Enhancement of propulsive performance of flapping foil by fish-like motion pattern

In this study, the flapping foil propulsion with a novel motion pattern is numerically investigated. The proposed motion pattern is inspired from kinematics of fish species, such as marine mammals, utilizing a foil-shaped tail to swim in aquatic environments. This motion pattern is named as fish-like flapping foil and causes the swimming kinematics to be more complex. The numerical simulation for a two dimensional NACA 0012 is conducted using computational fluid dynamics (CFD) approaches at relatively low Reynolds number of 4 × 104. The results show that proposed motion pattern would change the angle of attack profile notably. It is found that the motion trajectory as well as angle of attack profile affect the flow structure around the foil and increase the hydrodynamic loads. In this kinematic model the vortex strength and pattern of vortex evolution might change. It is observed that the proposed model for flapping foil could significantly enhance the propulsive efficiency in certain conditions (as considered in this paper), which makes it possible to apply this kind of model in order to improve propulsion performance of devices in aquatic environments.