(SEM V) THEORY EXAMINATION 2022-23 OPEN CHANNEL FLOW

Course: B.Tech (Semester V)                                                         Subject: Open Channel Flow

Subject Code: KCE-053                                                                Duration: 3 Hours

Total Marks: 100

Instructions: Attempt all sections. Assume suitable data wherever required.

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

Answer all questions briefly:

Define specific force.

What do you understand by adverse slope?

Write the relation between water surface slopes and channel slope.

Draw a neat sketch of S₃ profile.

What do you understand by length of jump?

Define sills.

Give the classification of spatially varied flow.

Define bottom racks.

Define spiral flow.

What do you understand by constrictions?

Section B – Descriptive Questions (10 × 3 = 30 Marks)

Attempt any three:

Differentiate between normal depth and critical depth in open channel flow.

A rectangular channel (7.5 m wide) has a uniform depth of 2.0 m and a bed slope of 1 in 3000. If a downstream weir raises the water level by 0.75 m, find the water surface slope. Assume Manning’s n = 0.02.

In a 5 m wide rectangular channel, a hydraulic jump is formed with discharge 20 m³/s and pre-jump depth 0.5 m. Determine post-jump depth, Froude number, and energy loss.

State assumptions of the differential equation for spatially varied flow with increasing discharge.

With neat sketches, classify culvert flow with outlet unsubmerged conditions.

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

Attempt one part from each question:

Q3.
(a) A trapezoidal concrete channel carries 30 m³/s discharge with base width 5 m, side slopes 1V:2H, Manning’s n = 0.015, and bed slope = 0.001. Find normal depth of flow.
or
(b) For a trapezoidal channel of most economical section, prove that:

Half of the top width = length of one sloping side

Hydraulic mean depth = ½ × depth of flow

Q4.
(a) Explain the standard fourth-order Runge–Kutta method to solve the differential equation of gradually varied flow.
or
(b) Explain, with neat sketch, the graphical method for computing gradually varied flow.

Q5.
(a) Explain, with neat sketch, a positive surge moving downstream, and derive its expression.
or
(b) A hydraulic jump occurs in a horizontal triangular channel (1.5H:1V). The depths before and after the jump are 0.4 m and 1.5 m respectively. Estimate the flow rate and Froude number at the beginning and end of the jump.

Q6.
(a) A rectangular channel (2 m wide) carries a discharge of 3.5 m³/s at a Froude number of 0.30. A 2 m long parallel bottom rack with E = 0.2 is provided. Estimate the discharge diverted out under supercritical flow.
or
(b) A side channel spillway (100 m long, rectangular, 5 m wide) has n = 0.020, β = 1.30, and bed slope = 0.15. If the lateral inflow rate is 1.75 m³/s/m, find the critical depth and its location.

Q7.
(a) Explain the types of culvert flow with neat sketches and flow profiles.
or
(b) Write the conditions for simple analysis of flow characteristics, and derive the overall coefficient of discharge.