In
fluid dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) a ...
, the reyn is a British unit of
dynamic viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the int ...
,
named in honour of
Osbourne Reynolds
Osborne Reynolds (23 August 1842 – 21 February 1912) was an Irish-born innovator in the understanding of fluid dynamics. Separately, his studies of heat transfer between solids and fluids brought improvements in boiler and condenser design. ...
, for whom the
Reynolds number
In fluid mechanics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. At low Reynolds numbers, flows tend to be dom ...
is also named.
[Juvinal, Robert C. & Marshek, Kurt M.; ''Fundamentals of machine component design''. 2nd ed., 1991, pp. 480, ]
Conversions
By definition,
:1 reyn = 1 lb
f s in
−2.
It follows that the relation between the reyn and the
poise is approximately
:1 reyn = 6.89476 × 10
4 P.
In
SI units, viscosity is expressed in newton-seconds per square meter, or equivalently in
pascal
Pascal, Pascal's or PASCAL may refer to:
People and fictional characters
* Pascal (given name), including a list of people with the name
* Pascal (surname), including a list of people and fictional characters with the name
** Blaise Pascal, Frenc ...
-seconds. The conversion factor between the two is approximately
:1 reyn = 6890 Pa s.
References
External links
ReynHistory of the unit
Fluid dynamics
Units of dynamic viscosity
{{Fluiddynamics-stub