Institute of Fundamental Technological Research

Short-time dynamic properties of concentrated suspensions of colloidal core-shell particles have been recently studied [1] using a precise force multipole method which accounts for many-particle hydrodynamic interactions (HIs). A core-shell particle is composed of a rigid, spherical dry core of radius a surrounded by an uniformly permeable shell of outer radius b and hydrodynamic penetration depth κ-1. The solvent flow inside the permeable shell is described by the Brinkman-Debye-Bueche equation, and outside the particles by the Stokes equation. The particles are assumed to interact non-hydrodynamically by a hard-sphere no-overlap potential of radius b. Numerical results are presented for the high-frequency shear viscosity, sedimentation coefficient and the short-time translational and rotational self-diffusion coefficients. The simulation results cover the full three-parametric fluid-phase space of the composite particle model, with the volume fraction extending up to 0.45, and the whole range of values for κb, and a/b. Many-particle hydrodynamic interaction effects on the transport properties are explored, and the hydrodynamic influence of the core in concentrated systems is discussed.

Stokes equations, Brinkman-Debye-Bueche equations, permeable particles, translational and rotational self-diffusion, sedimentation, effective viscosity