Splitting of localized disturbances in viscoelastic channel flow

TL;DR

This paper investigates how localized disturbances in inertia-less viscoelastic channel flow can split into separate pulses due to non-linear interactions, revealing a new approach to studying elastic instability at high elasticity.

Contribution

It introduces a simplified model showing pulse splitting from localized disturbances and demonstrates experimental transition to this regime, advancing understanding of elastic instability.

Findings

Localized disturbances can split into two pulses at high elastic stresses.

A transition to pulse-splitting regime is experimentally demonstrated.

Non-linear interactions are key to pulse splitting in viscoelastic flow.

Abstract

We examine the response of an inertia-less viscoelastic channel flow to localized perturbations. A simplified model shows that the non-linear interaction between the velocity and elastic stress fields can split an initial pulsed disturbance into two separate pulses if the initial disturbance and the base elastic stress are sufficiently high. In accordance, we demonstrate that a transition to a pulse-splitting regime can be achieved experimentally. These results suggest a possible new direction for studying the elastic instability of viscoelastic channel flows at high elasticity through the growth of localized perturbations.