Slurry transport, the concentration distribution: A continuing study

In previous publications, an analytical model was presented for the concentration distribution of small particles in slurry flow. This model assumes that the advection diffusion equation is valid, and the model uses a diffusivity based on the Limit Deposit Velocity. This means particles follow the turbulent eddies and at the LDV the bottom concentration is high enough to form a bed. Further research has shown that the bed concentration at the LDV must be related to a maximum bed concentration and that the hindered settling equation must be modified. This paper will give an improved concentration distribution model, including a model for the bed concentration at the Limit Deposit Velocity (LDV) and a new hindered settling model. The new model is validated with experimental data of Roco & Shook, Gillies, Kaushal & Tomita and Matousek for both real sand particles and glass beads. The model is also compared with CFD (Euler-Euler) calculations and gives a good resemblance. Differences (near the pipe wall) are highlighted. All in all, the new model gives very good results over a broad range of particle diameters (0.09-2.4 mm), pipe diameters (2 inch to 20 inch) and concentrations up to 40%.