Memory impairment in flowing suspensions. III. Brownian rotation of spheroids

The transient behavior of a suspension of rigid axisymmetric particles in a shear flow coupled with rotary Brownian diffusion is considered. The orientation distributions of the particles undergo irreversible damped oscillations of frequency twice that of the rotating particles. The rotary Brownian movements of the particles are computer simulated using Monte-Carlo calculations. Empirical equations are suggested for the rate of memory impairment which is shown to be dependent upon the rotary Brownian diffusion coefficient, the equivalent spheroidal axis ratio, and the initial orientations of the particles.