Numerical simulation of linear water waves and wave–structure interaction

One of the main stages in the design of wave energy converters (WEC's) is the numerical modelling of a given converter. In this paper, the numerical simulation of both linear deep water waves and linear waves for the finite depth case are explored using computational fluid dynamics (CFD), to aid in this design stage. The CFD software package described in this paper is the commercial finite volume package ANSYS CFX (Release 12.1). The results of parametric studies, which were performed in order to optimise the CFD model, are detailed and a guide to creating a model that produces the desired waves is presented. The model was validated in two ways: (a) the wave created was compared to wavemaker theory (WMT) and (b) the water particle velocity and elevation of the wave was compared to linear, Airy, wave theory (LWT) for deep water waves. It was also found that wave generation in ANSYS CFX using a flap-type wavemaker was restricted to a low normalised wavenumber, k0h. In order to increase this restriction, the hinge of the wavemaker was raised and, with this alteration, it is possible to generate deep water linear waves. A case study of a real world application of wave–structure interaction, employing this methodology, is also explored.

► A methodology to generating linear waves in a numerical wave tank is described.
► An optimised model, depending on the period of the desired waves, is presented.
► The model was validated by comparing to wavemaker theory and Airy wave theory.
► Wavemaker theory is expanded to allow for a flap, which is not hinged at the base.
► The wave–structure interaction on a floating cylinder is modelled.