Rheological Behavior of Suspensions of Randomly Oriented Rods: 3, Viscometer for Opaque Suspensions.

摘要

With falling-ball rheometry, we have measured the apparent relative viscosity of suspensions of large, neutrally buoyant, rigid rods in a viscous Newtonian fluid, while approximately maintaining the rods in a randomly oriented configuration. A new technique for measuring the time of flight of a ball between two positions is used. This technique, based on an eddy-current detector, enables us to determine the position of a metallic (non-magnetic) ball falling through an opaque suspension, with an estimated inaccuracy of less than 1.5%. An electric signal, which peaks when the ball passes through the plane of the magnetic field, and the elapsed time are recorded using a computerized data acquisition system. The viscosities of two suspensions of different aspect ratio rods are compared at a particle volume fraction of 0.05. (ERA citation 13:049454)