ABSTRACT
To understand energy absorption from ocean waves, it is necessary to understand the source itself – the fluid and the water waves – and the interactions between the fluid and the wave energy converters. In this chapter, descriptions and properties of ocean waves will be derived and discussed, based on fundamental as well as stochastic principles.
The governing equations for ocean waves are the nonlinear Navier-Stokes equations, for which analytical solutions have yet to be found. The problem must be approached approximately, and the most common approach in wave energy applications is to assume potential flow theory using assumptions such as neglecting viscosity and turbulence. The simplified equations can then be solved by analytical or numerical methods, such as the boundary element method. Another approach is to solve the full Navier-Stokes equations by numerical computation fluid dynamics simulations. To validate the numerical simulations and to capture the physical effects accurately, numerical solvers need to be complemented by physical experiments. Wave tank experiments carried out at model scales are indispensable in wave energy technology development. The numerical and experimental modelling approaches, and their differences and validity, are reviewed and discussed in the chapter.
