Experimental and numerical modelling of break water overtopping for plain, converging and stairs slope

Abstract

In recent years, emphasis has been given on converting wave energies in a stable form to protect coastal areas from erosion. Wave energy has grown to develop the reputation of being a major and promising energy resource which has great potential of being the subject of much research. Wave energy converters have been studied for converting wave energies to stable and useful forms of energy. Numerical wave tanks have performed a remarkable role as a numerical tool for wave converters. The objective of this study is to employ wave tanks both experimentally and numerically. To compound to that, the main aim of this article is to present the characteristics of different types of wave overtopping structures on overtopping discharge. The numerical models have been presented using 3D Navier Stokes solver. Furthermore, Volume of fluid (VOF) method and RANS approach with k-ϵ model has been implemented for treating air- water interfaces and turbulence, respectively. Physical wave tanks with overtopping structures have been physically modelled with experiments carried out for different overtopping structures and the results obtained are then compared. Three different overtopping structure configurations have been studied namely Plain slope, Converging slope and Stairs slope. The overtopping structures have been constructed and the same dimensions used for numerical models. The experimental model has been validated against the numerical one and the accuracy has been verified and they are found to be in reasonable agreement. By generating mesh blocks of different cell numbers, grid independency study was implemented to resolve the perfect mesh size that provides a balance between accuracy and computational time to be used for rest of the simulations. Finally, the performance of the overtopping structures has been carried out for different frequencies and water levels. Accordingly, the obtained results and comparisons are demonstrated in this paper.