Open Channel Transitions

Transitions connect conveyance structures of different types or with different characteristics. The rapidly varied flow through subcritical transitions is analysed by application of energy and momentum conservation, with empirical input to account for energy loss. Designs to reduce energy loss are advantageous for contractions, but for expansions will increase the boundary shear stress and the extent of the gradually varied profile upstream. Supercritical transitions present problems of wave formation. Formulations are presented for the shock wave front direction and height for straight wall transitions and the variation of depth along the wall in curvilinear transitions. A graphical method for designing straight wall transitions to suppress wave propagation is presented.