The science of hydraulics is an interesting area of study as well as practical life. The hydraulic jump is one of the most common situations in hydraulic science. The hydraulic jump can be seen in open channel flow. Open channel flow indicates river or various spillways. This whole phenomenon was first observed and discussed by Leonardo da Vinci in the 1500s. But based on the discussion, the mathematical details of the hydraulic jump were discovered by Giorgio Bidone of Turin University.
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Hydraulic jump: What is it?
Maintaining the flow of water is an inseparable part of civil engineering which helps obtain modern infrastructure and flood management. Also, engineers need to predict how water behaves while planning irrigation. Fluid mechanics help to understand the behaviour of water.
A hydraulic jump is a jump or standing wave formed when the depth or flow of water changes. Usually, it changes from a supercritical to a subcritical state.
When the slope of the open channel lowers from steep to shallow, the depth of the water flow rises towards the critical depth, and at some point, the flow becomes unstable. The flow becomes turbulent until a new standard depth is adapted on the upstream side. This phenomenon is known as a hydraulic jump.
Hydraulic jump: Crucial terms related to the open channel flow
- Depth of flow: Depth at which water can flow above the ground level in an open channel.
- Critical depth: Minimum depth on the ground where the flow velocity is too high. Also, at this depth, the flow occurs with more turbulence. The velocity of water at this depth is called critical velocity.
- Supercritical depth: Supercritical depth is the depth of water less than the critical depth and describes the extremely severe supercritical conditions of the underlying flow that occur in dams or other irrigation structures.
- Subcritical depth: This is deeper than critical depth, but the velocity is lower than critical velocity.
Hydraulic jump: Features
Hydraulic jump has a few characteristics to consider, which are as follows:
- The hydraulic jump is always unstable.
- The hydraulic jump is irregular.
- If the wind direction changes, the property of the hydraulic jump can change quickly.
Hydraulic jump: Uses
A hydraulic jump is inevitably formed to lower the energy of the water as the drain pipe flows down the overflow. It is important to reduce that energy and maintain a steady speed. This phenomenon is termed energy dissipation in hydraulic structures.
Also, the hydraulic jump can easily remove air from the pipeline, which helps remove air locking.
Hydraulic jump: Types
Undular hydraulic jump
The undular jumps are irregular, poorly shaped, and have turbulence in the water particles.
Weak jump
A weak jump comes when water velocity is very low, and the water particles can not stay stable and flow differently.
Oscillating hydraulic jump
As the oscillating jet enters a supercritical state, an oscillating jump occurs where many particles oscillate clockwise or counterclockwise, creating small tides or waves on the upper surface. Flow also depends on strong unidirectional air currents.
Steady hydraulic jump
In stable jumps, the bed’s surface is so rough that the particles tend to travel in a single direction with a higher velocity and turbulence, which results in high frictional losses in this type of hydraulic jump.
Strong hydraulic jump
A strong jump is a complete jump that occurs when there is high friction loss, equal air pressure distribution, and very high speeds, resulting in losses. This jump is highly preferred in dam structures because water changes from supercritical to subcritical in a short span compared to all other hydraulic jumps.
FAQs
What is the main benefit of hydraulic jump?
Hydraulic jump helps to maintain a stable flow and velocity of the fluid.
What is the distance of a hydraulic jump?
The hydraulic jump length is roughly 5 to 7 times its height.
Which are the two main types of hydraulics?
Two main hydraulics are open-loop hydraulic systems and closed-loop hydraulic.
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