You can mark you interesting snippets of text that will be available through a unique link in your browser.


viscosity

Translation
viscosity
/vi skos"i tee/, n., pl. viscosities.
1. the state or quality of being viscous.
2. Physics.
a. the property of a fluid that resists the force tending to cause the fluid to flow.
b. the measure of the extent to which a fluid possesses this property.
[1375-1425; late ME < ML viscositas, equiv. to L viscos(us) VISCOUS + -itas- -ITY]

* * *

Resistance of a fluid to a change in shape, or movement of neighbouring portions relative to one another.

Viscosity denotes opposition to flow. It may also be thought of as internal friction between the molecules. Viscosity is a major factor in determining the forces that must be overcome when fluids are used in lubrication or transported in pipelines. It also determines the liquid flow in spraying, injection molding, and surface coating. The viscosity of liquids decreases rapidly with an increase in temperature, while that of gases increases with an increase in temperature. The SI unit for viscosity is the newton-second per square metre (N-s/m2).

* * *

      resistance of a fluid (liquid or gas) to a change in shape, or movement of neighbouring portions relative to one another. Viscosity denotes opposition to flow. The reciprocal of the viscosity is called the fluidity, a measure of the ease of flow. Molasses, for example, has a greater viscosity than water. Because part of a fluid that is forced to move carries along to some extent adjacent parts, viscosity may be thought of as internal friction between the molecules; such friction opposes the development of velocity differences within a fluid. Viscosity is a major factor in determining the forces that must be overcome when fluids are used in lubrication and transported in pipelines. It controls the liquid flow in such processes as spraying, injection molding, and surface coating.

      For many fluids the tangential, or shearing, stress (shear stress) that causes flow is directly proportional to the rate of shear strain, or rate of deformation, that results. In other words, the shear stress divided by the rate of shear strain is constant for a given fluid at a fixed temperature. This constant is called the dynamic, or absolute, viscosity and often simply the viscosity. Fluids that behave in this way are called Newtonian fluids in honour of Sir Isaac Newton (Newton, Sir Isaac), who first formulated this mathematical description of viscosity.

      The viscosity of liquids decreases rapidly with an increase in temperature; the viscosity of gases increases with an increase in temperature. Thus, upon heating, liquids flow more easily, whereas gases flow more sluggishly.

      The dimensions of dynamic viscosity are force times time divided by area. The unit of viscosity, accordingly, is newton-second per square metre.

      For some applications the kinematic viscosity is more useful than the absolute, or dynamic, viscosity. Kinematic viscosity is the absolute viscosity of a fluid divided by its mass density. (Mass density is the mass of a substance divided by its volume.) The dimensions of kinematic viscosity are area divided by time; the appropriate units are metre squared per second. The unit of kinematic viscosity in the centimetre-gram-second (CGS) system, called the stokes in Britain and the stoke in the U.S., is named for the British physicist Sir George Gabriel Stokes (Stokes, Sir George Gabriel, 1st Baronet). The stoke is defined as 1 cm squared per second.

* * *


Universalium. 2010.

Synonyms:

  
Share  

Look at other dictionaries:

  • viscosity — noun вязкость, липкость, клейкость; тягучесть …   Англо-русский словарь Мюллера

  • Viscosity — Vis*cos i*ty, n. [Cf. F. viscosit[ e], LL. viscositas.] 1. The quality or state of being viscous. [1913 Webster] 2. (Physics) A property possessed by a viscous fluid, being a resistance to the forces causing a fluid to flow, caused by… …   The Collaborative International Dictionary of English

  • viscosity — 1> вязкость, липкость; тягучесть 2> физ. (динамическая) вязкость, внутреннее трение …   Новый большой англо-русский словарь

  • viscosity — n вязкость absolute viscosity bulk viscosity Engler viscosity kinematic viscosity reciprocal viscosity Saybolt viscosity Англо русский строительный словарь. М.: Русский Язык …   Англо-русский словарь строительных терминов

  • viscosity — index adhesion (affixing) Burton s Legal Thesaurus. William C. Burton. 2006 …   Law dictionary

  • Viscosity — For other uses, see Viscosity (disambiguation). Viscosity The substance above has lower viscosity than the substance below SI symbol: μ, η SI unit: Pa·s  …   Wikipedia

  • viscosity — 1) вязкость, внутреннее трение 2) коэффициент вязкости 3) вязкое вещество • absolute viscosity anomalous viscosity apparent viscosity Brookfield viscosity bulk viscosity characteristic viscosity dilatational viscosity dynamic viscosity eddy… …   Англо-русский словарь технических терминов

  • viscosity — 1) вязкость 2) вязкостный 3) тягучесть – coefficient of viscosity – eddy viscosity – elastic viscosity – intrinsic viscosity – kinematic viscosity – Newtonian viscosity – non Newtonian viscosity – of low …   Англо-русский технический словарь

  • viscosity — вязкость; внутреннее трение; тягучесть absolute viscosity anomalous viscosity apparent viscosity bit viscosity dynamic viscosity effective viscosity Engler viscosity …   Англо-русский словарь нефтегазовой промышленности

  • viscosity — noun (plural ties) Etymology: Middle English viscosite, from Anglo French viscosité, from Medieval Latin viscositat , viscositas, from Late Latin viscosus viscous Date: 14th century 1. the quality or state of being viscous 2. the property of… …   New Collegiate Dictionary