Open Channel Flow
Open channel flow is the flow of fluid (typically water) in a channel with a free surface. The Manning equation (V = (1/n) × R^(2/3) × S^(1/2)) is commonly used for uniform flow. The Chezy equation (V = C × √(R × S)) is another empirical formula. Critical flow occurs when the Froude number (Fr) equals 1. Subcritical flow (Fr < 1) is tranquil, while supercritical flow (Fr > 1) is rapid. The hydraulic jump is a transition from supercritical to subcritical flow.
Knowledge Check
1.A rectangular channel has width 2 m, depth 1.5 m, and velocity 2 m/s. What is the flow rate?
2.In the Manning equation, what does 'n' represent?
3.A trapezoidal channel has a bottom width of 3 m, side slope of 1:1 (H:V), and flow depth of 2 m. What is the wetted perimeter (P)?
4.What is the Froude number for a flow with velocity 3 m/s, flow depth 1.2 m, and width 4 m? (g = 9.81 m/s²)
5.The specific energy in open channel flow is defined as:
6.A hydraulic jump occurs when flow changes from:
7.In a rectangular channel, the critical depth (y_c) is given by:
8.A channel with Manning's n = 0.025, hydraulic radius R = 2 m, and slope S = 0.001. What is the velocity?
9.The most efficient hydraulic section (minimum wetted perimeter) for a given area is:
10.A weir is used to measure flow in an open channel by: