Open channel flow is the flow of fluid with a free surface, where the free surface is exposed to atmospheric pressure. It occurs due to the force of gravity down a sloped channel bed. Open channel flow can be steady or unsteady, uniform or non-uniform, laminar or turbulent, and subcritical, critical, or supercritical. Non-uniform flow is classified as either rapidly varied flow where depth changes abruptly, or gradually varied flow where changes occur gradually over a long length. Discharge in open channels can be calculated using Chezy's formula, which relates discharge, velocity, hydraulic radius, and channel roughness.

1. OPEN CHANNEL FLOW
Amos Gamaleal David

2. Open Channel Flow
• Flow of Fluid with Free Surface
• Free surface is a surface having constant pressure(atm
Pressure
• Flow takes place under the force of gravity
• Flow takes place due to the slope of the bed of the
channel only
• The Hydraulic gradient line coincides with the free surface
of water

3. Classification of OFC
• Steady and Unsteady Flow
• Uniform and Non uniform flow
• Laminar and Turbulent Flow
• Sub critical, Critical and Super critical flow

4. Steady flow and unsteady flow

6. Uniform flow and Non Uniform flow
If for a given length of the channel, the
• Velocity, depth, slope and cross section
remains constant – Uniform
• Velocity, depth, slope and cross section
doesnt remain constant – Non Uniform

7. Non Uniform flow (Varied Flow)
• Rapidly Varied Flow ( R V F)
• Gradually Varied Flow ( G V F)

8. Non Uniform flow (Varied Flow)
• Rapidly Varied Flow ( R V F)
• Depth of flow changes abruptly over a small
length
• Obstruction in the path of flow of channel
• Gradually Varied Flow (G V F)
• Flow in the channel changes gradually over a
long length of the channel

9. Laminar Flow and Turbulent Flow

10. Critical, Sub C and Super C flow

11. Discharge through open channel by
Chezy`s Formula

12. Discharge through open channel by
Chezy`s Formula

13. Discharge through open channel by
Chezy`s Formula

14. Discharge through open channel by
Chezy`s Formula

15. Problems on OCF using Chezy`s Constant

16. Problems on OCF using Chezy`s Constant

18. Problems on OCF using Chezy`s Constant