- Asked 2/23
- 2079 Chaitra · 2 marks
- 2076 Bhadra · 1 mark
Pipe flow versus open channel flow
Short answer
Pipe flow runs full in a closed conduit, driven by pressure difference, with fixed area and may flow uphill. Open channel flow has a free surface at atmospheric pressure, driven by gravity, with variable area and depth, and flows only downhill.
Differentiate between pipe flow and open channel flow.
Pipe flow takes place in a closed conduit running full, driven by pressure difference. Open channel flow has a free surface exposed to atmosphere, driven by gravity.
| Basis | Pipe flow | Open channel flow |
|---|---|---|
| Section | Closed conduit, flows full | Free surface exposed to atmosphere |
| Driving force | Pressure gradient (and gravity) | Gravity (slope of bed) |
| Pressure at surface | Above or below atmospheric | Atmospheric (zero gauge) |
| Hydraulic grade line | Piezometric head, may rise above pipe | Coincides with water surface |
| Flow area | Fixed by pipe size | Changes with depth, so is a variable |
| Cross-section | Almost always circular | Any shape (rectangular, trapezoidal, circular, natural) |
| Roughness | Fairly constant, well known | Varies, difficult to estimate (e.g., river beds) |
| Analysis | Simple, more accurate | More complex, empirical |
| Flow direction | Can go uphill | Only downhill (by gravity) |
| Examples | Water supply main, penstock | River, canal, partially full sewer, culvert |
A pipe flowing partly full behaves as open channel flow.
✓ Answer checked by Claude Opus 5.5 (high effort)
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