- 2080 Chaitra · 3 marks
Classification of hydraulic jump by Froude number
Short answer
Based on upstream Froude number Fr₁: undular (1.0–1.7), weak (1.7–2.5), oscillating (2.5–4.5), steady (4.5–9.0), and strong (>9). Steady jump dissipates 45–70% energy and is preferred for stilling basins.
Classify the hydraulic jump based on Froude number.
Hydraulic jumps are classified by the upstream Froude number (USBR classification):
| Type of jump | Features | |
|---|---|---|
| 1.0 | No jump | critical flow |
| 1.0 to 1.7 | Undular jump | surface shows undulations (standing waves); little energy loss (under 5%) |
| 1.7 to 2.5 | Weak jump | series of small rollers; smooth downstream surface; loss 5 to 15% |
| 2.5 to 4.5 | Oscillating jump | jet oscillates between bed and surface, producing irregular waves that travel far downstream; loss 15 to 45% |
| 4.5 to 9.0 | Steady jump | well-balanced, stable and well-defined; best for energy dissipation; loss 45 to 70% |
| above 9.0 | Strong jump | rough, choppy surface, high energy dissipation (over 70%), but the downstream waves can be damaging |
The percentage of energy lost, , rises with . Stilling basins are designed to produce a steady jump ( to ); oscillating jumps are avoided.
✓ Answer checked by Claude Opus 5.5 (high effort)
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