Reynoldsn.

Brit.

/ˈrɛnldz/, U.S.

/ˈrɛnəl(d)z/

Origin: From a proper name. Etymon: proper name Reynolds.

Etymology: < the name of Osbourne Reynolds (1842–1912), Irish engineer and physicist.In Reynolds number n. at sense 1 apparently after German Reynolds'sche Zahl (A. Sommerfeld 1908, in Atti del Congresso Internazionale dei Matematici 3 116).

Physics.

1. Reynolds number n. (also Reynolds' number (now rare)) a dimensionless number used in fluid mechanics to characterize fluid flow past a body or in a duct, having for any given system a critical value above which the flow is turbulent. Symbol Re.Typically evaluated as ^ρvd/ _μ, where ρ is the density of the fluid, v is the speed of the fluid relative to the body or duct, d is a diameter or other characteristic length, and μ is the absolute viscosity of the fluid.In a smooth straight uniform pipe, laminar flow typically occurs for a Reynolds number less than 2000; turbulent flow is typically established for one greater than 3000.

ΘΚΠ

the world > matter > physics > mechanics > fluid mechanics > [noun] > specific numbers or quantities

Reynolds number1910

Weber number1937

magnetic Reynolds number1950

Rayleigh number1950

1910 Sci. Abstr. A. 13 406 The flow..is conditioned by the so-called Reynolds' number.

1932 Science 29 Apr. 468 The data have been correlated with the flow of fluids in circular pipes by plotting a modified Reynolds number against a friction factor.

1958 E. U. Condon & H. Odishaw Handbk. Physics iii. ii. 35/1 For low speeds the Nusselt number is a function of the Reynolds number, the Prandtl (or Péclet) number, and the Grashof number.

1975 Sci. Amer. Nov. 83/1 In a large hummingbird..the mean value of the Reynolds number for the flow past oscillating wings is 15,000.

2003 Y. A. Çengel Heat Transfer (ed. 2) vi. 343 For flow over a flat plate, the generally accepted value of the critical Reynolds number is Re_cr =..5 × 10⁵.

2. Reynolds stress n. a mathematical quantity representing the stress in a fluid arising from turbulence.

ΘΚΠ

the world > matter > physics > mechanics > dynamics > fluid dynamics > [noun] > ratio of transfer of momentum due to turbulence

Reynolds stress1936

1936 Proc. Royal Soc. A. 157 559 The effect of rotation on the Reynolds stress in turbulent motion.

1964 Oceanogr. & Marine Biol. 2 17 The spectrum for k > 0·02 cm⁻¹ could not make a major contribution to the Reynolds stresses.

2005 S. A. Thorpe Turbulent Ocean v. 161 The Reynolds stress is proportional to the square of the wave amplitude.

This entry has been updated (OED Third Edition, March 2010; most recently modified version published online March 2022).

单词	reynolds
释义	Reynoldsn. Brit. /ˈrɛnldz/, U.S. /ˈrɛnəl(d)z/ Origin: From a proper name. Etymon: proper name Reynolds. Etymology: < the name of Osbourne Reynolds (1842–1912), Irish engineer and physicist.In Reynolds number n. at sense 1 apparently after German Reynolds'sche Zahl (A. Sommerfeld 1908, in Atti del Congresso Internazionale dei Matematici 3 116). Physics. 1. Reynolds number n. (also Reynolds' number (now rare)) a dimensionless number used in fluid mechanics to characterize fluid flow past a body or in a duct, having for any given system a critical value above which the flow is turbulent. Symbol Re.Typically evaluated as ^ρvd/ _μ, where ρ is the density of the fluid, v is the speed of the fluid relative to the body or duct, d is a diameter or other characteristic length, and μ is the absolute viscosity of the fluid.In a smooth straight uniform pipe, laminar flow typically occurs for a Reynolds number less than 2000; turbulent flow is typically established for one greater than 3000. ΘΚΠ the world > matter > physics > mechanics > fluid mechanics > [noun] > specific numbers or quantities Reynolds number1910 Weber number1937 magnetic Reynolds number1950 Rayleigh number1950 1910 Sci. Abstr. A. 13 406 The flow..is conditioned by the so-called Reynolds' number. 1932 Science 29 Apr. 468 The data have been correlated with the flow of fluids in circular pipes by plotting a modified Reynolds number against a friction factor. 1958 E. U. Condon & H. Odishaw Handbk. Physics iii. ii. 35/1 For low speeds the Nusselt number is a function of the Reynolds number, the Prandtl (or Péclet) number, and the Grashof number. 1975 Sci. Amer. Nov. 83/1 In a large hummingbird..the mean value of the Reynolds number for the flow past oscillating wings is 15,000. 2003 Y. A. Çengel Heat Transfer (ed. 2) vi. 343 For flow over a flat plate, the generally accepted value of the critical Reynolds number is Re_cr =..5 × 10⁵. 2. Reynolds stress n. a mathematical quantity representing the stress in a fluid arising from turbulence. ΘΚΠ the world > matter > physics > mechanics > dynamics > fluid dynamics > [noun] > ratio of transfer of momentum due to turbulence Reynolds stress1936 1936 Proc. Royal Soc. A. 157 559 The effect of rotation on the Reynolds stress in turbulent motion. 1964 Oceanogr. & Marine Biol. 2 17 The spectrum for k > 0·02 cm⁻¹ could not make a major contribution to the Reynolds stresses. 2005 S. A. Thorpe Turbulent Ocean v. 161 The Reynolds stress is proportional to the square of the wave amplitude. This entry has been updated (OED Third Edition, March 2010; most recently modified version published online March 2022). < n.1910
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