Question

In open channel flow, the specific energy is the total energy per unit weight of a liquid, where the component potential energy is measured from the bed of the channel as the datum.

Hint:

In open channel flow, the specific energy is the sum of the flow depth and the velocity head. Ensure you have the correct values for flow rate and area.

Answer 1

Correct Answer: 1.1

The specific energy in open channel flow is given by: \[ E = h + \frac{V^2}{2g}, \] where:
- \( h \) is the depth of flow,
- \( V \) is the velocity of the flow,
- \( g \) is the acceleration due to gravity.
Given:
- \( h = 1 \, \text{m} \),
- \( V = \frac{Q}{A} = \frac{20}{10 \times 1} = 2 \, \text{m/s} \),
- \( g = 10 \, \text{m/s}^2 \).
The specific energy is: \[ E = 1 + \frac{2^2}{2 \times 10} = 1 + 0.2 = 1.2 \, \text{m}. \] Thus, the specific energy for this flow condition is \( 1.2 \, \text{m} \).