Fundamentals on Equilibrium Concentration Curves for Sedimentation and Diffusion of Particles in Fluids (original) (raw)
2000
Solutions for the equilibrium sediment concentration profiles, defined as the situation in which the settling movement of sediment particles is compensated by turbulent diffusion in channel flows, are presented and compared with the classical Rouse profile. In the Rouse solution, the settling velocity is considered independent of the sediment concentration, a very restrictive situation which leads to unrealistic results for
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2015
Solutions for the equilibrium sediment concentration profiles, defined as the situation in which the settling movement of sediment particles is compensated by turbulent diffusion in channel flows, are presented and compared with the classical Rouse profile. In the Rouse solution, the settling velocity is considered independent of the sediment concentration, a very restrictive situation which leads to unrealistic results for the sediment concentration near the bottom of the flow. In this paper, the use of the mass conservation principle permits to obtain a more realistic solution for the equilibrium profiles. It is shown that it is possible to extend the obtained profiles until the bottom of the flow (which simplifies further calculations). Further, considering the result of the momentum equation (potential flow) around a sphere, a nonlinear approximation between the settling velocity and the volumetric concentration of sediment is obtained. It is discussed that nonlinear effects mus...
Sediment transport during unsteady settling in an inclined channel
Journal of Fluid Mechanics, 1987
Settling of a dilute, monodisperse suspension between two inclined, narrowly spaced parallel plates is considered. Effects of sediment motion are accounted for. Lubrication theory and a simplified model for the particle motion lead to a system of two coupled nonlinear hyperbolic equations for the evolution of the two interfaces between clear fluid, suspension and sediment. Two problems are solved: batch settling and the filling of a channel that initially contains clear fluid. In the batch-settling case, the sediment has no major qualitative effect on the motion. In the filling problem, however, effects of sediment are important.
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