Ship hull wake effect on the hydrodynamic performance of a heave–pitch combined oscillating fin

The hydrodynamic analysis of flapping foil inspired by the thunniform fish propulsion is carried out numerically. The hydrodynamic performances of 2D and 3D rigid oscillating foils are analysed for a range of Strouhal numbers (St). The performance parameters such as thrust coefficient, power coefficient and hydrodynamic efficiency are obtained in both open water and behind ship conditions, where the wake effect of the ship influences the hydrodynamic performance parameters of the foil. Thrust and efficiency variations with Strouhal number are estimated and it is found that the efficiency reaches maximum at St = 0.3.