Hydrodynamic interactions can induce jamming in flow-driven systems

TL;DR

This paper reveals that hydrodynamic interactions in flow-driven systems can cause jamming, reducing particle transport across barriers, contrasting with their known role in facilitating force-driven motion, supported by experiments and theory.

Contribution

It demonstrates that hydrodynamic interactions hinder transport in flow-driven systems, a reversal of their effect in force-driven systems, supported by combined experimental and theoretical analysis.

Findings

Hydrodynamic interactions cause jamming in flow-driven colloidal systems.

Particle currents decrease with density at large barriers.

Theoretical model explains jamming as hydrodynamic interaction effect.

Abstract

Hydrodynamic interactions between fluid-dispersed particles are ubiquitous in soft matter and biological systems and they give rise to intriguing collective phenomena. While it was reported that these interactions can facilitate force-driven particle motion over energetic barriers, here we show the opposite effect in a flow-driven system, i.e. that hydrodynamic interactions hinder transport across barriers. We demonstrate this result by combining experiments and theory. In the experiments, we drive colloidal particles using rotating optical traps, thus creating a vortex flow in the corotating reference frame. We observe a jamming-like decrease of particle currents with density for large barriers between traps. The theoretical model shows that this jamming arises from hydrodynamic interactions between the particles. The impact of hydrodynamic interactions is reversed compared to force-driven motion, suggesting that our findings are a generic feature of flow-driven transport.