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Hydraulic jump in a rectangular channel, also known as classical jump, is a natural phenomenon that occurs whenever flow changes from supercritical to subcritical flow. In this transition, the water surface rises abruptly, surface rollers are formed, intense mixing occurs, air is entrained, and often a large amount of energy is dissipated.
A diagram showing the relationship for flow depth (y) and total Energy (E) for a given flow (Q). Note the location of critical flow, subcritical flow, and supercritical flow. The energy equation used for open channel flow computations is a simplification of the Bernoulli Equation (See Bernoulli Principle ), which takes into account pressure ...
In practice, most weirs are low-order polynomial weirs. The standard rectangular weir is, for example, a polynomial weir of order zero. The triangular (V-notch) and trapezoidal weirs are of order one. High-order polynomial weirs are providing wider range of Head-Discharge relationships, and hence better control of the flow at outlets of lakes ...
The geometry of a weir dictates the coefficient of discharge that passes through the crest, which is proportional to the nappe formation. [9] Engineers solve for the amount of discharge and the cross sectional area of a river to calculate the adequate shape of the weir that should be implemented.
The depth changes abruptly over a comparatively short distance. Rapidly varied flow is known as a local phenomenon. Examples are the hydraulic jump and the hydraulic drop. Gradually-varied flow. The depth changes over a long distance. Continuous flow. The discharge is constant throughout the reach of the channel under consideration. This is ...
Williams, Gardner Stewart; Hazen, Allen (1920), Hydraulic tables: the elements of gagings and the friction of water flowing in pipes, aqueducts, sewers, etc., as determined by the Hazen and Williams formula and the flow of water over sharp-edged and irregular weirs, and the quantity discharged as determined by Bazin's formula and experimental ...
Figure 4: An undular front on a tidal bore. At this point the water is relatively deep and the fractional change in elevation is small. A tidal bore is a hydraulic jump which occurs when the incoming tide forms a wave (or waves) of water that travel up a river or narrow bay against the direction of the current. [16]
Using this term, one can calculate many things in the same way as for a round tube. When the cross-section is uniform along the tube or channel length, it is defined as [1] [2] =, where A is the cross-sectional area of the flow, P is the wetted perimeter of the cross-section.