born Aug. 23, 1842, Belfast, Ire.
died Feb. 21, 1912, Watchet, Somerset, Eng.
British engineer and physicist.
Educated at Cambridge University, he became the first professor of engineering at the University of Manchester (1868). Best known for his work in hydraulics and hydrodynamics, he formulated the law of resistance in parallel channels (1883), the theory of lubrication (1886), and the standard mathematical framework used in turbulence work (1889). He studied wave engineering and tidal motions in rivers and made pioneering contributions to the concept of group velocity. The Reynolds stress in fluids with turbulent motion and the Reynolds number are named for him.