(279a) Microstruture and Rheology In Sheared Suspensions of Anisotropic Dicolloids

Large scale simulations are presented for concentrated suspensions of anisotropic dicolloids. The particles under study consist of composite particles formed from two intersecting spheres of arbitrary radii and center-center spacing. Recent experimental efforts have reported synthesis techniques for such anisotropic dicolloids with sizes ranging from 250 nanometers to several microns. Experiments have suggested a range of interesting phase behavior with order-disorder-order transitions as a function of Pe and volume fraction. In the present study, we use high precision Stokesian dynamic simulations and reduced precision near field lubrication models to study the dynamics of sheared suspensions of these anisotropic particles as a function of volume fraction, interparticle forces and Peclet number. We capture the order-disorder-order transitions reported in experiments and investigate systems with a high degree of positional order and varying degrees of orientational ordering. We show how the degree of particle anisotropy affects the degree and alignment of orientational order relative to the shear, gradient and vorticity axes. We show how the changes in microstructural ordering are related to shear thinning, shear thickening and changes in the normal stress.