Hydraulic Jump Calculator
Estimate conjugate depth, upstream Froude number, and specific energy loss for a rectangular channel jump.
How to Use This Calculator
Measure upstream conditions
Enter depth y₁ and velocity v₁ at the supercritical approach section.
Compute Fr₁ and y₂
The calculator gives Froude number, conjugate depth, and energy loss.
Interpret results
Large Fr₁ implies stronger jumps and greater energy dissipation.
Formula
y₂/y₁ = 0.5 · ( -1 + √(1 + 8·Fr₁²) )
Fr₁ = v₁ / √(g y₁)
Where: y₁ = upstream depth, y₂ = sequent (downstream) depth, v₁ = approach velocity, g = 9.80665 m/s².
Example: y₁ = 0.3 m, v₁ = 4 m/s → Fr₁ ≈ 2.31 → y₂/y₁ ≈ 2.61 → y₂ ≈ 0.783 m.
About Hydraulic Jumps
Hydraulic jumps occur when supercritical flow transitions to subcritical flow, dissipating energy through turbulence and roller formation.
- Used in stilling basins for energy dissipation.
- Strength and air entrainment increase with Fr₁.
Frequently Asked Questions
Channel shape?
This model assumes a horizontal, rectangular channel with hydrostatic pressure distribution.
Bed slope effects?
Mild slopes are acceptable; strong slopes require more advanced analysis.