# Open Channel Flow MCQs with Answers

### Fluid Mechanics & Hydraulics (3140611)

#### MODULE 6: OPEN CHANNEL FLOW

1. A structure whose width is __________ the width of the channel, is called a flumed structure.
A. less than
B. more than
Answer: Option A

2. In open channels, the specific energy is the
A. total energy per unit discharge
B. total energy measured with respect to the datum passing through the bottom of the channel
C. total energy measured above the horizontal datum
D. kinetic energy plotted above the free surface of water
Answer: Option B

3. Whenever a plate is held immersed at some angle with the direction of flow of the liquid, it is subjected to some pressure. The component of this pressure, at right angles to the direction of flow of the liquid is known as lift.
A. True
B. False
Answer: Option A

4. The depth of water in a channel corresponding to the minimum specific energy is known as critical depth.
A. Agree
B. Disagree
Answer: Option A

5. The depth of water in a channel corresponding to the minimum specific energy is known as critical depth.
A. Agree

B. Disagree
Answer: Option A

6. If the depth of water in an open channel is greater than the critical depth, the flow is called
A. critical flow
B. turbulent flow
C. tranquil flow
D. torrential flow
Answer: Option C

7. The flow in a pipe or channel is said to be non-uniform when
A. the liquid particles at all sections have the same velocities
B. the liquid particles at different sections have different velocities
C. the quantity of liquid flowing per second is constant
D. each liquid particle has a definite path
Answer: Option B

8. The flow characteristics of a channel does 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
Answer: a

9. The Reynolds number for a flow in a channel is 1000. What type of flow is it?
a) Laminar
b) Turbulent
c) Transition

d) Steady
Answer: c

10. Calculate the aspect ratio having channel width of 6m and depth of 8m.
a) 0.75m
b) 1.33m
c) 1.50m
d) 1.68m
View Answer
Answer: b
Explanation: Aspect ratio = Depth / width = 8/6 = 1.33m.

11. Calculate the mean hydraulic depth of a channel having top width of 7m and cross sectional area of
35m2.
a) 4m
b) 5m
c) 6m
d) 7m
Answer: b
Explanation: Hydraulic depth (D) = A/T = 35/7 = 5m.

12. The discharge in an open channel corresponding to critical depth is
(A) Zero
(B) Minimum
(C) Maximum
(D) None of these
Answer: Option C

13. The velocity at which the flow changes from laminar flow to turbulent flow is called

A. critical velocity
B. velocity of approach
C. sub-sonic velocity
D. super-sonic velocity
Answer: Option A