# Open Channel Flow

In Open Channel Flow, we studied a total of six chapters, which are as follows:

**Chapter 1:**Open Channel Flow – Introduction**Chapter 2:**Uniform Flow**Chapter 3:**Energy-Depth Relationship**Chapter 4:**Gradually Varied Flow**Chapter 5:**Rapidly Varied Flow: Hydraulic Jump**Chapter 6:**Unsteady Flow: Surge

## Open Channel Flow – Introduction: 1

**Open Channel Flow**, Difference Between Open Channel Flow and Pipe Flow, **Type of Force In Open Channel Flow**– Inertia Force, Gravity Force, Viscous Force. Reynold’s Number, Froude Number.

**Different Types Of Open Channel:** **1. **On The Basis of Formation– Natural Channel, Artificial Channel. **2. **On The Basis Of Change In Properties Of Channel- Prismatic Channel, Non-Prismatic Channel. **3.** On The Basis Of Type Of Boundary– Rigid Boundary Channel, Mobile Boundary Channel

**Types of Open Channel Flow- **Steady & Unsteady Flows, Uniform and Non-Uniform Flows, Varied Flow- A. Gradually Varied Flow, B. Rapidly Varied Flow, C. Spatially Varied Flow

**Types of Non-uniform flows Or Varied Flow-** Gradually varied steady flow: Backing up of water in a stream due to dam, Gradually varied unsteady flow: Passage of flood wave in a river, Rapidly varied steady flow: A hydraulic jump below a spillway or a sluice gate, Rapidly varied unsteady flow: A surge moving up a canal breaking of wave on the shore, Spatially varied steady flow: Flow over side weir or flow over bottom rock, Spatially varied unsteady flow: Surface runoff due to heavy rainfall. Different Combination Of Flow

**Laminar and Turbulent flow- **Laminar Flow, Turbulent Flow. **Critical Flow, Subcritical Flow & Supercritical Flow, **Celerity (Co), **Geometric Element Of Channel Section- **Depth of Flow (y), Depth of Flow Section (d), Top Width (T), Wetted/ Water Area (A), Wetted Perimeter (P), Hydraulic Radius/ Hydraulic Mean Depth of Flow (R), Hydraulic Depth.

Velocity Distribution In Open Channel Flow, Kinetic energy correction factor (α), Momentum correction factor (β), **Pressure Distribution- **Case (i) Channel With Small Slope, Case (ii) Channel With Large Slope

**Different Equation Used In OCF – ****1**. Continuity Equation –(A). Continuity Equation For Steady Flow (Uniform Flow, GVF, RVF), (B). Continuity Equation For Steady Flow (SVF), (C). Continuity Equation For Unsteady Flow (GVF, RVF). **2**. Energy Equation, **3**. Momentum Equation In Open Channel Flow- For Steady Flow, For Unsteady Flow, **SPECIFIC FORCE.**

## Uniform Flow: 2

**Uniform Flow, **Analysis of Uniform Flow, **Chezy Equation- **Derivation From Darcy’s Weisbach Equation. **Manning’s Equation,** Relationship Between Chezy’s Constant & Friction Factor, Momentum Equation of Uniform Flow, **Most Economical Or Most Efficient Section of Channel, **

**Relationship Between Various Element To From An Efficient Channel Section- **1. Most Efficient Rectangular Section, 2. Most Efficient Triangular Section, 3. Most Efficient Trapezoidal Section– Case I: When side slope is fixed, Case II: When side slope is varied. 4. Most Efficient Circular Section- From Manning’s Equation, From Chezy’s Equation

**Properties of Most Efficient Channel Section of Different Shapes, ****Type of Channel According to Efficiency – **Type.1, Type.2.

**Shear Stress On The Boundary Of Uniform Flow In Open Channel Flow **

## Energy- Depth Relationship: 3

**Specific Energy**, **Relationship Between Specific Energy and Depth of Flow- **Case.1 When Discharge is Constant, Case.2 When Discharge is Variable.

**Calculation of the Critical Depth-** Critical Depth of Rectangular Section, Critical Depth of Triangular Section, Section Factor Z, Relation Between Discharge & Depth of Flow

**Channel Transition- ****Channel with a Hump (Flow Transition Due to Hump Creations)- **1. Subcritical Flow, 2. Super Critical Flow, Size of Maximum Hump For Critical Flow, Energy Loss due to Hump, **Transition With Reduction of Width in a Rectangular Channel (Flow Transition Due to Width Contraction)- **1. Subcritical Flow, 2. Supercritical Flow

## Gradually Varied Flow: 4

**Gradually Varied Flow, **Assumption In GVF,** Differential Equation of GVF,** Differential Energy Equation, **Classification Of Flow Profiles- **The slope of the channel can be classified as, Following Point Must Be Noted Before Studding the Characteristic of Flow Profile, Important Point.

**Practical Cases of GVF Profile- **(A) Type-M Profiles: M1 Profile, M2 Profile, M3 Profile. (B) Type-S Profiles: S1 Profile, S2 Profile, S3 Profile, (C) Type-C Profiles, (D) Type-H Profiles, (E) Type-A Profiles.

**Control Section, **Break In Grade, **Gradually Varied Flow Computation**–Direct Step Method, **Procedure For Computation of GVF Profiles **

## Rapidly Varied Flow: Hydraulic Jump: 5

**Rapidly Varied Flow, ****Hydraulic Jump**– Applications of Hydraulic Jump, Analysis of Hydraulic Jump. Momentum Equation for the Hydraulic Jump, **Hydraulic Jump in A Horizontal Rectangular Channel- **(A) Sequent Depth Ratio, (B) Energy Loss, (C) Relative Energy Loss, (D) Efficiency of Jump, (E) Height of Jump, (F) Length of Jump

**Classification of Jumps- **(i) Undular Jump (1.0 < F1 ≤ 1.7), (ii) Weak Jump (1.7 < F1 ≤ 2.5), (iii) Oscillating Jump (2.5 < F1 ≤ 4.5), (iv) Steady Jump (4.5 < F1 ≤ 9.0), (v) Strong or Choppy Jump (F1>9.0).

Velocity Profile For Hydraulic Jump, Jumps in Horizontal Non-rectangular Channels, Jumps on a Sloping Floor, Energy Dissipation, Location Of Jump

## Unsteady Flow: Surge: 6

**Introduction of Unsteady Flow**, Surges in Open Channel, **Type Of Surges- **(A) Positive Surge Moving Downstream, (B) Positive Surge Moving Upstream, (C) Negative Surge Moving Downstream, (D) Negative Surge Moving Upstream. **Analysis of Surges- **Case A- Positive Surge Moving Downstream Due to Sudden Open Sluice Gate, Case B- Positive Surge Moving Upstream Due to Sudden Closed Sluice Gate, **Celerity.**

## Topics

In Rapidly Varied Flow (R.V.F), a sudden change of depth occurs at a particular point of a channel and the change from one depth to another takes place at a distance of very short length.

Unsteady flow also called 'Transient Flow', occurs in the open channel when the discharge or depth or both vary with respect to time at a given section.