Effects of volume fraction and particle shape on the rheological properties of oblate spheroid suspensions*

Coupled lattice Boltzmann and discrete element methods were employed to investigate the rheological properties of oblate spheroid suspensions in a Newtonian fluid. The volume fraction of the particles is varied, along with the particle aspect ratio. As the particle shape is varied from sphere to oblate, we observe an increase of the relative viscosity, as well as an increase of the particle contacts and the contact distance. We also report the first and second normal stress difference coefficients as they vary with the volume fraction and/or the particle shape. The more oblate particles in denser suspensions are observed to reorient systematically subject to the shear flow. We recast the viscosity data using the Krieger-Dougherty formula and report the modified Einstein coefficients.