Vorticity structuring and Taylor-like velocity rolls triggered by gradient shear bands

TL;DR

This paper introduces a new mechanism for vorticity structuring and Taylor-like velocity rolls in complex fluids, based on the linear instability of gradient shear banded flow, supported by numerical simulations of the Johnson-Segalman model.

Contribution

It proposes a novel instability mechanism for vorticity structuring in shear banded flows, challenging existing shear banding theories.

Findings

Vorticity structuring can be triggered by linear instability.

Finite interface thickness persists even as stress diffusivity approaches zero.

Numerical evidence supports the proposed mechanism.

Abstract

We suggest a novel mechanism by which vorticity structuring and Taylor-like velocity rolls can form in complex fluids, triggered by the linear instability of one dimensional gradient shear banded flow. We support this with a numerical study of the diffusive Johnson-Segalman model. In the steady vorticity structured state, the thickness of the interface between the bands remains finite in the limit of zero stress diffusivity, presenting a possible challenge to the accepted theory of shear banding.