Sediment particle settling velocity (1)

Описание: In a fluid at rest, a suspended sediment particle falls because it is heavier than water: i.e., it has a downward vertical motion. The terminal fall velocity is the particle settling velocity at equilibrium, when the sum of the gravity force, buoyancy force and fluid drag force are equal to zero. In open channel flows, the particle fall velocity is further affected by the flow turbulence and the interactions with surrounding particles.
Considering a sediment particle settling in a still fluid, the forces acting on the solid particle are: (a) the drag force, (b) the weight force , and (c) the buoyant force. The buoyant force on a submerged body is the difference between the vertical component of pressure force on its underside and the vertical pressure component on its upperside. It counteracts the pressure force and equals the weight of displaced liquid.

The settling velocity of sediment particles is a key physical property, used in particular to predict the onset of sediment suspension and suspended sediment transport rate. The present development is focused on the terminal velocity of a single particle. In real fluid flows, the effects of sediment concentration and turbulence are relevant (Chanson 2004a, pp. 164-165). All these are discussed in a number of relevant Youtube video movies in the same Playlist at:
{   / @hubert_chanson  }

Fluid mechanics and hydraulics in Hubert Chanson Youtube channel {   / @hubert_chanson  }
Fundamentals of open channel hydraulics [Playlist]
Advanced hydraulics of open channel flows [Playlist]
Sediment transport in open channel [Playlist]
Environmental hydraulics of open channel flows [Playlist]

Shear velocity
Shear Reynolds number

References
ENGELUND, F., and HANSEN, E. (1972). "A Monograph on Sediment Transport in Alluvial Streams." Teknisk Forlag, Copenhagen, Denmark, 3rd edition, 62 pages.
NIELSEN, P. (1992). "Coastal Bottom Boundary Layers and Sediment Transport." Advanced Series on Ocean Eng., Vol. 4, World Scientific Publ., Singapore.
CHANSON, H. (2004a). "The Hydraulics of Open Channel Flow: An Introduction." Butterworth-Heinemann, 2nd edition, Oxford, UK, 630 pages (ISBN 978 0 7506 5978 9).
CHANSON, H. (2004b). "Environmental Hydraulics of Open Channel Flows." Elsevier-Butterworth-Heinemann, Oxford, UK, 483 pages (ISBN 978 0 7506 6165 2).
CHANSON, H. (2014). "Applied Hydrodynamics: An Introduction." CRC Press, Taylor & Francis Group, Leiden, The Netherlands, 448 pages & 21 video movies (ISBN 978-1-138-00093-3).