Elasto-inertial turbulence

TL;DR

This paper introduces elasto-inertial turbulence (EIT), a new disordered flow state in complex fluids with elastic properties, which occurs at lower Reynolds numbers and reduces drag, challenging previous turbulence models.

Contribution

It demonstrates the existence of EIT in complex fluids, showing it replaces traditional turbulence at lower Reynolds numbers and explains the maximum drag reduction asymptote.

Findings

EIT occurs at lower Reynolds numbers than Newtonian turbulence.

EIT significantly reduces drag compared to classical turbulence.

Theoretical analysis links EIT to high extensional viscosity in complex fluids.

Abstract

Turbulence is ubiquitous in nature yet even for the case of ordinary Newtonian fluids like water our understanding of this phenomenon is limited. Many liquids of practical importance however are more complicated (e.g. blood, polymer melts or paints), they exhibit elastic as well as viscous characteristics and the relation between stress and strain is nonlinear. We here demonstrate for a model system of such complex fluids that at high shear rates turbulence is not simply modified as previously believed but it is suppressed and replaced by a new type of disordered motion, elasto-inertial turbulence (EIT). EIT is found to occur at much lower Reynolds numbers than Newtonian turbulence and the dynamical properties differ significantly. In particular the drag is strongly reduced and the observed friction scaling resolves a longstanding puzzle in non-Newtonian fluid mechanics regarding the nature of the so-called maximum drag reduction asymptote. Theoretical considerations imply that EIT will arise in complex fluids if the extensional viscosity is sufficiently large.