CFD analysis of coastal flood risk: overtopping related phenomena

Abstract

This PhD thesis aims to present the results of the validation of an innovative numerical procedure for simulating the interaction between wave motion and vertical structures. Wave overflow phenomena are the most frequent causes of risk associated with these types of structures. In fact, in many cases these structures are designed to protect roads, social activity and buildings overlooking the coast. The potential impact on coastal structure induced by climate change is the main problem of risk associated to coastal flooding induced by wave overtopping processes. The topic of the research project concerns the use of Computational Fluid Dynamics (CFD) techniques to analyse and support the design of maritime structures used for prevention and mitigation of coastal flooding risk. The aim of the research is to study the interaction between wave motion and vertical wall structures, with attention to the phenomenon of wave overtopping. Wave overtopping can be estimated by physical models, empirical methods, or numerical approach. Most empirical methods are based on physical model tests. However, there is a wide range of configurations of structures and wave conditions, and empirical methods often have their own specific conditions of applicability. It is not clear whether the extrapolation of these methods is applicable. In order to extend the applicability of empirical methods, numerical modeling can be used as a complementary tool to predict these phenomena. Numerical models can simulate the overtopping process on a prototype scale, which can avoid scale effects. In addition, you can manage complicated configurations and a wide range of wave conditions. The focus of the present work is to demonstrate the applicability of numerical CFD techniques for these types of problem by comparing it for various geometrical configurations with other numerical tools, experimental results, formulas from scientific literature and neural network tool. The objective is to reduce the gap with physical experiments and fill the gaps in the related scientific literature, using innovative numerical techniques of computational fluid dynamics. The case study analysed in this research activity concerns a vertical seawall named Malecòn Traditional (Cuba) with a significant effect of the foreshore on wave transformation and consequently on wave overtopping that was not extensively investigated in the available literature. The analysis was supported by analogous experiments developed in the hydraulics laboratory at the University of Naples, conducted jointly by Prof. Mariano Buccino and Prof. Louis Cordova with support of C.U.G.RI. [edited by Author]