Question

5. Given: Discharge = 400 cfs; upstream bottom width = 12 ft; upstream flow depth = 1 ft, downstream bottom width = 32 ft; length of transition = 100 ft. What should be the downstream flow depth (to an accuracy of 0.1 ft) for the hydraulic jump to occur approximately in the middle of the transition (Section 0 + 50)?

Answer 1

Discharge , bottom width and upstream depth is given which will help in findind velocity of flow in upstream. Further we will find the value of Fraud's number which will give the idea about flow type. At the end we will apply equation of hydraulic jump to find the depth of downstream.
Son Griven, Discharge = 400 cfo Width of upstream = 12 ft up stocam flow depth down Stocam width = 32 ft. 32 12 Rectangular in shape. Assuming both the sections are Froom Continuity a Q = AVI = A₂₂ - 400 cfs = 12x 1 x V V = 400 tt/sec And we know for Rectangular channel. day Vi Sg Y, = 5.87 fri 400/12 ſix 32.2 ft 1 sach is super critical and jumbo Por, 71 ie flow Will be occur.

At the same time We know that भ Y & Ye are sequent depth of Jump Than 1+ i +8F . Ч, Y, -1 +1 +8x15.8+)² ] g. · 1-1 + 1663] Yo = x + x 11563) = 7.816 ft. So, depth of flow in downstream will be 7.816ft As