Numerical investigation of swash zone hydrodynamics

This paper presents a novel numerical model using a fully three-dimensional (3D), incompressible, two-phase flow Navier-Stokes (NS) solver, which are discretized by the finite volume method. A high-resolution STACS-VOF method is used to capture the interface between the air and water phases. The validity of the simulation following this model is examined through 3D shear flow and collapsing cylinder of water. Then, this proposed model is adopted to simulate the dynamics of flow involved with surge bore propagating over a slope in the swash zone. The computed uprush shoreline motion and the tip of runup water surface agreed well with experimental data, which indicates that this model can describe the aerated flow accurately. Numerical analyses are also applied to the spatial and temporal distributions of free-surface, instantaneous flow field, and maximal bed shear stress in the bore collapse, uprush and backwash processes. The results from the analyses reveal that the flow dynamics is complicated after the bore breaks, and the proposed model can well capture the structure characteristics of sheet flow, which are better than the previous results. All these findings are of help to understand the pattern of sediment transport and coastal evolution in the swash zone.