Preliminary Development of a One-Dimensional Depth-Averaged Flow Model for the Simulation of Flow over Porous Surface

Abstract.

In recent years, the Sustainable Urban Drainage system (SuDs) or Green Infrastructure (GI) are receiving increasing attention and popularity in the management of storm water in urban area. Based on the philosophy of increasing the time of concentration of surface runoff through interception, infiltration and storage at site, most of SuDs or GI components such as the filter strip, swale and pervious pavement involve the process of flow over porous surface. This paper presents a preliminary work of the development of a numerical model for the simulation of flow over porous surface. The porosity of the porous surface ranges from 0.35-0.40 and maintained under unsaturated condition. The numerical model solved the unsteady one-dimensional Saint-Venant equation. The advection term in the momentum equation was solved using the Constrained Interpolation Profile (CIP) scheme which is of the third order accuracy. In this preliminary study, the infiltration process is modelled as a constant rate where its value was determined from the experiment. The numerical model was initially verified against the analytical solution of idealized dam-break flow by comparing the propagation of front wave and overall flow surface profile. An experiment was carried out where a finite water body retained behind a dam was released instantaneously onto porous bed at the downstream of the dam gate. The flow surface profile and front propagation were recorded and used for validation of the numerical model. It was found that the numerical model performed satisfactorily in terms of the reproduction of flow profile with flow even when constant infiltration rate was used.