DEPTH-AVERAGED NUMERICAL SOLVER OF MEANDERING RIVER FLOWS BY CIP-SOROBAN GRIDS IN CYLINDRICAL COORDINATE SYSTEM

摘要

A new numerical solver is developed for a shallow-water flow model to simulate meandering river flows. This solver can investigate flows in curved river channels by means of the adaptive CIP-Soroban (CIP-S) scheme in a cylindrical coordinate system. Time development of depth-averaged water velocity and free-surface level is computed in the cylindrical (or orthogonal curvilinear) coordinate system without any transformation of the governing equations, and the advection term is calculated by the high-accuracy CIP scheme. The numerical accuracy of such a solver can be verified by the pure convection tests proposed by Zalesak and also examined by applying to a virtual meandering river flow. In comparison with the original CIP-S method in a Cartesian coordinate system as well as the boundary fitted coordinate (BFC) method, findings show that the proposed numerical solver performs well and that it can reasonably predict the main flow profile and water surface elevation.