<P> A venturi flume is a critical - flow open flume with a constricted flow which causes a drop in the hydraulic grade line, creating a critical depth . </P> <P> It is used in flow measurement of very large flow rates, usually given in millions of cubic units . A venturi meter would normally measure in millimetres, whereas a venturi flume measures in metres . </P> <P> Measurement of discharge with venturi flumes requires two measurements, one upstream and one at the throat (narrowest cross-section), if the flow passes in a subcritical state through the flume . If the flumes are designed so as to pass the flow from sub critical to supercritical state while passing through the flume, a single measurement at the throat (which in this case becomes a critical section) is sufficient for computation of discharge . To ensure the occurrence of critical depth at the throat, the flumes are usually designed in such way as to form a hydraulic jump on the downstream side of the structure . These flumes are called' standing wave flumes' </P> <P> Venturi flumes have two advantages over weirs where the critical depth is created by a vertical constriction . First, the hydraulic head loss is smaller in flumes than in weirs . Second, there is no dead zone in flumes where sediment and debris can accumulate; such a dead zone exists upstream of the weirs . </P>

Difference between standing wave flume and venturi flume
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