Numerical Modelling of Flood Waves Propagation in Sewer Networks using one- and Two-Dimensional Modified HLLC Method

Modelling of flood waves within surface and subsurface network is quite complicated. This complexity is mainly with respect to different flow regimes propagation into the sewer network which interacts with each other at connections between underground networks. The main purpose of the present paper is modelling and hydrodynamic prediction of these types of bore interactions using the shallow water equations. The shallow water equations are then solved using a second-order accurate HLLC Riemann which is able to model the wave propagation over wet and dry states based upon a combination of particular Riemann wave speeds. Friction terms are treated in a separate way within the associated source terms. First, the numerical solver is employed to model the shock and rarefaction waves over the wet and dry states and the achieved numerical results are compared with the exact solution. Then, the effect of friction terms for the one-dimensional dam failure propagation over wet and dry bed is considered and the computed results are compared with the STAR-CD which is a Navier-Stokes solver. Finally, two-dimensional flood wave propagation is modelled within a rectangular sewage section and the obtained results are validated with the three-dimensional STAR-CD results. The numerical results demonstrate that the defined numerical solver in both one and two-dimensional provides very good agreement with the exact solution and Navier-Stokes solver.