Simulating Oscillatory and Sliding Displacements of Caisson Breakwaters Using a Coupled Approach

Abstract

In this work, a computational fluid dynamics (CFD) model was coupled with a dynamic response model for simulating oscillatory and sliding motions of a composite caisson breakwater subject to impulsive wave loads. The CFD model was set up with the computational toolkit Proteus, which is a FEM-based software originally developed for solving generic transport equations. It has been recently used for simulating fluid–structure interaction within the context of coastal flows by using mesh deformation and immersed solid techniques. In this study, sliding and overturning of the caisson superstructure were modeled by coupling mesh deformation techniques with a dynamic model for the caisson motion response. Results were compared with experimental data and good agreement was achieved, given the uncertainties involved. These uncertainties were also assessed through a sensitivity analysis of the caisson, which demonstrated the importance of appropriate selection of numerical parameters and precise definition of the material and physical properties. Overall, the modeling approach further advances the state of the art in similar models by being capable of modeling random sea states while using a fully coupled approach for the fluid–structure interaction problem, which also allows the prediction of pore pressure buildup and uplift forces in the rubble foundation.