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INPUT   DATA

♥ EXAMPLE Of Input/Output

Title

Bottom width, w		m
Slope of bank #1, z1
Slope of bank #2, z2
Slope of channel, S
Depth of flow, d		m
Manning coefficient, n

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OUTPUT   VARIABLES   &   GRAPHS

Variables	Values	Units
♦  Flow rate or discharge, Q		m3/s
♦  Flow velocity, V		m/s
♦  Top width, T		m
♦  Channel area, A		m2
♦  Wetted perimeter, P		m
♦  Hydraulic radius, R		m
♦  Froude number, F

Uniform Flow Of Water In A Trapezoidal Channel

Open channel flow is flow of a liquid with a free surface, where the free surface is at atmospheric pressure. The flow takes place under the force of gravity. That is, it takes place due to the slope of the channel bed and the hydraulic gradient coincides with the free surface of water. Many natural and man-made channels are approximately trapezoidal in cross-section.
The most common method for determining the behavior of open channel flow is Manning's variation of the Chezy equation: :

where
     Q = discharge rate
     V = mean velocity of flow
     d = depth of flow
     w = width of bed of channel
     z₁ = slope of bank 1, horizontal to vertical
     z₂ = slope of bank 2, horizontal to vertical
     S = slope of channel, vertical to horizontal
     θ = slope of channel in degrees
     T = top width of surface of flowing water
     P = wetted perimeter of cross-section
     R = hydraulic radius of flow cross-section
     n = Manning's roughness coefficient
     F = Froude number: F < 1 => subcritical flow, F=1 => critical, F>1 supercritical

Tips

    ◊ Use link EXAMPLE Of Input/Output  to demo data entry expectations and results; you may edit & use it as starting point

BIBLIOGRAPHY

• Lindeburg MR; 101 Solved Civil Engineering problems; Professional Publications, Inc., Belmot, CA, USA, 2001.
• Hicks TG; Civil Engineering Formulas, Pocket Guide; McGraw Hill, New York, 2002.
• Chaudhry, MH; Open Channel Flow, Prentice-Hall, Inc., Englewoood Cliffs, NJ, 1993