Flow at 90° equal-width open-channel junction

This paper describes a one-dimensional approach to solving water depth upstream of a subcritical open-channel right-angled junction and to solving the contraction coefficient at the maximum flow constriction. The energy and momentum correction coefficients at the maximum flow constriction were found to be related to the inverse of the upstream-to-downstream discharge ratio of the main channel. The cross-sectional mean flow angle at the branch channel entrance was determined through detailed measurement of velocity vectors and was found to decrease as the discharge ratio increases. The shape index of the separation zone was also checked through observations of surface-dye trajectory and was found to agree with that obtained in previous studies. With known Froude numbers and the energy and momentum correction coefficients at the maximum flow constriction, the one-dimensional prediction and experimental results of this study correlate well to the data of other studies.