hydraulic jump

hydraulic jump

Sudden change in water level, analogous to a shock wave, commonly seen below weirs and sluice gates where a smooth stream of water suddenly rises at a foaming front. The fact that the speed of water waves varies with wavelength and with amplitude leads to a wide variety of effects. Tidal bores, which may be observed on some estuaries, are large-scale examples. See also Bernoulli's principle.

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hydraulic jump [hī′drȯ·lik ′jəmp]

(fluid mechanics)

A steady-state, finite-amplitude disturbance in a channel, in which water passes turbulently from a region of (uniform) low depth and high velocity to a region of (uniform) high depth and low velocity; when applied to hydraulic jumps, the usual hydraulic formulas governing the relations of velocity and depth do not conserve energy.

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Hydraulic jump

An abrupt increase of depth in a free-surface liquid flow. A hydraulic jump is characterized by rapid flow and small depths on the upstream side, and by larger depths and smaller velocities on the downstream side. A jump can form only when the upstream flow is supercritical, that is, when the fluid velocity is greater than the propagation velocity c of a small, shallow-water gravity wave (c = gh, where g is the acceleration of gravity and h is the depth). A considerable amount of energy is dissipated in the conversion from supercritical to subcritical flow. See Open channel