Bridging Elastic and Active Turbulence

TL;DR

This paper uncovers a fundamental connection between elastic and active turbulence, showing their continuum descriptions are analogous and revealing shared topological defect structures and transition behaviors.

Contribution

It demonstrates the macroscopic analogy between elastic and active turbulence and links their topological defect dynamics and flow transitions.

Findings

Polymeric fluids can be viewed as deformable active matter analogues.

Transition to flow suppression involves topological defects similar to active turbulence.

Flow structures and instabilities are driven by activity-like gradients in polymers.

Abstract

Remarkably, even under negligible inertia, the addition of microstructural agents can generate chaotic flow fields. Such behavior can arise in polymer solutions, leading to elastic turbulence, or from active, self-driven particles, which generate active turbulence. Here, we demonstrate a close and hitherto unrecognized connection between these two classes of turbulence. Specifically, we reveal that their continuum descriptions are analogous at the macroscopic level, such that polymeric fluids can be interpreted as a deformable analogue of contractile active matter. Moreover, our numerical results for Kolmogorov flow demonstrate that the transition into the well-known traveling arrowhead structures in elastic turbulence is marked by the emergence of $\pm 1/2$ topological defects, long recognized as a defining feature of active turbulence, in the polymer director field. Importantly, these coherent structures originate from a transverse instability driven by activity-like gradients generated by anisotropically stretched, contractile polymers. At sufficiently strong activity, the system undergoes a transition into a flow-suppressed state characterized by weak polymer stretching and ordering, a behavior that can be explained by analogy with the spontaneous-flow transition observed in channel-confined active nematics.