3D numerical simulation of the interaction between waves and a T-head groin structure

The aim of coastal structures for the defense from erosion is to modify the hydrodynamic fields that would naturally occur with the wave motion, to produce zones of sedimentation of solid material, and to combat the recession of the coastline. T-head groin-shaped structures are among the most adopted in coastal engineering. The assessment of the effectiveness of such structures requires hydrodynamic study of the interaction between wave motion and the structure. Hydrodynamic phenomena induced by the interaction between wave motion and T-head groin structures have three-dimensionality features. The aim of the paper is to propose a new three-dimensional numerical model for the simulation of the hydrodynamic fields induced by the interaction between wave fields and coastal structures. The proposed model is designed to represent complex morphologies as well as coastal structures inside the domain. The numerical scheme solves the three-dimensional Navier-Stokes equations in a contravariant formulation, on a time-dependent coordinate system, in which the vertical coordinate varies over time to follow the free-surface elevation. The main innovative element of the paper consists in the proposal of a new numerical scheme that makes it possible to simulate flows around structures with sharp-cornered geometries. The proposed numerical model is validated against a well-known experimental test-case consisting in a wave train approaching a beach (non-parallel with the wave front), with the presence of a T-head groin structure. A detailed comparison between numerical and experimental results is shown.