Meeting Abstract
Penguins are wing-propelled diving birds capable of maneuvers such as rapid turns or accelerations. Previous bio-logging studies and 2-D motion analysis studies have revealed the basic swimming characteristics such as average swimming speed, dive depth, or wingbeat frequency. However, the details of the 3-D wing and body kinematics are largely unknown, which will be the foundation of understanding the hydrodynamic force generation mechanism by the penguin wings (flippers). To obtain the 3-D kinematics, we recorded a swimming penguin in a large water tank at an aquarium using multiple waterproof video cameras at 60 frames per second. Based on the 3-D coordinates of the characteristic points on the penguins, the wing kinematics such as stroke angle, sweepback angle, feathering angle and angle of attack were calculated. The wing kinematics were used to obtain instantaneous fluid dynamic forces with the quasi-steady blade element method. The resultant forces were compared with the fluid dynamic forces obtained from the inverse dynamics by using the buoyancy force estimated from a simplified 3-D body model. We found that during turning maneuvers at slow speed, the angle of attack of the inner wing was notably large up to around 40° while the angle of attack of the outer wing was moderate, 25° or less. On the other hand, such drastic increase in angle of attack was not observed during slow forward swimmings. This suggests that the penguin could be able to largely change the fluid dynamic force of its wings for maneuvering due to wide operational range of angle of attack.
