DAR Engineering and Associates

Open Channel Flow Manual


TABLE OF CONTENTS

    SECTION 1: GENERAL REVIEW OF HYDRAULICS

    • Principles of Fluid Mechanics

    • Equations for Open Channel Flow
    • Crossectional Properties for Prismatic Channels
    • Calculation of Uniform Depth for Prismatic Channels
    • Calculation of Critical Depth
    • Alternative Forms of Simplified Manning's and Critical Depth Equations for Prismatic Channels
    • Points of Control and Flow Regimes in Open Channels
    • Freeboard In Open Channels
    • Sewer/Storm Drain Design
    • Methodology for Analyzing Open Channel Flow Problems
    • Conceptual Model for Open Channel Flow
      • PROBLEM: Normal Depth, Critical Depth, and Flow Regime for Trapezoidal Channel
      • PROBLEM: Normal Depth, Critical Depth, and Flow Regime for Rectangular Channel
      • PROBLEM: Normal Depth, Critical Depth, and Flow Regime for Circular Channel
      • PROBLEM: Storm Drain Design
      • PROBLEM: Sanitary Sewer Design
      • PROBLEM: Calculation of Normal and Critical Depths for Non-Prismatic Channel
      • PROBLEM: Drop in Invert Elevation
      • PROBLEM: Flow in a Gutter
      • PROBLEM: Drainage Channel

    SECTION 2: ENERGY EQUATION

    • Importance of Energy Equation in Open Channel Flow Problems

    • Specific Energy
    • Relationships for Critical Depth in Rectangular Channel
    • Examples of Specific Energy Principle Applied to Open Channel Flow Problems
    • Specific Energy for Constant Head
      • PROBLEM: Maximum Rise in Invert Elevation for Broad Crested Weir
      • PROBLEM: Maximum Width at Outlet of Transition Connecting Two Rectangular Channels
      • PROBLEM: Transition Design Rectangular to Circular Channel
      • PROBLEM: Energy Losses and Hydraulic Grade Line
    • Calculation of Critical Depth for Any Type of Channel Crossection Assuming Uniform Velocity Distribution
    • Summary of Principles for Specific Energy

    SECTION 3: WATER SURFACE PROFILES IN PRISMATIC CHANNELS

    • Why Are Water Surface Profiles Important in Analyzing Open Channel Flow Problems?

    • Water Surface Profile Computations
    • Derivation of Water Surface Profile Equation
    • Water Surface Profiles
      • PROBLEM: Sketch Water Surface Profiles
    • Derivation of Direct Step Method for Calculating Water Surface Profiles
    • Procedures to Calculate Water Surface Profiles in Prismatic Channels
    • Guidelines to Ensure Water Surface Profiles Are Calculated Correctly
      • PROBLEM: Water Surface Profile for Rectangular Channel
      • PROBLEM: Water Surface Elevation in Reservoir
      • PROBLEM: Water Surface Profile in Circular Channel
      • PROBLEM: Freeboard for Design of Rectangular Channel

    SECTION 4: MOMENTUM PRINCIPLE

    • Why Is the Momentum Principle Important in Analyzing Open Channel Flow Problems?

    • Generalized Momentum Equation for Steady State Flow
    • Hydraulic Jumps in Open Channels
    • Momentum Equation Applied to Hydraulic Jumps
    • Analysis of Hydraulic Jumps With Breaks in Invert Slope
    • Energy Losses Through Hydraulic Jump
    • Length of Hydraulic Jumps in Horizontal Channels
      • PROBLEM: Hydraulic Jump in Rectangular Channel
      • PROBLEM: Hydraulic Jump and Water Profile
      • PROBLEM: Jump Analysis and Water Surface Profile in Rectangular Channel
      • PROBLEM: Hydraulic Jump in Trapezoidal Channel
      • PROBLEM: Hydraulic Jump in Trapezoidal Channel With Grade Break
      • PROBLEM: Radial Gate and Hydraulic Jump
      • PROBLEM: Force On Gate
      • PROBLEM: Hydraulic Jump with Invert Change in Elevation

    SECTION 5: CONCEPT OF MOST EFFICIENT OR BEST HYDRAULIC CROSSECTION

    • Most Efficient or Best Hydraulic Crossection

    • Best Hydraulic Crossections for Design (Depth = Normal Depth)
    • Summary Equations to Calculate normal Depth for Best Hydraulic Sections
    • Other Engineering Considerations for Best Crossection
      • PROBLEM: Best Hydraulic Section for Rectangular Channel
      • PROBLEM: Best Hydraulic Section for Trapezoidal Channel
      • PROBLEM: Best Design Section for Top Width Limitation
      • PROBLEM: Design Depth for Best Crossection

    SECTION 6: WEIR FLOW

    • Weir Flow

      • PROBLEM: Weir Flow