Low Reynolds number turbulent flows over elastic walls

TL;DR

This paper demonstrates that elastic walls can sustain turbulent-like flows at any Reynolds number by tuning wall elasticity, revealing mechanisms for turbulence production and potential microfluidic mixing applications.

Contribution

It introduces a novel approach to sustain turbulence at low Reynolds numbers using elastic walls and explains the underlying physical mechanisms involved.

Findings

Elastic walls can sustain turbulence at any Reynolds number.

Two mechanisms for turbulence production are identified.

Elastic wall energy input enhances mixing in microfluidics.

Abstract

We study the laminar and turbulent channel flow over a viscous hyper-elastic wall and show that it is possible to sustain an unsteady chaotic turbulent-like flow at any Reynolds number by properly choosing the wall elastic modulus. We propose a physical explanation for this effect by evaluating the shear stress and the turbulent kinetic energy budget in the fluid and elastic layer. We vary the bulk Reynolds number from 2800 to 10 and identify two distinct mechanisms for turbulence production. At moderate and high Reynolds numbers, turbulent fluctuations activate the wall oscillations, which, in turn, amplify the turbulent Reynolds stresses in the fluid. At very low Reynolds number, the only production term is due to the energy input from the elastic wall, which increases with the wall elasticity. This mechanism may be exploited to passively enhance mixing in microfluidic devices.