Question

Surge wave in a rectangular channel is an example of
A. Steady flow
B. Unsteady flow
C. Uniform flow
D. Non-uniform flow
(This question has multiple correct options)

Answer 1

Surges are defined as a moving wave front which results in the change of depth of flow. Steady flow is defined as the flow in which all the conditions like velocity, pressure, etc at any point remain constant. While, unsteady flow is a flow in which the conditions can change at any point with respect to time. Flow is called a uniform flow if the velocity of flow does not change with length. If the velocity of flow changes with length is called non-uniform flow.

Complete step by step answer:
The sudden change of flow in the channel which causes increase or rise in the water level is known as surge. This change of flow is due to low pressure and high winds. As the pressure does not remain constant, it is an example of unsteady flow.
From Bernoulli's principle we know, as the pressure changes, velocity also changes. So, as the pressure on the water changes, the velocity with which the water was flowing also changes. So, from the definition of the uniform flow, a surge wave is an example of non-uniform motion.
Hence, surge waves in a rectangular channel is an example of unsteady and non-uniform flow.
So, the correct answers are option B and D i.e. unsteady flow and uniform flow respectively.

Note:
To answer these types of questions, you should know the difference between steady and unsteady flow and uniform and non-uniform flow. You should also know examples of these types of flows. So that if you don't know the given example is which type of flow, you can refer to other examples or definitions of flows. The flow of water in a pipe of constant diameter at constant velocity is an example of steady uniform flow.