(SEM V) THEORY EXAMINATION 2023-24 OPEN CHANNEL FLOW

Subject Code: KCE053

Subject Name: Open Channel Flow

Course: B.Tech (Semester V)

Maximum Marks: 100

Duration: 3 Hours

Exam Year: 2023–24

Sections: A, B, and C

SECTION A – Short Answer Questions (2 × 10 = 20 Marks)

Attempt all questions briefly.

a. Differentiate between prismatic and non-prismatic channels.
b. What are the types of flow in open channels?
c. Define critical depth and normal depth.
d. Write the differences between Gradually Varied Flow (GVF) and Rapidly Varied Flow (RVF).
e. Differentiate between jump and surge.
f. Define energy dissipater.
g. What is spatially varied flow (SVF)?
h. Define bottom racks.
i. Which factors affect the flow through a culvert?
j. Explain constrictions in open channels.
 

SECTION B – Medium-Length Questions (10 × 3 = 30 Marks)

Attempt any three of the following.

Derive the relationship between critical depth and specific energy for a rectangular channel.

Explain the standard fourth-order Runge–Kutta method to solve the GVF differential equation.

Discuss positive and negative surges in open channels — causes, effects, and mitigation.

Explain the fundamental principles of Spatially Varied Flow (SVF) and its real-world applications.

Discuss the importance of velocity design in culverts and describe the main components with a neat sketch.
 

SECTION C – Long / Analytical Questions (10 × 5 = 50 Marks)

Q3. Channel Geometry

a. Explain the most efficient channel and derive the condition for a rectangular section.
OR
b. Describe flow properties in open channel flow.

Q4. Gradually Varied Flow (GVF)

a. Derive the equation governing GVF and discuss its assumptions and limitations.
OR
b. A rectangular channel, 7.5 m wide, flows at 2 m depth with bed slope = 1/3000.

A weir raises the water surface by 0.75 m at the downstream end.

Find the water surface slope at the section (Manning’s n = 0.02).

Q5. Rapidly Varied Flow (RVF)

a. Explain the characteristics of RVF and the conditions under which hydraulic jumps occur.
OR
b. In a hydraulic jump in a 3 m wide channel, discharge = 7.5 m³/s, pre-jump depth = 0.28 m.

Calculate sequent depth and energy loss.

Q6. Spatially Varied Flow (SVF)

a. A 2 m wide channel carries 3.5 m³/s discharge at Froude = 0.30.

A 2 m long bottom rack with E = 0.2 is installed; flow becomes supercritical.

Estimate the discharge diverted out.
OR
b. Discuss classifications and solutions of SVF — explain two classifications and their effect on flow profiles.

Q7. Non-Prismatic Flow

a. Explain transition between subcritical and supercritical flow.
OR
b. Discuss the significance of non-prismatic channel sections — include two design considerations and their impact on flow characteristics.
 

Key Topics to Prepare

Basic Concepts

Prismatic vs Non-Prismatic channels

Types of flow: Steady, Unsteady, Uniform, Non-uniform, Laminar, Turbulent, etc.

Critical depth, specific energy, and Froude number.

Gradually Varied Flow (GVF)

GVF equation derivation and assumptions.

Classification of GVF profiles (Mild, Steep, Critical, etc.).

Runge–Kutta method for profile computation.

Rapidly Varied Flow (RVF)

Hydraulic jump — types, characteristics, energy loss.

Surges — positive and negative; causes and control measures.

Spatially Varied Flow (SVF)

Definition, equations, and classification (increasing/decreasing discharge).

Practical examples — side weirs, bottom racks, spillways.

Non-Prismatic Channels

Significance in transitions and curved sections.

Flow behavior and design considerations in non-uniform geometry.

Culverts and Constrictions

Components and design importance.

Factors affecting discharge and flow control in culverts.

Study Tips

Derivations are key — focus on GVF, RVF, and specific energy relations.

Practice numerical problems on hydraulic jumps, critical depth, and flow transitions.

Draw clear sketches for channel sections, jumps, and flow profiles.

Revise Froude number relations — use to identify flow regimes.

Understand applications — spillways, culverts, transitions, side weirs.