A study on spatial variation of water flow at confluence connected to non-orthogonal channels

Most studies on the flood flow characteristics at a confluence focus on channels connected orthogonally or at right angle, but studies on non-orthogonally connected channels remain limited. In this study, hydraulic-model experiments and numerical simulations are conducted to analyze the spatial variation of water flow in and around a confluence connected to non-orthogonal channels. Comparison of the measured and simulated water depth distributions in and around the confluence indicates that the results are in relatively good agreement. In the experiment where the angle between two upstream channels is 45°, the water flow pattern in and around the confluence corresponds approximately to Type I proposed by (Mignot et al. J Hydraul Res 46:723–738, 2008). However, it was found that there is no any flow type to correspond to the water flow pattern measured in the case of the angle of 135°. For analyzing the variation of the water depth in and around the confluence with inflow, numerical simulation is performed by setting the inflow ratio of the two inlet channels to one, three, and six, respectively.