Numerical simulation of drainage network flows based on Godunov scheme

Conventional drainage network models that use the link-node approach often fail to simulate the detailed internal flow processes in drainage pipes. To address the problem, a one-dimensional drainage network hydrodynamic model based on a Godunov-type finite volume scheme and the Preissmann slot theory was proposed in the present work. The Harten-Lax-van Leer (HLL) approximate Riemann solver was employed in the model to calculate the numerical flux at the cell interfaces, the impacts of the water levels at the nodes of the pipeline on the connected pipes were identified, and the water levels were calculated and updated by the strict mass conservation equation and the theory of characteristics. Verification on three classical computation examples proved that the proposed model achieved accurate and stable performance in simulating pressured transient flows, transient mixed flows, and other complex flow regimes. The model was applied to simulation of rainwater drainage at Tianfuheyuan Community in Xixian New District, Shaanxi, China, and the simulation results agreed with the measured data. The proposed model can be used to identify the hydrodynamic factors at the central node of all computation cells and junctions of the pipeline, and is hence expected to provide a basis for detailed simulation of urban pluvial flooding.