Hyperuniformity with no fine tuning in sheared sedimenting suspensions

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 length scale that diverges as the sedimentation speed approaches zero.

Effective elastic wave characteristics of composite media

“…In figure 2, we compare the simulation results to the predictions from the strong-contrast approximations [Eqs. (43) and (44) for local approximations, and Eqs. (51) and (52) for the nonlocal counterparts] as well as the Gaunaurd-Überall approximation (GUA) [(B.1) and (B.2)].…”

“…Disordered hyperuniform systems are exotic states of matters that lie between crystals and liquids; they behave like crystals in the way they suppress large-scale density fluctuations and yet are like liquids because they are statistically isotropic without any Bragg peaks [33,34,35]. Hyperuniform systems have attracted considerable attention over the last decade because of their close connections to a broad spectrum of topics that arise in physical [29,35,36,37,38,39,40,41,42,43,44,45,46,47,48], mathematical [49,50,51], and materials sciences [28,52,53,54,55] as well as the emerging § Keller's approximation is derived for the simplified case in which only longitudinal waves propagate in a very special system: colloidal suspensions of spherical particles in which the fluid has zero shear modulus. Such systems can be treated with the scalar Helmholtz equation, which is to be contrasted with our treatment of the full elastodynamic equations for macroscopically anisotropic media.…”

“…Comparison of the predictions of the local strong-contrast approximations [Eqs (43). and(44)], the nonlocal variants [Eqs (51).…”

Over 65% sunlight absorption in a 1 μm Si slab with hyperuniform texture

“…Hyperuniform disorded (HUD) media are statistically isotropic and possess a constrained randomness such that density fluctuations on large scales behave more like those of ordered solids, rather than those of conventional amorphous materials. [27][28][29][30] HUD patterns naturally arise in many physical systems, from the mass distribution in the early universe, 31 structure of prime numbers, 32 hydrodynamics, 33 structure of amorphous ices, 34 sheared sedimenting suspensions, 35 to wave localisation 36 or colloidal packing. 37 When translated into photonic materials, HUDs exhibit large and robust photonic band gaps as in photonic crystals, but are both complete and isotropic.…”

Dynamical arrest of topological defects in 2D hyperuniform disk packings

“…Such correlations are contrasted with typical disordered systems in which pair correlations decay exponentially fast. Moreover, in dynamical systems, hyperuniformity has been observed in particle suspensions, where the application of periodic shear can suppress fluctuations in particle concentration across all length scales leading to a hyperuniform state [9].…”