Apparent viscosity of suspensions of rods using falling ball rheometry

Falling ball rheometry measurements of the apparent relative viscosity of s uspensions of randomly oriented rodlike particles are reported for rods hav ing a wide range of aspect ratios and concentrations. These data, combined with those from earlier studies [Milliken , J. Fluid Mech. 202, 217 (1989); Powell , J. Rheology 33, 1173 (1989)], provide a master curve describing t he apparent viscosity in terms of a single parameter, nL(3), where L is the length of the particle and n is the number density. (C) 2001 American Inst itute of Physics.