Subcritical open channel flows in four branch intersections

Subcritical flow in an intersection composed of four similar orthogonal channels has been studied experimentally in a configuration with two inflows and two outflows for a wide range of experimental conditions. The results have been used to develop a relationship between the incoming flow rates and the flow distribution in the two outlet channels, based on the conservation of discharge and momentum in the intersection, and suitable stage‐discharge relationships for the downstream controls in the outflow channels. A final equation is provided by an empirical correlation for the outflow in one of the channels, based on the experimental data obtained from these experiments; this correlation agrees with all the available data to within ±5%. It is shown how the resulting set of equations can be used to compute the discharge distribution in any similar intersection, given the incoming flow rates and some form of stage‐discharge relationship for the outlet conditions. Key Points Possible transposition of some results from three to four branch configurations Empirical correlation based on a large number of experimental results Tool to calibrate or validate numerical simulations applicable to all geometries