Stretching and buckling of small elastic fibers in turbulence

TL;DR

This paper investigates how small elastic fibers in turbulence mostly remain straight but occasionally buckle due to local shear, revealing intermittent buckling events driven by turbulent correlations.

Contribution

It introduces a numerical study of fiber buckling in turbulence, highlighting the role of long-range correlations and the analogy to activation processes.

Findings

Buckling occurs intermittently in turbulent flows.

Long-range Lagrangian correlations influence buckling events.

Buckling is akin to an activation process with turbulence playing the role of temperature.

Abstract

Small flexible fibers in a turbulent flow are found to be most of the time as straight as stiff rods. This is due to the cooperative action of flexural rigidity and fluid stretching. However, fibers might bend and buckle when they tumble and experience a strong-enough local compressive shear. Such events are similar to an activation process, where the role of temperature is played by the inverse of Young's modulus. Numerical simulations show that buckling occurs very intermittently in time. This results from unexpected long-range Lagrangian correlations of the turbulent shear.