Specific Energy in Open Channel Flow
Specific Energy in Open Channel Flow
Specific energy — depth plus velocity head — governs open-channel behaviour and where critical flow and hydraulic jumps occur.
The specific energy is E = y + v²/(2g). where y is the flow depth, v the velocity and g gravity.
Inputs
y := 1.5 m=1.5 m
v := 3 m/s=3 m/s
g := 9.81 m/s^2=9.81 m/s^2
Add depth to velocity head.
E := y + v^2/(2·g)=1.96 m
Results
For a given flow there is a minimum specific energy at critical depth; the same energy can occur at a deep slow flow or a shallow fast one.
Assumptions & limitations
- Measured from the channel bed.
- Nearly uniform velocity.
- Small channel slope.