Numerical study of a fixed oscillating water column

Renewable energy sources are critical in accelerating the global transition to sustainable energy systems. Ocean waves carry high energy density compared to other renewable energy sources. The Oscillating Water Column (OWC) is the most promising type from all the devices that convert wave energy into electricity. The first step in designing OWC is performing a numerical model and WEC-Sim is a robust and powerful tool in the wave energy industry, especially for heaving devices. However, Modelling OWC with WEC-Sim requires some alterations to the program. This study reports an improved method for simulating fixed OWC when using WEC-Sim, by integrating a toolbox. A case study of the Mutriku OWC was performed to verify the toolbox.

This study is divided into two parts. First, a new toolbox for WEC-Sim was created, taking into account the thermodynamics of an OWC's pneumatic chamber described by the piston model. Then, some parameters of WEC-Sim were fine-tuned to adjust the toolbox, matching the results against reference results. The reference results were obtained by developing an in-house code with the frequency domain solution.

Secondly, as the toolbox was already verified, a numerical study was performed as an illustrative example of how the new toolbox can simulate a fixed OWC with different scenarios such as free decay tests, air compressibility, performance of different types of turbines, integration of valves, and control strategies.