It is interesting to note that design approach for an oscillating water turbine is based on biomimicry,
where the energy harvesting by fish-like motion is adopted for the device design. Fish commonly live in
high-energy environments such as rivers and streams. They usually encounter vortices which are
generated from fluid flow past stationary objects or by the propulsive movement of other fish. It seems
reasonable that fish may harvest the energy from vortices to reduce its muscle activity [3]. Sketched
configuration of an oscillating water turbine is shown in Fig.1 (a). The device is based on using an
oscillating turbine to extract energy from vortices which are produced from an upstream cylinder. In order
to find out the parameters which affect mechanical power and efficiency, the parameters, namely, flow
velocity U, diameter of cylinder D, longitudinal distance between cylinder and turbine S, transverse
distance between cylinder and turbine L, friction torque T and spring stiffness k are determined. The
specifications of parameters are listed in Table 1.