Numerical Simulation of Nonlinear Waves in Numerical Wave Tank Using Boundary Element Method

Abstract

Increasing world population and consequent increase in fossil fuel consumption emerge the necessity of looking for new sources of energy, resources that are clean, cheap, and renewable. The extracted energy from the sea is one of the alternatives of fossil fuels. This energy is available either in the form of tidal or wave energy. Wave energy converters are devices which convert the permanent sea waves to electrical energy. In order to achieve this technology and according to the terms of the sea conditions, developing the numerical modeling in a numerical wave tank is very important for modeling the system and analyzing its performance in different circumstances. So the sea conditions can be applied to this system. Simulation of linear and nonlinear waves in numerical wave tank has been one of the most important topics of interest to researchers and scholars working in the areas of the marine industries. Extensive numerical studies have been conducted using different methods in the past years. Among them, boundary element method is one of the most useful methods for modeling the boundary value problems, particularly for problems related to the hydrodynamic of marine structures. It is evident from literature that this method is very efficient and produces very accurate results for problems considered in this field. In this paper, due to capabilities of the boundary element method and using the Euler-Lagrangian method, nonlinear waves generated by a piston wave maker in a two-dimensional wave tank are investigated. For time evolving of wave in the simulation and solving the freesurface boundary condition equations, the conventional Euler-Lagrangian method is used too. For evaluation of results, a sample wave is chosen for simulation, and its result is compared with a result of an analytical method. Finally, a wave with characterization of average Caspian Sea waves is selected for simulation. The simulations have shown that if the wave maker oscillates with the average wave height and period of the Caspian Sea waves, what will be the characteristics of the generated waves, then the extractable energy potential is obtained from it.