An unstructured 3D LES solver for free surface flow and breaking waves

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 hydrodynamie 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 2D 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 3D 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. A novel, coupled Volume Of Fluid (VOF)/Level Set (LS) interface capturing scheme for the prediction of violent free-surface flows is presented in this study. This method will be integrated into a well validated 3D unstructured finite volume (FV) based solver to investigate breaking waves in the surf zone. Furthermore, large-eddy simulation (LES) will be employed to predict the turbulence.