What is hydraulic jump in open channel flow?

A hydraulic jump is a phenomenon that occurs in fast moving open flows when the flow becomes unstable. When a jump occurs, the height of the liquid surface increases abruptly, resulting in an increased depth and decreased average flow velocity downstream.

What are the increases in open channel current?

A wave in an open channel is a sudden change in flow depth (ie, sudden increase or decrease in depth). An abrupt increase in flow depth is called a positive wave, while a sudden decrease in depth is called a negative wave. This image shows a wavy wave (Photo, propagation from left to right).

How does a hydraulic jump occur?

A hydraulic jump occurs when two fluids of the same fluid (especially water) in an open channel, which actually meet a subcritical flow of sufficient depth from a supercritical flow of high velocity, then there is an abrupt increase in the height of the downstream channel – this phenomenon with energy transfer is called…

Why is gravity important in open channel flow?

Open channel flow, also called free gravity flow, is the flow of water induced by the action of gravity. The surface of the flowing liquid is at atmospheric pressure and free of air. In open channel flow, the liquid has a free surface.

What is the difference between subcritical and supercritical flow?

Subcritical flow is dominated by gravitational forces and behaves in a slow or steady manner. It is defined as having a Froude number less than one. Supercritical flow is dominated by inertial forces and behaves as rapid or unsteady flow. Supercritical flow has a Froude number greater than one.

What is meant by critical flow?

critical flow The flow that occurs when the flow velocity in a river channel equals the wave velocity generated by a disturbance or obstruction. In this condition, the Froude number (Fr) = 1. When Fr is greater than 1, waves cannot be generated upstream and the flow is said to be supercritical, fast, or surging.

What is surge?

In general, a surge is a transient surge of current, voltage, or power in an electrical circuit. Surges or transients are brief surges or disturbances in a current waveform that can damage, degrade, or destroy electronic equipment in any home, commercial building, industry, or manufacturing facility.

What is the positive increment?

A positive surge is an unsteady, rapidly varied and highly turbulent open channel flow, characterized by a sudden rise in water surface elevation (Henderson, 1966, Liggett, 1994, Chanson, 2004). Industrial situations include rejection surges in hydropower and water supply channels (Favre, 1935, CUNGE, 1966).

Is hydraulic jump a flow control?

A hydraulic jump is a phenomenon in the science of hydraulics that is often observed in open channel flows such as rivers and weirs. In an open channel flow, this manifests as the rapid flow rapidly slowing down and piling up on top of itself, just as a shock wave is formed.

How do you know where a hydraulic jump will occur?

A hydraulic jump occurs when the upstream flow is supercritical (F>1). In order to have a jump, there must be a flow inhibition downstream. The downstream obstacle can be a spillway, a bridge structure, a dam or simply channel friction. The water depth increases during a hydraulic jump, and the energy is dispersed as turbulence.

What are the characteristics of open channel flow?

In contrast to pipe flows, open channel flows are characterized by a free surface exposed to the atmosphere. The pressure at this boundary thus remains roughly constant regardless of changes in water depth and flow velocity.

What is the difference between pipe flow and open channel flow?

Pipe Flow vs Open Channel Flow Open Channel Flow is a type of fluid flow in a conduit with a free surface open to the atmosphere. Pipe flow is a type of flow in a closed conduit. The maximum velocity occurs in the center of the tube.

What makes an open channel flow a stratified flow?

Such flows are free surface flows but not open channels (Figure 5-2), although they are usually called stratified flows because the density difference between the two fluids gives rise to gravitational effects in the flow. On the other hand, open channel flows by their definition are also free surface flows. Figure 5-1.

What happens when you decrease the slope of a channel?

On the other hand, if you reduced the channel slope to be very gentle, you would eventually have a condition where the flow was relatively deep at the upstream end and relatively shallow at the downstream end (Figure 5-6B). Somewhere between these two extreme conditions there would be a slope where the flow was nearly uniform.

Why are open channel flows called free surfaces?

1. INTRODUCTION 1Open channel flows are those not completely contained within rigid boundaries; part of the flow is in contract with anything but empty space (Figure 5-1). The surface of the flow thus formed is called a free surface because the flow boundary is freely deformable in contrast to the fixed boundaries.

What is the problem with a uniform open channel current?

A uniform open channel flow: the depth and velocity profile are the same in all sections along the flow. 12One kind of problem associated with uniform flow is what the channel slope will be if discharge Q, water depth d, and bottom sediment size are dry specified or imposed on the flow.