Eindhoven University of Technology, the Netherlands
The (dense) suspension of non spherical particles occurs frequently in many different natural and industrial problems alike; examples include biological fluids like blood as well as industrial processes like paper making. For the case of non spherical particles the rheological properties as well as the microscopic structure are not yet well characterised. Typically a strongly directional order (nematic phase) characterise the microstructure and affects as well the macroscopic behaviours. The aim of the present work is to characterise the nematic properties of suspensions formed by ellipsoidal particles in a simple shear flow at vanishing Reynolds number. We present the results of the analysis performed on a dataset obtained by means of Lattice-Boltzmann simulations of fully resolved oblate and prolate particles with aspect ratio 3 at different volume fractions ranging between 0.1 and 0.5. For these aspect ratios both prolate and oblate particles show a strong large-scale directional order measurable by the nematic order parameter. Suspensions formed by prolate particles show also a high bi-axial behavior with two preferential directions, the first almost aligned with the mean flow, the second one with the vorticity direction.