Two-dimensional shallow water flow modeling based on an improved unstructured finite volume algorithm

Abstract

An improved finite volume algorithm is proposed for modeling the free surface flows. The effects of variable reconstruction and treatments for partially wetted cells on numerical oscillations are demonstrated through a complex field-scale simulation. Results show that the combination of a vertex-based slope limiting approach and an updating strategy that the continuity and momentum equations should be simultaneously updated for partially wetted cells is essential to prevent unphysical oscillations. In this situation, the bed slope terms in wetted cells are exactly discretized, whereas the divergence-form-based approach is adopted for partially wetted cells. This new hybrid method provides an alternative way that precisely preserves the well-balanced property. A practical application of realistic dam-break flood propagation is presented. It is found that the model is free of numerical oscillation and can accurately predict dam-break flows over complicated topography with wetting and drying.