Non-equilibrium hydrodynamics of a rotating filament

TL;DR

This paper investigates the complex nonlinear behavior of a rotating elastic filament in a fluid, revealing a sharp transition between twirling and overwhirling states and how thermal fluctuations influence this transition.

Contribution

It introduces hydrodynamic simulations that incorporate elasticity and thermal effects to analyze the nonlinear dynamics of rotating filaments, extending previous analytical work.

Findings

The twirling-overwhirling transition is strongly discontinuous.

Thermal fluctuations lower the critical rotational frequency for finite persistence length.

For infinite persistence length, the threshold matches analytical predictions.

Abstract

The nonlinear dynamics of an elastic filament that is forced to rotate at its base is studied by hydrodynamic simulation techniques; coupling between stretch, bend, twist elasticity and thermal fluctuations is included. The twirling-overwhirling transition is located and found to be strongly discontinuous. For finite bend and twist persistence length, thermal fluctuations lower the threshold rotational frequency, for infinite persistence length the threshold agrees with previous analytical predictions.