Hydraulic jump occurs when flow changes from:

Concept:

Hydraulic jump: 

Whenever supercritical flow merges into subcritical flow then to reduce the energy a jump is formed, called a hydraulic jump.

For a rectangular frictionless channel, both depths are related as:

\(\frac{{{{\rm{y}}_2}}}{{{{\rm{y}}_1}}} = \frac{1}{2}\left[ {\sqrt {1 + 8{{\rm{F}}_1}^2} - 1} \right]\)

Froude number (F) = \(\sqrt {\frac{{{{\rm{Q}}^2}{\rm{T}}}}{{{\rm{g}}{{\rm{A}}^3}}}}\)

Where,

Y1 = Pre jump depth, Y2 = Post jump depth, F1 = Froude Number before jump, Q = Discharge, T = top width, and A = area of flow

Additional Information 

Based on the severity of jump and Froude number hydraulic jump is classified as follows:

Undular Jump:

• Froude number for this flow is between 1 to 1.7. Such type of jump is weak in nature and no significant water level rise is observed.

Weak Jump: 

• Froude number for this flow is between 1.7 to 2.5. These jumps are also natural jump and energy loss in these jumps are also less.

Oscillating Jump: 

• Froude number for this flow is between 2.5 to 4.5. It is oscillating in nature.

Steady Jump: 

• Froude number for this flow is between 4.5 to 9.

Strong Jump: 

• Froude number for this flow is greater than 9.0. Such a jump is generally engineered for heavy losses.