Chapt10

# If the channel is horizontal with n 0018 and there is

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Unformatted text preview: . Compare your results with the discussion in Prob. 10.104. Let S0 0.005. P10.109 Figure P10.109 illustrates a free overfall or dropdown flow pattern, where a channel flow accelerates down a slope and falls freely over an abrupt edge. As shown, the flow reaches critical just before the overfall. Between yc and the edge the flow is rapidly varied and does not satisfy gradually varied theory. Suppose that the flow rate is q 1.3 m3/(s m) and the surface is unfinished cement. Use Eq. (10.51) to estimate the water depth 300 m upstream as shown. y? 2m 30 m3/s 3m L Reservoir P10.112 P10.113 Figure P10.113 shows a channel contraction section often called a venturi flume [19, p. 167], because measurements of y1 and y2 can be used to meter the flow rate. Show that if losses are neglected and the flow is one-dimensional and subcritical, the flow rate is given by Q 2g(y1 y2) 1/(b2 y2) 1/(b2y2) 22 11 1/2 Apply this to the special case b1 3 m, b2 2 m, and y1 1.9 m. (a) Find the flow rate if y2 1.5 m. (b) Also find the depth y2 for which the flow becomes critical in the throat. S0 = 0.06° b1...
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