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Which of the following conditions are applicable for critical flow
For a critical flow:
The Chezy’s constant C in the Chezy’s equation for mean velocity in open channels is
Chezy’s equation, V =
Substituting dimensions of each term in above equation.
The conveyance K of a channel is a measure of its carrying capacity. In terms of K, the discharge Q is given by
Conveyance K = 1/n(AR2/3). It expresses the discharge capacity of the channel per unit longitudinal slope.
A steady discharge of 1 cumec flows uniformly in a rectangular channel 1 m wide at a depth of 250 mm. The slope of the channel bed is
Critical depth of flow :
q = Q/B = 1
⇒ Yc = 0.467
Yc = 0.5
And normal depth of flow = yn = 0.25 m
since yn < yc therefore channel has steep slope.
In case of a hydraulic jump in a rectangular channel, the post jump, depth d2, when Froude number F1 is √3 , is
where d1 = pre-jump depth
The flow characteristic before and after a hydraulic jump are such that:
The loss of energy in a hydraulic jump leads to unequal specific energies at downstream and upstream sections.
The figure below shows a gradually varied flow situation in an open channel with a break in bed slope. Types of water surface profiles occurring from left to right are
The sequent depth ratio in a. hydraulic jump formed in a horizontal rectangular channel is 16.48. The Froude number of the supercritical stream is
An open channel carries water with a velocity of 0.605 m/s. If the average bed shear stress is 1.0 N/m2, then the Chezy’s constant C is equal to
As we know,
Dividing (i) by (ii) we get,
The Chezy’s and Manning’s formulae are related by
The Manning’s n, Chezy’s C and Darcy-Weisbach’s 'f' are related as,
Open channel flow is the one in which
Flow in a conduit with a free surface is known as open channel flow, flows in irrigation channels, streams and rivers, navigation channels, drainage channels and severs are some examples of open channel flow.
In a subdritica! flow, as the specific energy in a channel is decreased, the depth of flow
If the specific energy at the upstream section of a rectangular channel is 3 m and minimum specific energy is 2.5 m, the maximum height of jump without causing afflux will be
If the Froude’s number before a hydraulic jump occurring in a rectangular horizontal channel is √10 then the Froude’s number after the jump will be
Least possible value of correction factor for
1. kinetic energy is zero
2. kinetic energy is 1
3. momentum is zero
4. momentum is 1
The correct statements are
If velocity is zero over 1/3rd of a cross-section and is uniform over remaining 2/3rd of the cross- section, then the correction factor for kinetic energy is
The depth of flow for maximum velocity in a circular channel section with diameter equal to 1.5 m is
The critical depth of flow in a most economical triangular channel section for a discharge of 1 m3/sec is given by
Gradually varied flow in open channel is caused when
If the flow is subcritical, then after the introduction of hump the specific energy will decrease by ΔZ (height of hump).