Settling


Settling

Settling is the process by which particulates settle to the bottom of a liquid and form a sediment.

Settling velocity or fall velocity or terminal velocity (ws) of a (sediment) particle is the at which the sediment settles in still fluid. It is diagnostic of grain size, but is also sensitive to the shape (roundness and sphericity) and density of the grains as well as to the viscosity and density of the fluid. It integrates all of these into a key transport parameter.

For dilute suspensions, Stokes' Law predicts the settling velocity of small spheres in fluid, either air or water. Stokes' Law finds many applications in the natural sciences, and is given by:

:w=frac{2( ho_p- ho_f)gr^2}{9mu}

where "w" is the settling velocity, "ρ" is density (the subscripts "p" and "f" indicate particle and fluid respectively), "g" is the acceleration due to gravity, "r" is the radius of the particle and "μ" is the dynamic viscosity of the fluid.

Stokes' law applies when the Reynolds number is less than 0.1.

Settleable solids are the particulates that settle out of a still fluid. Settleable solids can be quantified for a suspension using an Imhoff tank or cone.

"Settling tanks" are used for separating solids and/or oil from another liquid. In food processing, the vegetable is crushed and placed inside of a settling tank with water. The oil floats the top of the water then is collected. In water and waste water treatment a flocculant is often added prior to settling to form larger particles that settle out quickly in a settling tank leaving the water with a lower turbidity.

Winemaking

In winemaking, the French term for this process is "débourbage". This step usually occurs in white wine production before the start of fermentation. J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 223 Oxford University Press 2006 ISBN 0198609906 ]

ee also

*Sedimentation
*Settling basin
*Total suspended solids
*Suspension (chemistry)

External links

* [http://www.ne-wea.org/LabManual/settleable_solids.htm Settleable solids methodology]
* [http://www.vincentcorp.com/tech_papers/issue140.html Imhoff cone]
* [http://www.ajdesigner.com/phpstokeslaw/stokes_law_terminal_velocity.php Stokes Law terminal velocity calculator]


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  • Settling — Set tling, n. 1. The act of one who, or that which, settles; the act of establishing one s self, of colonizing, subsiding, adjusting, etc. [1913 Webster] 2. pl. That which settles at the bottom of a liquid; lees; dregs; sediment. Milton. [1913… …   The Collaborative International Dictionary of English

  • settling — settling; un·settling; …   English syllables

  • Settling — Settling. См. отстаивание. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • settling — index conclusion (determination) Burton s Legal Thesaurus. William C. Burton. 2006 …   Law dictionary

  • settling — /set ling, l ing/, n. 1. the act of a person or thing that settles. 2. Usually, settlings. sediment. [1400 50; late ME; see SETTLE1, ING1] * * * In building construction, the gradual subsiding of a structure as the soil beneath its foundation… …   Universalium

  • settling — nusėdimas statusas T sritis fizika atitikmenys: angl. sedimentation; settling; settling down vok. Absetzen, n; Sedimentation, f rus. оседание, n pranc. sédimentation, f …   Fizikos terminų žodynas

  • Settling — Settle Set tle, v. t. [imp. & p. p. {Settled}; p. pr. & vb. n. {Settling}.] [OE. setlen, AS. setlan. [root]154. See {Settle}, n. In senses 7, 8, and 9 perhaps confused with OE. sahtlen to reconcile, AS. sahtlian, fr. saht reconciliation, sacon to …   The Collaborative International Dictionary of English

  • settling — sluoksniavimasis statusas T sritis chemija apibrėžtis Išsiskirstymas sluoksniais. atitikmenys: angl. delamination; exfoliation; foliation; lamination; settling; splitting; stratification rus. расслаивание; расслоение …   Chemijos terminų aiškinamasis žodynas

  • settling — nusistojimas statusas T sritis chemija apibrėžtis Nuosėdų savaiminis atsiskyrimas iš nejudinamos suspensijos. atitikmenys: angl. settling rus. отстаивание …   Chemijos terminų aiškinamasis žodynas

  • settling — noun Date: 1594 sediment, dregs usually used in plural …   New Collegiate Dictionary


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