Question

The phenomenon occurring in an open channel when a rapidly flowing stream abruptly changes to slowly flowing stream causing a distinct rise of liquid surface is

Answer 1

This is due to the Principle of Uniform Flow of water in hydrostatics..
mathematically,
A1V1 = A2V2
where, A = surface area, V= velocity
Now, as the velocity of water decreases the surface area should increases..

Answer 2

The phenomenon occurring in an open channel when a rapidly flowing stream abruptly changes to a slowly flowing stream causing a distinct rise of liquid surface is a hydraulic pump.

• Hydraulic jump is dependent on the speed of fluid because when it is reached at or above critical speed only then jump is possible.
• It is due to the change in speed of fluid when encountered by obstruction.
• In this phenomenon, turbulence occurs and energy is dissipated by fluid to maintain the speed of the wave.
• Hydraulic jumps are used in the dissipation of energy in outlets.
• It also functions by preventing air locking in sewage and water supply units.
• There are many types of hydraulic jumps such as undular hydraulic jump, weak hydraulic jump, steady hydraulic jumps, and an oscillating hydraulic jump.