IMO

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Note added at 7 mins (2016-02-26 20:00:06 GMT)
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Settling is the process by which particulates settle to the bottom of a liquid and form a sediment. Particles that experience a force, either due to gravity or due to centrifugal motion will tend to move in a uniform manner in the direction exerted by that force. For gravity settling, this means that the particles will tend to fall to the bottom of the vessel, forming a slurry at the vessel base
https://en.wikipedia.org/wiki/Settling
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In a concentrated suspension, particles settle as a more or less consolidated mass with a sharp boundary between settling suspension and supernatant.
http://www.sciencedirect.com/science/article/pii/S0927775706...
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Settling of Suspensions

The simple batch settling test can supply all the information for the design of a thickener for separation of particles from a liquid. In this test a suspension of particles of known concentration is prepared in a measuring cylinder. The cylinder is shaken to thoroughly mix the suspension and then placed upright to allow the suspension to settle. The positions of the interfaces which form are monitored in time. Two types of settling occur depending on the initial concentration of the suspension. Type 1 settling, in which three zones of constant concentration form is depicted in the video. The top zone is clear liquid. The middle zone has a concentration equal to the initial suspension concentration. The lower zone is the sediment concentration.

http://www.wiley.com/legacy/wileychi/rhodestechnology2e/susp...
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Intrinsic convection in a settling suspension

http://www.damtp.cam.ac.uk/user/hinch/publications/PhysFluid...
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We report direct observations of the structure factor in a settling suspension, using numerical simulations based on a lattice-Boltzmann model of ..
http://journals.aps.org/pre/abstract/10.1103/PhysRevE.69.050...