Dynamics of a Three-Dimensional Oscillating Foil Near the Free Surface

摘要: We investigate the free-surface effects on an underwater three-dimensional foil undergoing constant translation and periodic oscillation using a hybrid computational method. In this approach, fluid motion around is modeled via boundary-integral formulation, shed vorticity represented as shear layer originated from trailing edge, while waves are resolved by spectral algorithm. apply method to hydrodynamic forces wave signatures of two canonical problems oscillating foils with forward speed: horizontal heaving vertical in sway motion. horizontal-foil case, we find that solution has strong dependence unsteady parameter. Near critical value, mean thrust propulsive efficiency significantly reduced, field dominated produced oscillatory rather than steady Kelvin due The surface induced wake vortices appear sequence ringlike patterns along track. contrast, for swaying foil, vary smoothly near τ c , wake-induced exhibit characteristic meandering feature.