Introduction

• The hydraulic jump is defined as the rise of water level, which takes place due to transformation of the unstable shooting flow to the stable streaming flow.
• The hydraulic jump converts kinetic energy of rapidly flowing into potential energy.
• Due to this there is a loss of kinetic energy.
• When hydraulic jump occurs, a loss of energy due to eddy formation and turbulence flow occurs.
• In an Open channel when rapidly flowing stream abruptly changes to slowly flowing stream, a distinct rise or jump in the elevation of liquid surface takes, this phenomenon is known as hydraulic jump.
• The hydraulic jump is also known as a standing wave because it is, in essence, a wave which is stationary at one place.

Assumptions

• Loss of head due to friction is negligible.
• The flow is uniform and the pressure distribution is hydrostatic before and after the jump.
• Channel is horizontal hence the weight component in the direction is neglected.
• The flow is steady.
• The momentum correction factor is unity.

Location of Hydraulic Jump

• Below control structures like weir, sluice are used in the channel.
• When any obstruction is found in the channel.
• When a sharp change in the channel slope takes place.
• At the toe of a spillway dam.

Effects of Hydraulic Jump

• Actually the hydraulic jump usually acts as the energy dissipater. It clears the surplus energy of water.
• Usually when the hydraulic jump takes place, the considerable amount of air is trapped in the water. That air can be helpful in removing the wastes in the streams that are causing pollution.
• Due to the hydraulic jump, may noticeable disturbances are created in the following water like eddies, reserve flow.

Applications

• Usually hydraulic jump reserves the flow of water. This phenomenon can be used to mix chemicals for water purification.
• Hydraulic jump can be used to remove the air from water supply and sewage line to prevent the air locking.
• Hydraulic jump usually maintains the high water level on the downstream side. The water level can be used for irrigation purposes.
• Hydraulic jump issued to dissipate or destroy the energy of water where it is not needed otherwise it may cause damage to hydraulic structures.
• It may also be used as a discharge measuring device.
• It may be used for mixing of certain chemicals like in case of water treatment plants.
• Aeration of stream polluted by biodegradable waste.
• Raising the water level in the channel for irrigation.
• Efficient operation of flow measurement flumes.