Computational study of oscillating hydrofoil with different plunging/pitching frequency

A numerical investigation of an oscillating hydrofoil with unequal plunging/pitching frequency is conducted by solving unsteady Navier-Stokes equations. Studies are performed for the impact of different frequency ratio on the wake structure and propulsion parameters over a wide range of plunging amplitude, pitching amplitude and oscillating reduced frequency. Results show that, for pitching oscillates at twice frequency as plunging, there exists a critical St, less than which the thrust coefficient (Ct) is larger than that of equal plunging/pitching oscillation. However, beyond this St, a reduced Ct is obtained compared to equal frequency. The lift induced by unequal oscillating and power consumption are always larger than that of equal motion.