Experimental and numerical investigation of water-surface characteristics at crossing connected non-orthogonally to four flat channels

Most studies on the flood flow characteristics at a crossing 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 performed to analyze the characteristics of the water-surface variation in and around a crossing connected non-orthogonally to four flat channels. Comparison of the measured and simulated water depth distributions in and around the crossing 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 crossing corresponds approximately to Type I proposed by Mignot et al. (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 crossing with inflow, numerical simulation is performed by setting the inflow ratio of the two inlet channels to one, three, and six, respectively.