Numerical Simulation of a Cylindrical Oscillating Water Column Type Wave Energy Device

Wave energy is one of the most attractive renewable energy resources in the world. While among thousands types of wave energy devices (WEC), Oscillating Water Column stands out for its simplicity and robustness. Cylindrical OWC is an axis-symmetry device, thus its performance is independent of incident wave direction which makes it suitable to offshore applications.

This project uses Commercial Fluid Dynamic Software to simulate the hydrodynamic performance of a 3D cylindrical OWC device under wave excitation. Ocean wave forces the trapped air inside the chamber to go through a power take-off system which is simplified as an orifice plate in the present study. The induced air motion is illustrated in Figure 1. Simulation results are validated against the experiment carried out in the Kelvin Hydrodynamic Lab at the University of Strathclyde.

Scaling effect has been one of the most concerned issues in wave energy industry since most of the research and development work were carried out at model scale level to minimize the initial investment cost. However, due to the reasons that model scale experiment usually can’t represent the full scale device precisely, large scale model test is often needed. This increases the capacity and running cost dramatically. On the other hand, by using CFD method, we can simulate the full scale device with a relatively low computational cost. Therefore, the present study will utilize CFD tool to scale up the model and investigate the scale effect. Modelling result will be further validated with experiment which is to be done in the near future.

Figure 1. Air velocity inside the OWC device.

For more information about the project contact Dr Qing Xiao (qing.xiao@strath.ac.uk), Senior Lecturer at the Department of Naval Architecture and Marine Engineering at the University of Strathclyde.
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Relevant publications:
Saishuai Dai, Sandy Day and Qing Xiao, An Experimental and Analytical Investigation on the Hydrodynamic Efficiency of a Cylindrical Oscillating Water Column Wave Energy Device, International Conference on Marine Technology, July, 2014, Glasgow, UK.