India - Wave Energy Converters for Combined Clean Energy and Coastal Protection

Modelling tools for assessment of OWC-technology for harvest of wave energy is being developed by NTNU and SINTEF in Norway. The project includes collaboration with IIT Madras in India which performs experiments for model validation. Initially the project focused on 2D modelling, both mathamtically and experimentally to test perfomance identifying important parameters for the OWC. The results of the 2D assessments were presented at a joint workshop at IIT Madras in November 2013. Lately 3D modelling and experiement have been conducted. The modelling results are consistent with the experimental results. Thus a modelling concept for assessing OWC have been developed.

Ocean wave energy can be converted by oscillatory water column devices (OWC). By combining OWC devices together with breakwaters, the building costs and technical difficulties can be reduced significantly. In addition, such a concept has great socio econo mic benefits. In the current project combined OWC/breakwater structures will be investigated by physical and numerical models in a joint effort by the NTNU Trondheim in Norway and the IIT Madras in India. Laboratory experiments will be performed by the P hD student in India. Here parameters like different wave conditions, water depths, sea bottom topographies, OWC chamber designs and breakwater designs will be tested and analyzed. At first, a simplified two-dimensional setup will be used, assuming an infi nite width of the structure. Later, with the gained knowledge from the 2D cases, a more realistic three-dimensional experimental setup will be employed. The physical modeling part will focus on bottom fixed structures. The numerical modeling will be perf ormed by the PhD student and the researcher in Norway. The fully three-dimensional computational fluid dynamics (CFD) model REEF3D will be used, which is published under the GPL open-source licence. The model employs the level set method for the calculati on for the complex free surface and can accordingly calculate the air flow in the OWC chamber in addition the water flow. The hydrodynamics, the wave kinematics and the wave forces on the OWC/breakwaters will be investigated as well as the turbulence of t he water and air flow inside the OWC chamber. Data from the laboratory experiments will be used for validation. In addition to bottom fixed structures, the numerical model will be used to simulate floating OWC/breakwater structures. A floating body algori thm for the calculation of the six degrees of freedom motion and for the interaction between the hydrodynamics with the complex free surface will be implemented into the numerical model.