Sudden transition from supercritical (Fr > 1) to subcritical flow in a rectangular channel. Computes sequent depth y2, downstream Fr2, energy loss ΔE, and classifies the jump type.
Open Channel Flow · HydraulicsSpecify upstream conditions by:
Must give Fr1 = V1/√(gy1) > 1 for a valid jump
Belanger equation (rectangular channel):
Jump type classification (Peterka):
| Fr1 | Jump type | Energy loss |
|---|---|---|
| 1.0–1.7 | Undular | ~0%Surface ripples, poor dissipation |
| 1.7–2.5 | Weak | 5–15%Smooth, low dissipation |
| 2.5–4.5 | Oscillating | 15–45%Unsteady — avoid in design |
| 4.5–9.0 | Steady | 45–70%Best for stilling basins |
| > 9.0 | Strong | > 70%Very rough, churn |
Tailwater control:
A hydraulic jump forms at the location where the sequent depth y2 equals the actual tailwater depth. If tailwater < y2, the jump sweeps downstream (swept-out jump). If tailwater > y2, the jump is submerged and energy dissipation is reduced.