E4 Questions on Gradually varied flow: Flow Transitions.
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E4.1
A wide channel consists of two long reaches. The upstream reach has a bed slope of 1 in 100 and the downstream reach has a bed slope of 1 in 1500. The Chezy C for both lengths can be assumed constant and equal to 45. Determine the profile that occurs when the flow per unit width is and determine whether a hydraulic jump occurs and if one occurs which reach of the channel it occurs.
(Answers: , , . Jump in reach 1.) -
E4.2
A long wide channel consists of an upstream section with a bed slope of 0.025 and a downstream section with a bed slope of 0.0002. The Chezy C is constant for the whole of the channel and equal to 40 in SI units. When the discharge in the channel is . width demonstrates that a hydraulic jump occurs. Determine in which reach of the channel the jump occurs. Complete your answer with a free-hand sketch of the final profile and label each of the gradually varied profiles.
(Answer: , , , , ) -
E4.3
A wide channel has three reaches each with a different slope. Each can be considered to be long and at the downstream end of the three reaches there is a free outfall. For a specific case, the Chézy C value for all reaches is 32 and the flow per unit width is . The upstream reach has a slope of 1-in-500, the middle reach has a slope of 1-in-50 and the downstream reach has a slope of 1-in-2,000. Determine which flow profile occurs.
(Answer: , , , , , ) -
E4.4
A wide channel has two reaches with different bed slopes changing from to . Both reaches have the same cross-section shape and bed roughness of . Sketch the critical flow depth line, uniform flow depth lines, and water surface profile in the channel and identify the type of water surface profile, if the flow discharge per unit width is .
(Answer: , , , M1 profile ) -
E4.5
A wide channel consists of three long reaches. The upstream reach has a bed slope of 1 in 500, the middle reach a slope of 1 in 50, and the downstream reach slope of 1 in 1,750. The Chezy C for all three lengths can be assumed constant and equal to 27. Determine the profiles that occur if the flow per unit width is .
(Answer: , , , , , . Jump in reach 2 (middle). )