__Hydraulics Engineering Multiple Choice Questions (MCQ) for GATE | Fluid Mechanics | Part 1 | By Akhand Dutta__

## In a wide rectangular channel if the normal depth is increased by 20 %, then what is the approximate increase in discharge?

- A. 25%
- B. 30%
- C. 35%
- D. 40%

35%

## The maximum velocity in a channel section often occurs on the water surface.

- A. Above
- B. Below
- C. Between
- D. Top

Below

## What is the Froude’s number for a channel havingmean velocity 4.34 m/s and mean hydraulic depth of 3m?

- a) 0.4m
- b) 0.6m
- c) 0.7m
- d) 0.8m

0.8 m

## In a rectangular channel, the ratio of specific energy at critical depth EC to critical depth YC is

- a) 2
- b) 1
- c) 1.5
- d) 1.25

Write the correct answer here

## If the value of the rate of change of specific energy is 7.79×10-4 m and Sf = 0.00013, calculate the value of bed slope.

- a) 1 in 1000
- b) 1 in 1100
- c) 1 in 1200
- d) 1 in 1300

1 in 1100

## The velocity of flow through a channel is 0.74 m/s and the hydraulic radius of the channel is 1.11m, calculate the value of C if the bed slope of the channel is 1 in 5000.

- a) 40
- b) 45
- c) 50
- d) 55

50

## A trapezoidal channel with a base of 6 m and side slope of 2 horizontal to 1vertical conveys water at 17 m3/s with a depth of 1.5 m. is the flow situation is

- a) Subcritical
- b) supercritical
- c) both
- d) None of these

Subcritical

## The flow characteristics of a channel do not change with time at any point. What type of flow is it?

- a) Steady flow
- b) Uniform flow
- c) Laminar flow
- d) Turbulent flow

Steady Flow

## Water surface profiles that are asymptotic at one end and terminated at the other end would include

- a) H2 and S2
- b) H3 and S2
- c) M2 and H2
- d) M2 and H3

M2 and H2

## Calculate the velocity of flow in a triangular channel having depth 7m and the side slope of the channel is 1H:4V if the bed slope of the channel is 1 in 1200 and the slope of the energy line is 0.00010.Given: dy/dx=7.55m.

- a) 1 m/s
- b) 2 m/s
- c) 3 m/s
- d) 4 m/s

1 m/s

## M3 profile is indicated by which of the following conditions?

- a) Yo > Yc > Y
- b) Y > Yo > YC
- c) Y > YC > Y0
- d) YC > Y0 > Y

Yo > Yc > Y

## Measures velocity at a point of the fluid in a stream is

- a) Venturi meter
- b) pH meter
- c) Pitot-Static tubes
- d) None of the mentioned

Pitot-Static tubes

## A trapezoidal canal with side slopes 2: 1 has a bottom width of 4 m and carries a flow of 23 m3/s.the critical depth is

- a) 1.5
- b) 1.23
- c) 2.35
- d) 1.90

1.23

## A hydraulically efficient trapezoidal section of open channel flow carries water at the optimal depth of 0.6 m. Chezy coefficient is 75 and bed slope is 1 in 250. What is the discharge through the channel

- a) 1.44 m3/ s
- b) 1.62 m3/ s
- c) 15 m3/ s
- d) 2.24 m3/ s

1.62 m3/ s

## The Froude’s number for a flow in a channelsection is 1. What type of flow is it?

- a) Sub Critical
- b) Critical
- c) Super critical
- d) Tranquil

Critical

## In open channels, maximum velocity occurs:

- (a) near the channel bottom
- (b) in the mid-depth of flow
- (c) just below the free surface
- (d) at the surface

just below the free surface

## Calculate the aspect ratio having channel widthof 6m and depth of 8m.

- a) 0.75m
- b) 1.33m
- c) 1.50m
- d) 1.68m

0.75m

## For a channel to be economic which of thefollowing parameters should be minimum

- a) Wetted perimeter
- b) Wetted area
- c) Section factor
- d) Hydraulic depth

Wetted perimeter

## Calculate the discharge through a channel havinga bed slope 1 in 1000, area 12m2, hydraulic radius of 1.2m and Chezy’s constantbeing equal to 50.

- a) 17.98 m3/s
- b) 18.98 m3/s
- c) 19.98 m3/s
- d) 20.98 m3/s

20.98 m3/s

## The term alternate depth in an open channel flow refers to the

- a) Depths having the same specific energy for a given discharge
- b) Depths before and after the passage of the surge
- c) Depths having the same kinetic energy for a given discharge
- d) Depths on either side of hydraulic jump.

Depths having the same specific energy for a given discharge

## A hydraulically efficient rectangular channel of bed width 5m the hydraulic radius is equal to

- a) 2.5 m
- b) 5 m
- c) 1.25 m
- d) 2 m

1.25 m

## Which is the cheapest device for measuring flow/ discharge rate.

- a) Venturimeter
- b) Pitot tube
- c) Orificemeter
- d) None of the mentioned

Pitot tube

## For subcritical flow, the Froude number is

- a) Not equal to one
- b) Less than one
- c) Greater than one
- d) Equal to one

Less than one

## Calculate the value of Sf for a trapezoidal channel having depth 2m, width 5m, and side slope of 1H:1.5V. Given: dy/dx=1.18×10-3,S0 = 1 in 1000, C = 50

- a) 0.00001
- b) 0.00002
- c) 0.00003
- d) 0.00004

0.00001

## A hump is to be provided on the channel bed. The maximum height of the hump without affecting the upstream flow condition is

- a) 0.64 m
- b) 0.54 m
- c) 0.44 m
- d) 0.34 m

0.54 m

## A channel bed slope 0.0009 carries a discharge of 30 m3/ when the depth of flow is 1 .0 m What is the discharge carries by an exactly similar channel at the same depth of flow if the slope is decreased to 0.0001?

- a) 10 m3/ s
- b) 90 m3/ s
- c) 15 m3/ s
- d) 60 m3/ s

10 m3/ s

## Calculate the Froude’s number for a channel having discharge of 261.03m3/s, cross-sectional area of 42m2 and the top width being 6m

- a) 0.65
- b) 0.72
- c) 0.38
- d) 0.75

0.75

## Estimate the section factor for a channel section having cross-sectional area of 40m2 and hydraulic depth of 6 m.

- a) 94.3
- b) 95.6
- c) 97.9
- d) 100

97.9

## The direct step method of computation for GVF is

- a) applicable to non- prismatic channel
- b) applicable to prismatic channel
- c) both
- d) None of these

applicable to non- prismatic channel

## For a hydraulically efficient rectangular section the ratio of width tonormal depth is

- a) 0.5
- b) 1.0
- c) 2.0
- d) 3.5

2.0