of the interface between bands along the vorticity direction. Different regimes of spatio-temporal dynamics of the interface are indentified along the stress plateau. We build a model based on the flow symetry which qualitatively describes the observed patterns.