Hyperuniformity with no fine tuning in sheared sedimenting suspensions

TL;DR

This paper demonstrates that in sheared sedimenting suspensions, hyperuniformity naturally emerges at low sedimentation speeds without the need for fine-tuning, extending across large length scales as sedimentation diminishes.

Contribution

It reveals a regime where hyperuniformity occurs automatically in sedimenting suspensions under shear, without fine-tuning of parameters.

Findings

Hyperuniformity appears at low sedimentation speeds.

Homogenization lengthscale diverges as sedimentation speed approaches zero.

Theoretical and simulation results support the natural emergence of hyperuniformity.

Abstract

Particle suspensions, present in many natural and industrial settings, typically contain aggregates or other microstructures that can complicate macroscopic flow behaviors and damage processing equipment. Recent work found that applying uniform periodic shear near a critical transition can reduce fluctuations in the particle concentration across all length scales, leading to a hyperuniform state. However, this strategy for homogenization requires fine tuning of the strain amplitude. Here we show that in a model of sedimenting particles under periodic shear, there is a well-defined regime at low sedimentation speed where hyperuniform scaling automatically occurs. Our simulations and theoretical arguments show that the homogenization extends up to a finite lengthscale that diverges as the sedimentation speed approaches zero.