| | Flow conditions:
Fr < 1 | | Sub critical flow | Fr = 1 | | Critical flow | Fr > 1 | | Super critical flow |
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| | Q | | Flow discharge [m³/s] | A | | Wet area [m²] | P | | Wet perimeter [m] | T | | Surface width [m] | V | | Flow velocity [m/s] | R | | Hydraulic radius [m] | D | | Hydraulic depth [m] | Fr | | Froude number [-] | g | | Gravitational acceleration [9.81 m²/s] |
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Energy equation (Bernoulli) |
| | E | | Total energy [m] | ΔH | | Energy loss [m] | H | | Water level [m] | h | | Water height [m] | Z | | Bottom level [m] | L | | Flow line length [m] | V | | Flow velocity [m/s] | g | | Gravitational acceleration [9.81 m²/s] | S | | Slope [-] |
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| | ΔH | | Total loss [m] | ΔHF | | Friction loss [m] | ΔHM | | Minor losses [m] | L | | Flow line length [m] | J | | Unit friction loss [m/m] | K | | Local loss coefficient [-] | V | | Flow velocity [m/s] | g | | Gravitational acceleration [9.81 m²/s] |
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Friction loss / Kutter formula |
| | J | | Unit friction loss [m/m] | A | | Wet area [m²] | R | | Hydraulic radius [m] | S | | Slope [-] | b | | Friction coefficient [-] | ------------------------------
Concrete pipe | | b=0.35 | Plastic pipe | | b=0.10 |
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Friction loss / Manning formula |
| | J | | Unit friction loss [m/m] | A | | Wet area [m2] | R | | Hydraulic radius [m] | S | | Slope [-] | n | | Friction coefficient [-] | ------------------------------
Concrete pipe | | n=0.013 | Plastic pipe | | n=0.008 |
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