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A polynomial weir is a weir that has a geometry defined by a polynomial equation of any order n. [11] 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 ...
For channels of a given width, the hydraulic radius is greater for deeper channels. In wide rectangular channels, the hydraulic radius is approximated by the flow depth. The hydraulic radius is not half the hydraulic diameter as the name may suggest, but one quarter in the case of a full pipe. It is a function of the shape of the pipe, channel ...
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.
In rectangular channel, such conservation equation can be further simplified to dimensionless M-y equation form, which is widely used in hydraulic jump analysis in open channel flow. Jump height in terms of flow Dividing by constant and introducing the result from continuity gives
These final two equations are very similar to the Q = CH a n equations that are used for Parshall flumes. In fact, when looking at the flume tables, n has a value equal to or slightly greater than 1.5, while the value of C is larger than (3.088 b 2 ) but still in a rough estimation.
In the National Engineering Handbook, Section 14, Chute Spillways (NEH14), [5] flow equations are given for straight inlets and box inlets. NEH14 provides the following discharge-head relationship for straight inlets of chute spillways, which is given by the flow equation for a weir:
The Chézy Formula is a semi-empirical resistance equation [1] [2] which estimates mean flow velocity in open channel conduits. [3] The relationship was conceptualized and developed in 1768 by French physicist and engineer Antoine de Chézy (1718–1798) while designing Paris's water canal system.
The equation is = / where: Q is the discharge in cubic feet per second over the weir, L is the length of the weir in feet, and h 1 is the height of the water above the top of the weir. [14] [15] [further explanation needed]