OPEN CHANNEL SURGES AND ROLL WAVES FROM MOMENTUM PRINCIPLE

The classification of rapidly varied unsteady flow is reviewed from continuity and momentum equations. Non-dimensional equations are proposed for analysing the combinations of sub- or supercritical regimes in the up- and downstream flow in a surge. A continuous profile or an alternative surge combination is found when Fr > 2. It is shown that a simpler approach of the roll wave phenomenon can be obtained from a finite momentum equation.