A Novel Method for Gradually Varied Subcritical Flow Simulation in GeneralChannel Networks

摘要

A novel method is proposed for subcritical flow modeling in channel networks usingthe implicit finite-difference method which prevails in simulating gradually variedflows. The method is proposed to take account of the backwater effects at thejunction points based on junction-point water stage prediction and correction(JPWSPC) and is applicable to flows in both looped and non-looped channelnetworks, even if the flows are tidal. The method is implemented in a numericalmodel, in which the Saint-Venant equations are discretized using the four-pointimplicit Preissmann scheme and the resulting nonlinear system of equations is solvedusing the Newton-Raphson method. The solving procedure has no difference frommodeling single branches one by one except for simple junction-point water stageprediction and correction, which guarantees the simplicity, efficiency and robustnessof the JPWSPC method. The model is applied to two hypothetic channel networksand a real river network in the south of China. All the networks are branched and alsolooped. Great agreement between the results and those from literature or observeddata reveals the accuracy.