Hydraulic Jumps Explained

Fig. 1: A Standing Wave (aka Stationary hydraulic jump) occurs when a flow of liquid at high velocity discharges into a zone of the river or engineered structure which can only sustain a lower velocity
A hydraulic jump is a phenomenon common in open channel flow. If flow before the jump is supercritical, a jump will occur and flow after the jump will be subcritical. The jump destroys excess energy (velocity).
In lamens terms, a hydraulic jump occurs when fast moving liquid (in the supercritical state) contacts slow moving liquid, which converts some of the flows kinetic energy (i.e. speed) into potential energy (i.e. height).
Hydraulic Jump Equations:
Depths
where
- y2 = depth after the jump (ft)
- y1 = depth before the jump (ft)
- V1 = velocity before the jump (fps)
- y2 & y1 = are called conjugate depths
Head Loss
where
- hL = head loss in the jump (ft)
Energy Loss
where
- HP = energy dissipated by the jump (hp)