Rheology of a dilute suspension of Brownian thin disklike particles in a turbulent channel flow

The orientation distribution of tiny Brownian oblate spheroidal particles suspended in a turbulent channel flow along with their generated non-Newtonian stresses are studied numerically. The direct numerical simulation of turbulent channel flow is coupled with a direct Monte-Carlo simulator for the particles conformation. The effects of particle shape factor and the intensity of rotary Brownian motion on the rheology of the suspension are studied. The root-mean-square of non-Newtonian stress fluctuations is computed and discussed. It is found that thinner disks produce higher stresses than thicker disks. Thin disks result in significantly higher normal stress differences. A significant level of shear stress adjacent to the wall is observed for thicker disks, which suggests a significant stress deficit for a suspension of such particles. Unlike rod-like particles, the level of shear stress is always higher than the normal stress differences for disks. It means that the shear viscosity of suspension is always more significant than its extensional viscosity.