The poise (symbol P; ) is the unit of dynamic viscosity (absolute viscosity) in the

centimetre–gram–second system of units The centimetre–gram–second system of units (CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unamb ...

(CGS). It is named after Jean Léonard Marie Poiseuille (see Hagen–Poiseuille equation). The centipoise (1 cP = 0.01 P) is more commonly used than the poise itself. Dynamic viscosity has dimensions of

\mathrm

, that is,

mathsf^1 \mathsf^ \mathsf^/math>. 1~\text = 0.1~\text^  \text  \text^ = 1~\text^  \text  \text^ = 1~\text  \text  \text^. The analogous unit in the

International System of Units The International System of Units, internationally known by the abbreviation SI (from French ), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official s ...

is the

pascal-second Viscosity is a measure of a fluid's rate-dependent resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup h ...

(Pa⋅s):

1~\text  \text = 1~\text  \text  \text^ = 1~\text^  \text  \text^ = 10~\text.

The poise is often used with the

metric prefix A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The pr ...

''centi-'' because the viscosity of water at 20 °C ( standard conditions for temperature and pressure) is almost exactly 1 centipoise. A centipoise is one hundredth of a poise, or one millipascal-second (mPa⋅s) in SI units (1 cP = 10⁻³ Pa⋅s = 1 mPa⋅s). The CGS symbol for the centipoise is cP. The abbreviations cps, cp, and cPs are sometimes seen. Liquid water has a viscosity of 0.00890 P at 25 °C at a pressure of 1

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

(0.00890 P = 0.890 cP = 0.890 mPa⋅s)."Viscosity of Liquids", in CRC Handbook of Chemistry and Physics, 91st Edition, W.M. Haynes, ed., CRC Press/Taylor and Francis, Boca Raton, Florida, 2010-2011.

References

{{CGS units Centimetre–gram–second system of units Units of dynamic viscosity et:Poise

See also

References