Phone: 337-475-5874
Fax: 337-475-5286
Box 91735
Lake Charles, LA 70609
engineering@mcneese.edu http://mcneese.edu/ceet/eng

Civil Engineering - CIEN 404

Open Channel Hydraulics

• Classify open channel flows as steady or unsteady, uniform or nonuniform (gradually and rapidly varied), and spatially varied
• Develop governing equations of fluid mechanics (conservation laws of mass, energy, and momentum) with modification due to the free surface
• Calculate the momentum flux correction coefficient (b) and the kinetic energy flux  correction coefficient (a) for open channel flows
• Distinguish surface and form resistance. 
• Review principles of dimensional analysis (i.e., application of Buckingham Pi Theorem)
• Define specific energy (E)
• Develop a specific energy diagram for open channel flow problems
• Develop generic critical depth relationships by differentiating the expression for specific energy and setting the result to zero
• Compute critical flow depth (yc) for a given channel geometry (i.e., rectangular, trapezoidal, circular, etc.) and flow rate
• Establish connection between critical flow depth and Froude number
• Use the Froude number to define subcritical and supercritical flow regimes
• Examine the limiting choke condition for open channel transitions (bottom step and contraction)
• Compute energy losses due to contractions and expansions
• Develop discharge relationships for sharp-crested and broad-crested weirs
• Apply conservation of momentum to a hydraulic jump formed in a horizontal rectangular channel
• Define the momentum function for different channel geometries
• Compute sequent depth ratios for different channel geometries
• Develop momentum function diagrams and illustrate the effect of obstructions (e.g., baffle blocks)
• Analyze simple surge problems by transformation to steady flow conditions
• Compute the backwater effects due to bridge piers
• Develop a relationship (using momentum analysis) for average shear stress on the boundary of a uniform flow
• Examine the development of the Chezy and Manning uniform flow formulas
• Identify factors affecting open channel flow resistance (e.g., channel shape, unsteadiness, etc.)
• Compute composite channel roughness
• Compute normal flow depth with Manning’s equation for various channel geometries and channel conditions (slope, roughness, and discharge)
• Design rip-rap lined and grass-lined open channels
• Compute critical channel slope and classify channel slopes as steep or mild
• Design open channels to be hydraulically most efficient (i.e., best hydraulic section)
• Develop the gradually varied flow equation
• Classify water surface profiles (i.e., M1, M2, M3, S1, S2, S3, H1, H2, C1, C2, A1, A2)
• Sketch composite flow profiles for a variety of flow situations
• Analyze variations of the lake discharge problem
• Perform water surface profile computations using the direct step method and various numerical solution techniques (corrected Euler, Runge Kutta)
• Apply the standard step method to compute water surface profiles in natural channels
• Review possible culvert flow regimes and distinguish between inlet and outlet control
• Develop head-discharge relationships for various culvert flow regimes
• Plot a performance curve for a culvert
• Design a culvert to carry a specified design discharge (e.g., 100-year flood discharge)
• Use the computer model HEC-RAS (Hydrologic Engineering Center – River Analysis System) to compute water surface profiles for artificial and natural channels with and without hydraulic structures (bridges and culverts)

Prepared by Dr. Jason Hill