This thesis presents experimental measurements of the rheological behavior of liquid-solid mixtures at moderate Reynolds (defined by the shear rate and particle diameter) and Stokes numbers, ranging from 3 [less thqan or equa to] Re [less thqan or equa to] 1.6 x 10^3 and 0.4 [less thqan or equa to] St [less thqan or equa to] 195. The experiments use a specifically designed Couette cylindrical rheometer that allows for probing the transition from transporting a pure liquid to transporting a dense suspension of particles. Measurements of the shear stress are presented for a wide range of particle concentration (10 to 60% in volume) and for particle to fluid density ratio between 1 and 1.05. The effective relative viscosity exhibits a strong dependence on the solid fraction for all density ratios tested. For density ratio of 1 the effective viscosity increases with Stokes number (St) for volume fractions (phi) lower than 40% and becomes constant for higher phi. When the particles are denser than the liquid, the effective viscosity shows a stronger dependance on St. An analysis of the particle resuspension for the case with a density ratio of 1.05 is presented and used to predict the local volume fraction where the shear stress measurements take place. When the local volume fraction is considered, the effective viscosity for settling and no settling particles is consistent, indicating that the effective viscosity is independent of differences in density between the solid and liquid phase. Shear stress measurements of pure fluids (no particles) were performed using the same rheometer, and a deviation from laminar behavior is observed for gap Reynolds numbers above 4 x 10^3, indicating the presence of hydrodynamic instabilities associated with the rotation of the outer cylinder. The increase on the effective viscosity with Stokes numbers observed for mixtures with phi [less thqan or equa to] 30% appears to be affected by such hydrodynamic instabilities. The effective viscosity for the current experiments is considerably higher than the one reported in non-inertial suspensions.

This thesis presents experimental measurements of the rheological behavior of liquid-solid mixtures at moderate Reynolds (defined by the shear rate and particle diameter) and Stokes numbers, ranging from 3 [less thqan or equa to] Re [less thqan or equa to] 1.6 x 10^3 and 0.4 [less thqan or equa to] St [less thqan or equa to] 195. The experiments use a specifically designed Couette cylindrical rheometer that allows for probing the transition from transporting a pure liquid to transporting a dense suspension of particles. Measurements of the shear stress are presented for a wide range of particle concentration (10 to 60% in volume) and for particle to fluid density ratio between 1 and 1.05. The effective relative viscosity exhibits a strong dependence on the solid fraction for all density ratios tested. For density ratio of 1 the effective viscosity increases with Stokes number (St) for volume fractions (phi) lower than 40% and becomes constant for higher phi. When the particles are denser than the liquid, the effective viscosity shows a stronger dependance on St. An analysis of the particle resuspension for the case with a density ratio of 1.05 is presented and used to predict the local volume fraction where the shear stress measurements take place. When the local volume fraction is considered, the effective viscosity for settling and no settling particles is consistent, indicating that the effective viscosity is independent of differences in density between the solid and liquid phase. Shear stress measurements of pure fluids (no particles) were performed using the same rheometer, and a deviation from laminar behavior is observed for gap Reynolds numbers above 4 x 10^3, indicating the presence of hydrodynamic instabilities associated with the rotation of the outer cylinder. The increase on the effective viscosity with Stokes numbers observed for mixtures with phi [less thqan or equa to] 30% appears to be affected by such hydrodynamic instabilities. The effective viscosity for the current experiments is considerably higher than the one reported in non-inertial suspensions.

An experimental study of the motion of 100 micron diameter glass and stainless steel spheres in a fully developed turbulent liquid pipe flow was conducted. Furthermore, the liquid, water, was directed vertically downward through a 5.08 cm inside diameter plexiglas tube. One goal was to measure the turbulence properties of the particles in the r-$theta$ plane with a previously developed axial viewing photographic technique. Another goal was to determine the effects of the inherent inhomogeneities of turbulent pipe flow on the results. Several particle turbulence properties were measured. Radial direction Lagrangian and Eulerian particle diffusion coefficients were obtained at Reynolds numbers (based on bulk velocity and pipe diameter) ranging from 15,700 to 141,000. Radial and azimuthal direction particle turbulence intensity profiles for both particles were obtained at Re = 16,000 and 72,000. The technique also permitted the radial and azimuthal direction particle acceleration to be measured. A new phenomenon was discovered which is the result of the inhomogeneities of turbulent pipe flow. It was found that under certain conditions, the particles that diffuse to the pipe wall may get temporarily or permanently trapped there. They get trapped in a patterned manner as well. Inhomogeneities were also found to affect the measured radial direction particle concentration and average velocity profiles, but only under certain conditions.