Definition of Reynolds number in English:

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Reynolds number

Pronunciation: /ˈrɛn(ə)ldz/


A dimensionless number used in fluid mechanics to indicate whether fluid flow past a body or in a duct is steady or turbulent.
Example sentences
  • Small objects have lower Reynolds numbers - a dimensionless quantity proportional to the ratio of the product of the size and flow speed to viscosity.
  • He spoke on boundary layer theory, in particular flows at high Reynolds numbers, in his inaugural lecture in London.
  • For the purpose of biological fluid dynamics, scale is represented by the dimensionless Reynolds number, a ratio that reflects the influence of inertial relative to viscous forces.


Early 20th century: named after Osborne Reynolds (1842–1912), English physicist.

For editors and proofreaders

Line breaks: Rey|nolds num¦ber

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