Incipient Hydraulic Jump at Channel Junctions

The conditions for hydraulic jump formation at the confluence to a supercritical flow are examined theoretically. One‐dimensional analysis for rectangular channels leads to approximate criteria for the channels discharge ratio in terms of the junction geometry and approaching flow conditions. The effect of the main factors, notably the Froude numbers and channels' width ratio, is determined. Experiments are carried out for junctions at a 90° and a 17° angle of a subcritical tributary flow to a weakly supercritical main flow with F1=1.5-2.0. The results of this study and other available experimental results covering a wider range of Froude numbers compare favorably to the theoretical predictions. The behavior of the water level at the end of the lateral channel is also presented in nondimensional diagrams.