Saut hydraulique

A hydraulic jump is a sudden rise in fluid depth that occurs when high-velocity water transitions to a slower flow. 

This only happens in supercritical flow, where the Froude number exceeds 1. In subcritical flow (a Froude number less than 1), hydraulic jumps cannot form because the flow lacks the excess energy needed for the transition.

Hydraulic jumps are classified by their upstream Froude number, each with distinct features. These types include Jump Impossible, Standing Wave or Undulant Jumps, Weak Jumps, Oscillating Jumps, Stable Jumps, and Strong Jumps. 

The depth ratio across the jump and energy dissipation, or head loss, depend on the upstream Froude number. As the Froude number increases, the depth ratio also rises, signifying a more significant change in depth through the jump.

In engineering, hydraulic jumps are essential for dissipating energy in structures like dam spillways. 

High-speed water from a spillway can erode downstream channels, but a hydraulic jump helps slow the water, converting it to subcritical flow and protecting these areas.

Hydraulic jumps can also appear in various configurations, such as submerged jumps, depending on channel slope or obstacles.