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Sedimentation of Particles from a Finite Volume Horizontal Buoyant Jet

Author(s): Christopher P. Mclarnon; Peter A. Davies

Linked Author(s): Peter A. Davies

Keywords: Wastewater; Buoyant jet; Sedimentation

Abstract: The results of a series of laboratory model experiments are described for the case of a finite-time, finite-volume discharge of a sediment-laden, turbulent, horizontal buoyant jet of source density ρ e into quiescent homogeneous receiving waters of density (ρ a) and depth H. Parametric experiments have been carried out to determine the spatial and temporal pattern of sedimentation for a range of values of modified gravitational acceleration g′ (=g (ρ a -ρ e) /ρ a), particle sizes d, particle densities ρ s, source discharge rates q 0 and discharge times τ from a two-dimensional source of width b. Data are presented to show that the sedimentation process following cessation of discharge consists of three phases, the relative durations of which are determined primarily by the specific momentum M and buoyancy B fluxes of the discharge, the fall velocity w s of the particles and the durationτof the discharge. Distributions of associated bottomdeposition patterns of sediment have been determined and quantified in terms of the distance x pn from the source to the n points of maximum deposition. Attempts to scale the spatial distributions of sedimentation deposition in terms of the momentum length scale M/B 2/3 of the discharge and the buoyancy/sedimentation length scale w s 2 /g′are shown to be successful for the two primary peaks at x p1 and x p2 in the bottom sediment distributions. The effect of discharge duration timeτupon such scalings is demonstrated.


Year: 1999

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