Magnetorotational-type instability in Couette-Taylor flow of a viscoelastic polymer liquid

TL;DR

This paper identifies a viscoelastic flow instability in Couette-Taylor systems that closely resembles the astrophysical magnetorotational instability, offering a more accessible experimental analogue for studying such phenomena.

Contribution

It introduces a novel instability in viscoelastic fluids analogous to MRI, distinguishing it from known centrifugal and elastic instabilities.

Findings

Identifies conditions for the onset of the viscoelastic MRI-like instability.

Characterizes the properties of the preferred unstable modes.

Suggests easier experimental investigation compared to astrophysical MRI.

Abstract

We describe an instability of viscoelastic Couette-Taylor flow that is directly analogous to the magnetorotational instability (MRI) in astrophysical magnetohydrodynamics, with polymer molecules playing the role of magnetic field lines. By determining the conditions required for the onset of instability and the properties of the preferred modes, we distinguish it from the centrifugal and elastic instabilities studied previously. Experimental demonstration and investigation should be much easier for the viscoelastic instability than for the MRI in a liquid metal. The analogy holds with the case of a predominantly toroidal magnetic field such as is expected in an accretion disk and it may be possible to access a turbulent regime in which many modes are unstable.