Ability of Preissmann slot scheme to simulate smooth pressurisation transient in sewers

摘要

Urban drainage networks are generally designed to operate in a free-surface flow condition.nHowever, as a consequence of heavy rainfall events or network malfunctions, the filling of sewersn(pressurisation) and network overflow may occur. Several modelling software products arencommonly used to simulate floods in drainage networks, and their results are usually thoughtnto be reliable and robust. However, no specific studies have been carried out on the behaviournof these modelling products during the pressurisation transition. Mathematical models often usenthe Preissmann slot concept to handle pressurisation. In this paper, on the basis of laboratorynpipe tests, the reliability of such a scheme is studied by means of a popular and open-sourcensoftware product: SWMM (Storm Water Management Model). Many numerical tests were carriednout with SWMM, varying the spatial and time steps and the Preissmann slot width, in order tonexamine the performance of the modelling software over intervals of these parameters evennwider than what is usual in practical applications. The comparison between simulated andnexperimental surges allows one to draw interesting conclusions regarding the effectivenessnof software products analogous to SWMM in simulating pressurisation, as well as the choicenof the parameters themselves.