Power-law free overfall in subcritical flow regime

Abstract Free overfall can be used as a discharge measuring structure by a single measurement of end flow depth. Many theoretical and experimental studies carried out on free overfalls with different cross-section shape, different slope (mild and steep), and different roughness. However there is not any study for prismatic free overfalls with power-law cross section. This research presents a theoretical end-depth ratio (EDR) and a theoretical end depth-discharge (EDD) relationship for a free overfall located in a horizontal open channel with power-law section. The power-law section is a general section which reduces to the commonly used rectangular, parabolic, and triangular sections. Direct solutions are proposed by simulating the free overfall as a weir without crest in subcritical flow regime. Experimental and theoretical results are then used to verify the proposed relationships. The proposed relationships show excellent agreement with the experimental results.

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