Perspectives on viscoelastic flow instabilities and elastic turbulence

TL;DR

This paper reviews viscoelastic flow instabilities and elastic turbulence, highlighting their unique behaviors, experimental and simulation tools, and future research directions in complex fluid dynamics.

Contribution

It provides a comprehensive perspective integrating historical context, experimental methods, and modern challenges in understanding viscoelastic flow instabilities and turbulence.

Findings

Viscoelastic fluids exhibit flow instabilities not seen in Newtonian fluids.

Elastic turbulence can occur at low Reynolds numbers.

Experimental and simulation tools are advancing understanding of these phenomena.

Abstract

Viscoelastic fluids are a common subclass of rheologically complex materials that are encountered in diverse fields from biology to polymer processing. Often the flows of viscoelastic fluids are unstable in situations where ordinary Newtonian fluids are stable, owing to the nonlinear coupling of the elastic and viscous stresses. Perhaps more surprisingly, the instabilities produce flows with the hallmarks of turbulence -- even though the effective Reynolds numbers may be $O(1)$ or smaller. We provide perspectives on viscoelastic flow instabilities by integrating the input from speakers at a recent international workshop: historical remarks, characterization of fluids and flows, discussion of experimental and simulation tools, and modern questions and puzzles that motivate further studies of this fascinating subject. The materials here will be useful for researchers and educators alike, especially as the subject continues to evolve in both fundamental understanding and applications in engineering and the sciences.