Operations involving solid-liquid flows play a significant role throughout many industries, including pharmaceutical manufacturing, mining, and oil refining. Unfortunately, the limited understanding of solid-liquid systems results in significant loss in productivity. The development of accurate models that predict the behavior of these solid-liquid systems is needed to improve their design, scale up, and optimization. Non-intrusive flow measurements, where multiple flow variables are measured simultaneously, are needed to develop and validate flow models.

The transition from flow dominated by particle collisions to flow dominated by fluid-particle shear was investigated. Laser Doppler velocimetry (LDV) was used to collect non-intrusive data of the mean and fluctuating velocities of both the solid and liquid components of a turbulent two-phase vertical flow. The velocity and solids concentration of the slurry were varied so that data extended from a collision dominated flow regime to a viscous dominated flow regime. Water and 1 mm soda lime (glass) particles were used and solids concentrations between 0 and 4 percent by volume were investigated over a range of flow velocities. A pilot-scale flow loop made of 3 inch stainless steel pipe, including a vertical test section 60 diameters in height was constructed. The loop was operated at flows of 200 to 600 gpm.

The data collected were compared with predictions from a two-phase flow model which includes a fluctuating energy balance for the particle assembly. The results show the transition from viscous dominated to collision dominated flow as a function of solids concentration and flow velocity. Additionally, the results indicate the importance of the magnitude of the particle impact velocity in the presence of a viscous fluid on accurate prediction of the fluctuating solids velocity.