D B4D353 Pages: 2

b. A trapezoidal irrigation channel, having side slopes 3 horizontal to 2 vertical, is to carry a
flow of 10 cumecs on a longitudinal slope of 1 in 5000. The channel is to be lined for
which the value of Manning’s coefficient is 0.012. Find the dimensions of the most

economic section of the channel. (10)

6. Derive the expression for conjugate depths and energy loss associated with hydraulic jump
in rectangular channels. PART ^

Answer any 2 questions. Each question carries 20 marks.

7. a. Derive the dynamic equation of gradually varied flow in a channel, stating the

assumptions involved. (10)

b. A rectangular channel of 8.0 m wide has a uniform depth of flow of 2.0 m and has a
bed slope of 1 in 3000. If due to weir constructed at the downstream end of the channel,
water surface at a section is raised by 0.5m, determine the water surface slope with respect
to horizontal at this section. Assume Manning’s n= 0.02. (10)
8. a. Explain, with sketches, the various surface profiles that are possible in an open channel.
(12)
b. Derive the equation for the computation of length of backwater curve by step method.
(8)
9. For laminar flow in a pipe, the pressure drop AP in pipe of diameter D and length L
depends on the density ‏م‎ and viscosity ப of the flowing fluid, mean velocity of flow ५
and the average height of surface roughness of pipe (t). Show by Rayleigh’s method, the p
ressure drop AP is given by

AP =p V°f[(L /D) (0) (n/p V D)] (20)

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