1D Analytical Model of the Subcritical Flow Distribution in Four- Branch Junctions of Open Channels

Prediction of flow distribution is necessary in open channels junctions at irrigation and conveyance water systems in order to design suitable plans and protect them in emergency situations. In this study, a one dimensional analytical model of subcritical flow distribution using mass - energy and momentum conservation laws was presented for a four-branch junction of open channels and compared with experimental results. The results showed that as the inlet discharge ratio and bed elevation of the lateral channels increased, the outlet discharge of the main channel increased. Furthermore, as the Froud number at the inlet of the main channel decreased, the outlet discharge of it increased. Changes in the height of the weirs at the end of the outlet channels had no considerable effect on the flow distribution. The maximum and minimum deviations of the flow amounts to the outlet lateral channel occurred at the angles of 60 and 90 degrees, respectively. Comparison of the analytical and experimental results showed a good agreement between them so that the maximum error was less than 10%.