Dynamics and rheology of periodically driven suspensions

Suspensions of hydrodynamically interacting particles are important model systems for understanding the dynamics of diverse natural and industrial processes, such as the collective motion of bacterial swarms and the potential fabrication of hyperuniform metamaterials. In many cases, the particle motions are externally controlled by a time-dependent flow, so a basic understanding of their dynamics subject to periodic deformations, e.g. an oscillatory shear flow, will have particular reference values. Recent work in the literature have identified two mechanisms for suspensions of spherical particles in oscillatory shear to undergo a dynamical phase transition from being reversible to diffusive, due to either interparticle collision or attraction [1,2]. However, none of the studies has included long-range hydrodynamic interactions, which are always present regardless of the packing density, and may be especially important for the structure relaxation of concentrated suspensions. Here, we numerically examine the suspension network evolution with full hydrodynamic interactions using a newly developed fast Stokesian dynamics method [3]. Rigorous simulations will be used to illustrate the effects of oscillation amplitude and frequency on the stress distribution and microscopic dynamics, highlighting the connection between suspension rheology and self-organization.