Effective interactions between inclusions in complex fluids driven out of equilibrium

TL;DR

This paper extends the concept of fluctuation-induced effective interactions to out-of-equilibrium systems, demonstrating how external shaking influences forces between inclusions in soft materials, with potential applications in phase control.

Contribution

It introduces a method to compute and tune forces between objects in driven soft materials, expanding understanding beyond equilibrium Casimir effects.

Findings

Shaking can reverse the sign of forces.

Force magnitude and range depend on shaking specifics.

Potential for controlling phase ordering in soft materials.

Abstract

The concept of fluctuation-induced effective interactions is extended to systems driven out of equilibrium. We compute the forces experienced by macroscopic objects immersed in a soft material driven by external shaking sources. We show that, in contrast with equilibrium Casimir forces induced by thermal fluctuations, their sign, range and amplitude depends on specifics of the shaking and can thus be tuned. We also comment upon the dispersion of these shaking-induced forces, and discuss their potential application to phase ordering in soft-materials.