A hybrid LS and VOF method for 3-D simulation of wave breaking and overtopping

The objective of this study is to determine wave overtopping, breaking, turbulence and streaming in the surf zone and thus analyze the performance of sea defenses and predict coastal flood risk in extreme conditions. Two-dimensional (2-D)| hydrodynamic models, based on structured grids, have gained prominence and been used for widespread applications in surf zone studies. Reasons for this include their relative simplicity to implement and low CPU time demand. However, the accuracy of predictions made by a 2-0 model may suffer from the neglect of the additional space direction. In addition, due to the difficulties posed by structured mesh schemes, surf zone geometries must be simplified before being transformed into the modeling domain, and many irregularly shaped structures have to be removed. Nowadays, the availability of greater computing power has driven the development of hydrodynamic models using 3-D unstructured meshes. Compared with its structured counterpart, the unstructured model has several attractive advantages such as: flexible modeling of complex geometries, convenient adaptive meshing capabilities and homogeneous data structures well suited for massively parallel computer architectures (Mavriplis, Pelaez and Kandil, 2001; Venkatakrishnan, 1995). This study presents a novel, coupled VOF (VOF) / LS (LS) interface capturing scheme for the prediction of violent free-surface flows. This method will be integrated into a well validated 3-D unstructured finite volume (FV) based solver (Zhao et al., 2001, 2002) to investigate wave breaking and overtopping over a structure. Further, large-eddy simulation (LES) is employed to predict the turbulence.