Design of Open‐Channel‐Contraction Tranisitions

Abstract

Open-channel contractions for subcritical flows are encountered in the design of many hydraulic structures in which flow is flumed for reasons of economy. In all the works associated with fluming of canals, suitable transitions are necessary to minimize the head losses. Existing knowledge of the design of contraction transitions is inadequate because no attention is paid to minimizing the head loss. In this note, applying optimal-control theory, a methodology for design of contraction transition for a subcritical flow has been developed. Analyzing a large number of optimally designed transitions, empirical equations for bed width, side slope, and bed-elevation profiles have been obtained. It is hoped that these equations will find use in the design of fluming structures.