(423b) Microstructure of Rigid Rod Suspensions

Nonspherical particles suspended in a continuous liquid phase have a tendency to align because of particle-fluid interactions. In the absence of fluid dynamic couples, spontaneous self-alignment can occur due to excluded volume contraints on rotary Brownian motion. This phenomenon prevents a return-to-isotropy from an anisotropic state. Low-order moments of the rotary Smoluchowski equation are used to explore the influence of the rotary Péclet number on the shear viscosity of the suspension. An algebraic closure for the fourth-order orientation operator in terms of the second-order orientation operator is used to predict the orientation states of the suspension. The mapping satisfies the six-fold symmetry properties the six-fold projection properties of the exact orientation tetradic. The instantaneous orientation states predicted by the theory are realizable for all Peclet numbers and for all excluded volume potentials.

YoChan Kim, André Bénard, and Charles A. Petty, Microstructure and Rheology of Rigid Suspensions, Ind. Eng. Chem. Res., 2015, 54, 4497-4504.