On the hindered settling of sand-mud suspensions

• Published in: Ocean dynamics 2017-04, Vol.67 (3-4), p.465-483
• Main Authors: Spearman, Jeremy, Manning, Andrew J.
• Format: Article
• Language: English
• Subjects: Atmospheric Sciences; Belgium 7-11 September 2015; Chemical engineering; Debris flow; Earth and Environmental Science; Earth Sciences; Fluid- and Aerodynamics; Geophysics/Geodesy; Marine; Mathematical models; Monitoring/Environmental Analysis; Mud; Oceanography; Permeability; Sand; Sediments; Settling behavior; Slurries; Studies; Topical Collection on the 13th International Conference on Cohesive Sediment Transport in Leuven
• ISSN: 1616-7341; 1616-7228
• DOI: 10.1007/s10236-017-1034-7

Hindered settling, the process by which the settling of sediment particles becomes impeded due to the proximity of other sediment particles, can be an important process for the coastal modeller, especially in highly muddy environments. It is also a significant process in other disciplines such as chemical engineering, the modelling of debris flow, the study of turbidites, piping of slurries and the understanding of processes occurring within a dredger hopper. This study first examines the hindered settling behaviour of monodisperse suspensions in order to create a framework for polydisperse hindered settling that works for both non-cohesive and cohesive suspensions. The Richardson–Zaki equation is adapted to make it compatible with the changes with viscosity that occur near the point at which suspensions become solid. The modified monodisperse settling equation is then compared to data for hindered settling of cohesive suspensions and shown to be consistent with the transition between hindered settling and the initial permeability phase of consolidation. Based on the monodisperse framework developed initially, this paper proposes a hindered settling model for sand/mud mixtures which is based on a modification of the Masliyah ( 1979 ) and Lockett and Bassoon ( 1979 ) hindered settling equation. The model is shown to reproduce the hindered settling of a variety of different sediment mixtures whilst reducing the extent of empiricism often associated with the modelling of polydisperse hindered settling of mud/sand mixtures.