### 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

y_2 = -\frac{y_1}{2} + \sqrt{\left(\frac{y_1}{2}\right)^2 + \frac{2V_1^2y_1}{g}}

*where*

**y**= depth after the jump (ft)_{2}**y**= depth before the jump (ft)_{1}**V**= velocity before the jump (fps)_{1}**y**= are called conjugate depths_{2}& y_{1}

#### Head Loss

h_L = \frac{(y_2 - y_1)^3}{4y_1 y_2}

*where*

**h**= head loss in the jump (ft)_{L}

#### Energy Loss

HP = \frac{\gamma Q h_j}{550}

*where*

**HP**= energy dissipated by the jump (hp)