Open Channel Flow · Fluid Mechanics and Hydraulic Machines · GATE CE

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Marks 1

1

A hydraulic jump occurs in an open channel when the slope of the channel changes from__________ .

GATE CE 2025 Set 2
2
When a supercritical stream enters a mild-sloped (M) channel section, the type of flow profile would become _________.
GATE CE 2023 Set 1
3

G1 and G2 are the slopes of the approach and departure grades of a vertical curve, respectively.

Given |G1| < |G2| and |G1| ≠ |G2| ≠ 0

Statement 1 : +G1 followed by +G2 results in a sag vertical curve.

Statement 2 : −G1 followed by −G2 results in a sag vertical curve.

Statement 3 : +G1 followed by −G2 results in a crest vertical curve.

Which option amongst the following is true?

GATE CE 2023 Set 1
4

A hydraulic jump takes place in a 6 in wide rectangular channel at a point where the upstream depth is 0.5 m (just before the jump). If the discharge in the channel is 30 m3/s and the energy loss in the jump is 1.6 m, then the Froude number computed at the end of the jump is _________. (round off to two decimal places)

(Consider the acceleration due to gravity as 10 m/s2.)

GATE CE 2022 Set 2
5

Water is flowing in a horizontal, frictionless, rectangular channel. A smooth hump is built on the channel floor at a section and its height is gradually increased to reach choked condition in the channel. The depth of water at this section is y2 and that at its upstream section is y1. The correct statements for the chocked and un-chocked conditions in the channel is/are

GATE CE 2022 Set 2
6

A rectangular channel with Gradually Varied Flow (GVF) has a changing bed slope. If the change is from a steeper slope to a steep slope, the resulting GVF profile is

GATE CE 2022 Set 1
7

Depth of water flowing in a 3 m wide rectangular channel is 2 m. The channel carries a discharge of 12 m3/s. Take g = 9.8 m/s2. The bed width (in m) at contraction, which just causes the critical flow, is _________ without changing the upstream water level. (round off to two decimal places)

GATE CE 2022 Set 1

Marks 2

1

Consider flow in a long and very wide rectangular open channel. Width of the channel can be considered as infinity compared to the depth of flow. Uniform flow depth is 1.0 m . The bed slope of the channel is 0.0001 . The Manning roughness coefficient value is 0.02 . Acceleration due to gravity, g can be taken as $9.81 \mathrm{~m} / \mathrm{s}^2$.

The critical depth (in m ) corresponding to the flow rate resulting from the above conditions is ________ (round off to one decimal place).

GATE CE 2025 Set 2
2

Lacey's regime equations, followed in India for making scour calculations while designing hydraulic structures across alluvial channels, are given below. Regarding these equations, which of the following statements is/are true:

$$ \begin{aligned} & D=0.470 \times\left[\frac{Q}{f_s}\right]^{1 / 3} \\ & P=4.75 \times \sqrt{Q} \\ & f_s=1.76 \times \sqrt{d} \end{aligned} $$

where, $Q$ is discharge and $f_s$ is silt factor

GATE CE 2025 Set 1
3

A hydraulic jump is formed in a 5 m wide rectangular channel, which has a horizontal bed and is carrying a discharge of $15 \mathrm{~m}^3 / \mathrm{s}$. The depth of water upstream of the jump is 0.5 m . The power dissipated by the jump (in kW ) is ________ (rounded off to the nearest integer).

Note:

Acceleration due to gravity $=9.81 \mathrm{~m} / \mathrm{s}^2$

Density of water $=1000 \mathrm{~kg} / \mathrm{m}^3$

Kinetic energy correction factor $=1.0$

GATE CE 2025 Set 1
4

A 5.0 m wide rectangular channel carries a discharge of $10 \mathrm{~m}^3 / \mathrm{s}$ at a depth of 1.5 m under uniform flow. To produce critical flow conditions without affecting the upstream conditions, the channel bottom elevation should be raised (in m ) by _________ (rounded off to 2 decimal places).

Assume that there is no loss of head at the raise, kinetic energy correction factor is 1.0 , and acceleration due to gravity is $9.81 \mathrm{~m} / \mathrm{s}^2$.

GATE CE 2025 Set 1
5

A compound symmetrical open channel section as shown in the figure has a maximum of _______ critical depth(s).

GATE CE 2023 Set 2 Fluid Mechanics and Hydraulic Machines - Open Channel Flow Question 8 English

Bm – Bottom width of main channel

Bf – Bottom width of flood channel

ym – Depth of main channel

y – Total depth of the channel

nm – Manning’s roughness of the main channel

nf – Manning’s roughness of the flood channel

GATE CE 2023 Set 2
6

The critical flow condition in a channel is given by _______.

[Note: 𝛼 – kinetic energy correction factor; 𝑄 – discharge; Ac – cross-sectional area of flow at critical flow condition; Tc – top width of flow at critical flow condition; 𝑔 – acceleration due to gravity]

GATE CE 2023 Set 2
7

The cross-section of a small river is sub-divided into seven segments of width 1.5 m each. The average depth, and velocity at different depths were measured during a field campaign at the middle of each segment width. The discharge computed by the velocity area method for the given data is _____ m3/s (round off to one decimal place).

Segment Average depth (D) (m) Velocity (m/s) at 0.2D Velocity (m/s) at 0.6D Velocity (m/s) at 0.8D
1 0.40 -- 0.40 --
2 0.70 0.76 -- 0.70
3 1.20 1.19 -- 1.13
4 1.40 1.25 -- 1.10
5 1.10 1.13 -- 1.09
6 0.80 0.69 -- 0.65
7 0.45 -- 0.42 --
GATE CE 2023 Set 2
8

A very wide rectangular channel carries a discharge (Q) of 70 m3/s per meter width. Its bed slope changes from 0.0001 to 0.0009 at a point P, as shown in the figure (not to scale). The Manning’s roughness coefficient of the channel is 0.01. What water surface profile(s) exist(s) near the point P?

GATE CE 2023 Set 1 Fluid Mechanics and Hydraulic Machines - Open Channel Flow Question 10 English
GATE CE 2023 Set 1
9
A hydraulic jump occurs in a 1.0 m wide horizontal, frictionless, rectangular channel, with a pre-jump depth of 0.2 m and a post-jump depth of 1.0 m. The value of g may be taken as 10 m/s2. The values of the specific force at the pre-jump and post-jump sections are same and are equal to (in m3, rounded off to two decimal places) _____________ .
GATE CE 2023 Set 1
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