Abstract
The water particles are known to undergo orbital motion in wave motion. This orbital motion was studied and seven Savonius rotors with same diameters but different blade angles were constructed and tested in a wave channel to find the optimum blade angle.Experiments were carried out in a two-dimensional wave channel that generates sinusoidal waves. The submergence of the rotors below the mean water level was varied. The optimum blade curvature was found to be 70o from the rpm measurements. Two arrays of rotors with this blade curvature were then employed at different depths to study the energy extraction from the orbital motion.The flow around the rotors was documented with particle image velocimetry (PIV) measurements. It was found that the optimum performance of the rotors is obtained at the minimum spacing between the rotors. Experiments carried out with two arrays showed that the maximum energy extraction from the orbiting particles takes place when the gap between the upper and lower arrays is less. This concept can be extended to multiple arrays with reducing rotor diameters at deeper submergences and power can be generated from the ocean waves with a 'Wave Farm'

Brief Resume
Dr. M. R. Ahmed is an Associate Professor of Mechanical Engineering at the University of the South Pacific (USP) at its Laucala Campus in Fiji Islands. He is a co-leader of the Renewable Energy Research Group at USP. He served as the Head of the Division of Mechanical Engineering at USP from 2006 to 2010. He holds a PhD degree from IIT Bombay that he earned in 1998. His areas of interest are thermo-fluids and energy engineering. He is working in these areas for well over a decade and has published more than 60 papers in international journals and conference proceedings. He was an invited speaker at RE2008 Conference held in Busan, a member of the International Advisory Boards of the 2nd International Symposium on Low Carbon and Renewable Energy Technology, ISLCT2010 held in Jeju Island, Korea, in November 2010 and of the Asia-Pacific Forum on Renewable Energy that will be held in November 2011 in Korea. He is a reviewer for many international journals. He was also a reviewer of the IPCC report on Renewable Energy Sources and Climate Change Mitigation, published recently. He is working on a number of projects in the areas of ocean and wind energies and has given invited lectures at a number of universities and research centres. He is a member of the American Society of Mechanical Engineers, a Senior Member of the American Institute of Aeronautics and Astronautics and a member of the World Renewable Energy Network.