NUMERICAL-SIMULATION OF UNSTEADY-FLOW AT OPEN CHANNEL JUNCTIONS

In this work, some considerations about the problem of the unsteady flow simulation at a junction of open channels are presented. When simulating unsteady flow through junctions, the usual technique is to assume the equality of water stages. Following the theory of characteristics, we explain that this is a valid approximation for low Froude numbers but impossible to apply in other general cases. A theoretical approach of the steady state at a junction is used to state the unsteady compatibility conditions to be used. A time evolution modelling including supercritical flows, hydraulics jumps and shock propagation through the junction becomes possible and a useful tool to improve complex dam break simulations involving tributaries.