Re-laminarization of elastic turbulence

TL;DR

This paper demonstrates that elastic turbulence in viscoelastic flows can be suppressed and flow re-laminarized through elastic wave interactions, leading to drag reduction at low Reynolds numbers.

Contribution

It reveals a physical mechanism where elastic waves interact with vorticity to cause flow re-laminarization and drag reduction in elastic turbulence.

Findings

Elastic waves correlate with drag increase above ET onset.

Higher Weissenberg number increases elastic wave frequency.

At high frequency, elastic waves decay, reducing turbulence.

Abstract

We report frictional drag reduction and a complete flow re-laminarization of elastic turbulence (ET) at vanishing inertia in a viscoelastic channel flow past an obstacle. We show that intensity of observed elastic waves and wall-normal vorticity correlate well with the measured drag above the ET onset. Moreover, we find that the elastic wave frequency grows with Weissenberg number, and at sufficiently high frequency it causes decay of the elastic waves, resulting in ET attenuation and drag reduction. Thus, this allows us to substantiate a physical mechanism, involving interaction of elastic waves with wall-normal vorticity fluctuations, leading to the drag reduction and re-laminarization phenomena at low Reynolds number.