Settling Characteristics of Sediments in Moving Bingham Fluid

This paper investigates the effect of velocity on the settling characteristics of coarse particles in a moving Bingham fluid. The experiments conducted in a recirculating pipeline show that the thickness of the deposited coarse particles contained in the Bingham fluid increases when the flow starts to move. The increase continues until a critical velocity, beyond which the thickness of deposition decreases. When the velocity is further increased to another critical value, all the particles in the flow are suspended. Further analysis of the concentration distribution of coarse particles shows that the Bingham structure is affected by the flow condition. For fluids with a low fine particle concentration, a small velocity (turbulence) increases the Bingham yield stress, resulting in a reduction of the settling velocity of the coarse particles. A high velocity (turbulence) destroys the Bingham structure of the fluid and increases coarse particle settlement. For flows with higher fine sediment concentration, the velocity (turbulence) weakens or destroys the Bingham structure and the settling velocity of coarse particles increases.