Numerical Study of Penguin Wing Propulsion Using Immersed Boundary Method
Please login to view abstract download link
Leading edge sweep angle is a key geometric feature observed in biological structures, such as fish tails, mammal flukes, aquatic-animal flippers, and bird or insect wings. In the study of constant aspect ratio foils undergoing tail-like and flipper-like kinematics, the correlation between the sweep angle and the propulsive force and power for both taillike and flipper-like motions is negligible [1]. Simulating gliding penguin flippers suggests that sweepback effectively prevents abrupt wing stalls, with the optimal sweepback angle dependent on swimming speed [2]. In a recent experimental study on penguin wings, Shen [3] also found that hydrodynamic effciency is not significantly affected by sweep angle. However, when the motion parameters are the same, a smaller sweep angle results in larger propulsion force. Due to the diffculty of equipment manufacturing, the feathering axis in experimental research can only be set perpendicular to the flapping axis, which is different from the actual motion of penguin wings. Therefore, this work offers a detailed analysis of the hydrodynamics of a penguin wing with different feathering axes, e.g. fixed and local, and predefined sweep angles in forward propulsion. The computational fluid dynamics (CFD) solver based on direct numerical simulation (DNS) and immersion boundary method (IBM) calculates the fluidic properties and visualizes the flow structure around the wing.
