# What is Hydraulic jump: Definition and 11 Discussions

A hydraulic jump is a phenomenon in the science of hydraulics which is frequently observed in open channel flow such as rivers and spillways. When liquid at high velocity discharges into a zone of lower velocity, a rather abrupt rise occurs in the liquid surface. The rapidly flowing liquid is abruptly slowed and increases in height, converting some of the flow's initial kinetic energy into an increase in potential energy, with some energy irreversibly lost through turbulence to heat. In an open channel flow, this manifests as the fast flow rapidly slowing and piling up on top of itself similar to how a shockwave forms.
It was first observed and documented by Leonardo da Vinci in the 1500s. The mathematics were first described by Giorgio Bidone when he published a paper in 1820 called Experiences sur le remou et sur la propagation des ondes.The phenomenon is dependent upon the initial fluid speed. If the initial speed of the fluid is below the critical speed, then no jump is possible. For initial flow speeds which are not significantly above the critical speed, the transition appears as an undulating wave. As the initial flow speed increases further, the transition becomes more abrupt, until at high enough speeds, the transition front will break and curl back upon itself. When this happens, the jump can be accompanied by violent turbulence, eddying, air entrainment, and surface undulations, or waves.
There are two main manifestations of hydraulic jumps and historically different terminology has been used for each. However, the mechanisms behind them are similar because they are simply variations of each other seen from different frames of reference, and so the physics and analysis techniques can be used for both types.
The different manifestations are:

The stationary hydraulic jump – rapidly flowing water transitions in a stationary jump to slowly moving water as shown in Figures 1 and 2.
The tidal bore – a wall or undulating wave of water moves upstream against water flowing downstream as shown in Figures 3 and 4. If one considers a frame of reference which moves along with the wave front, then the wave front is stationary relative to the frame and has the same essential behavior as the stationary jump.A related case is a cascade – a wall or undulating wave of water moves downstream overtaking a shallower downstream flow of water as shown in Figure 5. If considered from a frame of reference which moves with the wave front, this is amenable to the same analysis as a stationary jump.

These phenomena are addressed in an extensive literature from a number of technical viewpoints.Hydraulic Jump is used sometimes in mixing chemicals.

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1. ### Fluids and a hydraulic jump

I have 90% of this done. When i looked in my manual i noticed an odd jump they made and i don't get why. that is where i need the help V1(b1h1) = V1(b2h2) Im solving for h2. What i can't figure out is what to use for the base measurement of the cross section of the water. i have no idea how...
2. ### A Hydraulic jumps: Why do they occur when/where they do?

Hi guys, I've been doing some light reading on hydraulic jumps. For example: So I've been through the basics, super critical to sub ciritcal etc: https://en.wikipedia.org/wiki/Hydraulic_jump So far I understand that the jump occurs at the two points either side of the critical depth, like we...
3. ### Question about hydraulic jump assumptions

Sorry for the poor image... A better picture can be viewed here https://www.dropbox.com/s/uyi01l27vu2fwyw/96.png?dl=0 I don't understand the assumption in the red box... If I don't ignore the atmospheric pressure, F_1 = integrate from 0 to h_1 (ρg(h_1-z)+p_a)dz = 1/2 ρgh_1^2 + p_a*h_1, similarly...
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### Volume Flux for a Hydraulic Jump

Homework Statement Problem is given in this image, https://gyazo.com/454370ff9549dcd7c53604ebfe5df105 Homework Equations Continuity or conservation of mass equation: \frac{\partial u}{\partial x} + \frac{\partial w}{\partial z} = 0 Where u is the horizontal velocity and w is the vertical...
5. ### Understanding Hydraulic Jump: Basics & Calcs

Homework Statement http://www.brighthubengineering.com/hydraulics-civil-engineering/55054-open-channel-flow-basics-hydraulic-jump-calculations/ In th earlier part of this notes , i was told that the The hydraulic jump is an abrupt transition to subcritical from supercritical flow. but , in...
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### How to Solve Hydraulic Jump Problems with Conservation of Momentum and Mass?

Homework Statement The question is stated here, though I'm happy to repost but they include a picture. I should say this is not homework, I'm doing problems for practice. http://web.mit.edu/2.25/www/5_pdf/5_04.pdf Homework Equations Conservation of momentum/mass The Attempt at a Solution...
7. ### Horizontal open channel flow -- Hydraulic jump calculation

Dear Fellow Engineers I'm having an issues with my calculations. This case concerns a open channel flow that start off being supercritical on the left and turns into subcritical flow after a hydraulic jump. Given: Volume flow rate Q = 0.16m^3/s Width of the channel b = 1m Resulting...
8. ### Impact force on a falling object that spreads

Hi, Homework Statement I'm doing some research into the hydraulic jump and was wanting some help in calculating the impact force. Hydraulic jump is a phenomenon to do with the turbulence of the water - it is the 'ring' around the stream of water when a tap is turned on Homework Equations The...
9. ### Impact Force of a falling object causing it to spread out

Hi, I'm doing some research into the hydraulic jump and was wanting some help in calculating the impact force. The equation I have found to use is: F = m g h / s I have the mgh, and was wondering what to use as the slow down distance. If you didn't know what the hydraulic jump was, it is a...
10. ### Shear Forces Explained: Hydraulic Jump

Please, say me what are shear forces. I've been looking for it because I was studying a phenomenon called hydraulic jump. In this example, are these forces caused by the cohesion forces?
11. ### Project: Hydraulic Jump or Ball Spin

These are the problems I have to choose between for a school project entering a competition. There are other problems but these are the ones I'm torn between. Hydraulic jump When a smooth column of water hits a horizontal plane, it flows out radially. At some radius, its height suddenly...