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'''Viscosity''' is a measure of the [[resistance]] of a fluid which is being deformed by either shear [[stress]] or extensional stress. In everyday terms (and for fluids only), viscosity is "thickness". Thus, [[water]] is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. Viscosity describes a fluid's internal resistance to [[flow]] and may be [[thought]] of as a [[measure]] of fluid friction. For example, high-viscosity magma will [[create]] a tall, steep stratovolcano, because it cannot flow far before it cools, while low-viscosity lava will create a wide, shallow-sloped shield volcano. Put [[Simplicity|simply]], the less viscous something is, the greater its ease of [[movement]] (fluidity). [1] All real fluids (except [http://en.wikipedia.org/wiki/Superfluid superfluids]) have some resistance to stress, but a fluid which has no resistance to shear stress is known as an [[ideal]] fluid or inviscid fluid. The study of viscosity is known as [http://en.wikipedia.org/wiki/Rheology rheology].

'''Viscosity''' is a measure of the [[resistance]] of a fluid which is being deformed by either shear [[stress]] or extensional stress. In everyday terms (and for fluids only), viscosity is "thickness". Thus, [[water]] is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. Viscosity describes a fluid's internal resistance to [[flow]] and may be [[thought]] of as a [[measure]] of fluid friction. For example, high-viscosity magma will [[create]] a tall, steep stratovolcano, because it cannot flow far before it cools, while low-viscosity lava will create a wide, shallow-sloped shield volcano. Put [[Simplicity|simply]], the less viscous something is, the greater its ease of [[movement]] (fluidity). [1] All real fluids (except [https://en.wikipedia.org/wiki/Superfluid superfluids]) have some resistance to stress, but a fluid which has no resistance to shear stress is known as an [[ideal]] fluid or inviscid fluid. The study of viscosity is known as [https://en.wikipedia.org/wiki/Rheology rheology].

==Etymology==

==Etymology==

The word "viscosity" derives from the [[Latin]] word "viscum" for mistletoe. A viscous glue was made from mistletoe berries and used for lime-twigs to catch birds.[2]

The word "viscosity" derives from the [[Latin]] word "viscum" for mistletoe. A viscous glue was made from mistletoe berries and used for lime-twigs to catch birds.[2]

* Massey, B. S. (1983). Mechanics of Fluids (Fifth ed.). Van Nostrand Reinhold (UK). ISBN 0-442-30552-4.  

* Massey, B. S. (1983). Mechanics of Fluids (Fifth ed.). Van Nostrand Reinhold (UK). ISBN 0-442-30552-4.  

== External links ==

== External links ==

*[http://www.engineersedge.com/fluid_flow/fluid_data.htm Fluid Characteristics Chart] A table of viscosities and vapor pressures for various fluids

*[https://www.engineersedge.com/fluid_flow/fluid_data.htm Fluid Characteristics Chart] A table of viscosities and vapor pressures for various fluids

* [http://web.ics.purdue.edu/~alexeenk/GDT/index.html Gas Dynamics Toolbox] Calculate coefficient of viscosity for mixtures of gases  

* [https://web.ics.purdue.edu/~alexeenk/GDT/index.html Gas Dynamics Toolbox] Calculate coefficient of viscosity for mixtures of gases  

* [http://glassproperties.com/viscosity/ViscosityMeasurement.htm Glass Viscosity Measurement] Viscosity measurement, viscosity units and fixpoints, glass viscosity calculation

* [https://glassproperties.com/viscosity/ViscosityMeasurement.htm Glass Viscosity Measurement] Viscosity measurement, viscosity units and fixpoints, glass viscosity calculation

* [http://www.diracdelta.co.uk/science/source/k/i/kinematic%20viscosity/source.html Kinematic Viscosity] conversion between kinematic and dynamic viscosity.  

* [https://www.diracdelta.co.uk/science/source/k/i/kinematic%20viscosity/source.html Kinematic Viscosity] conversion between kinematic and dynamic viscosity.  

* [http://www.thermexcel.com/english/tables/eau_atm.htm Physical Characteristics of Water] A table of water viscosity as a function of temperature

* [https://www.thermexcel.com/english/tables/eau_atm.htm Physical Characteristics of Water] A table of water viscosity as a function of temperature

* [http://trajectory.berlios.de Project Trajectory] Java Web Start Application for simulation of moving bodies through different and user definable media.

* [https://trajectory.berlios.de Project Trajectory] Java Web Start Application for simulation of moving bodies through different and user definable media.

* [http://www.iop.org/EJ/abstract/0953-8984/12/46/305 Vogel–Tammann–Fulcher Equation Parameters]

* [https://www.iop.org/EJ/abstract/0953-8984/12/46/305 Vogel–Tammann–Fulcher Equation Parameters]

* [http://ddbonline.ddbst.de/VogelCalculation/VogelCalculationCGI.exe Calculation of temperature-dependent dynamic viscosities for some common components]

* [https://ddbonline.ddbst.de/VogelCalculation/VogelCalculationCGI.exe Calculation of temperature-dependent dynamic viscosities for some common components]

[[Category: Physics]]

[[Category: Physics]]