On the mechanism of elasto-inertial turbulence

TL;DR

This paper investigates the mechanisms behind elasto-inertial turbulence in polymer-laden flows through direct numerical simulations, revealing how polymer dynamics influence flow structures and turbulence onset.

Contribution

It provides a detailed analysis of the coupling between polymer behavior and flow structures, clarifying the mechanism of elastic instabilities and turbulence initiation.

Findings

Polymer additives induce elastic instabilities affecting turbulence.

The study explains early turbulence onset in polymeric flows.

An analogy with 2D turbulence energy cascades is identified.

Abstract

Elasto-inertial turbulence is a new state of turbulence found in flows with polymer additives . The dynamics of turbulence generated and controlled by such additives is investigated from the perspective of the coupling between polymer dynamics and flow structures. Direct numerical simulations of channel flow with Reynolds numbers ranging from 1000 to 6000 (based on the bulk and the channel height) are used to study the formation and dynamics of elastic instabilities and their effects on the flow. The resulting mechanism of interactions between polymer dynamics and the flow helps resolve a long-standing controversy in the understanding of polymer drag reduction and explains the phenomenon of early turbulence, or onset of turbulence at lower Reynolds numbers than for Newtonian flows, previously observed in polymeric flows. Polymers also point out an interesting analogy with the forward and backward energy cascade in two-dimensional turbulence.