Contribution on transient flow modelling in storm sewers

Currently, the Preissmann slot model still enjoys popularity in modelling the transition between free-surface and fully pressurised flows in tail-race tunnels. However a fully dynamic and transient modelling technique is needed to predict the surge front location and velocity, the pressure rise in the full flow zone and the water depth change in the free-surface zone. In this paper, the transient flow is modelled and only one surge front is considered. Three 1-D models, which differ from each other by the computational method used to calculate either the free-surface or the full flow conditions, have been developed and applied successfully to both laboratory and field data. Predictions have been compared to measurements and good agreement found. Comparison between the three fully dynamic models was done and selective criteria were forwarded.