Nonequilibrium fluctuations of an interface under shear

TL;DR

This paper investigates how shear flow affects the fluctuations of an interface, revealing non-equilibrium behavior, reduced interface displacement, and universal fluctuation features consistent with experiments.

Contribution

It demonstrates that shear flow induces non-equilibrium fluctuations with universal characteristics, extending fluctuating hydrodynamics to driven interfaces.

Findings

Thermal fluctuations are driven out of equilibrium by shear.

Mean square displacement of the interface is reduced under flow.

Fluctuation features can be factorized into a single control parameter.

Abstract

The steady state properties of an interface in a stationary Couette flow are addressed within the framework of fluctuating hydrodynamics. Our study reveals that thermal fluctuations are driven out of equilibrium by an effective shear rate that differs from the applied one. In agreement with experiments, we find that the mean square displacement of the interface is strongly reduced by the flow. We also show that nonequilibrium fluctuations present a certain degree of universality in the sense that all features of the fluids can be factorized into a single control parameter. Finally, the results are discussed in the light of recent experimental and numerical studies.