Depletion forces in non-equilibrium

TL;DR

This paper extends the concept of depletion forces to non-equilibrium conditions, revealing forces that violate Newton's third law, are non-conservative, and exhibit anisotropy with both attraction and repulsion.

Contribution

It introduces a generalized framework for depletion forces in flowing baths, highlighting fundamental differences from equilibrium behavior.

Findings

Non-equilibrium depletion forces violate Newton's third law

Forces are non-conservative and anisotropic

Presence of both attractive and repulsive force domains

Abstract

The concept of effective depletion forces between two fixed big colloidal particles in a bath of small particles is generalized to a non-equilibrium situation where the bath of small Brownian particles is flowing around the big particles with a prescribed velocity. In striking contrast to the equilibrium case, the non-equilibrium forces violate Newton's third law, are non-conservative and strongly anisotropic, featuring both strong attractive and repulsive domains.