Biofluiddynamic Study on Effectivity of Artificial Tail Flukes of Dolphin

点击翻译按钮获取中文摘要

Dolphins swim fast and jump high. It is significant to clarify its biokinematic performance and propulsive performance from the bioengineering viewpoint. We know that the tail flukes play an important role in generating efficient propulsive force. However, it is difficult to measure the propulsive force of swimming dolphin directly. James Gray pointed out the problem that the dolphin can swim faster than at the speed estimated by the hydrodynamic drag acting its body and the power of its muscles. This is well known as Gray's paradox. As for the propulsive force, we paid attention to the structure of the tail fin and its deformation behavior by the fin oscillation. We thought the estimation of propulsive force by obtaining the relationship between the hydrodynamic force acting on the fin and the deformation of the fin.A dolphin kept in Okinawa Churaumi aquarium in Japan suffered progressive necrosis in both tail flukes and lost about 75 % of the flukes by surgical treatment. Then prosthetic flukes for the dolphin were designed in order to assist the dolphin to swim as before. The mechanical properties on the artificial tail fin and a tail flukes of dolphin were investigated. An artificial tail wing modeled on the dolphin's tail flukes was made and the propulsive performance was investigated. The dolphin-like wing almost generated positive propulsive force in one oscillating cycle and its fluctuations were small. We were convinced that the artificial tail fin was useful as the propulsor of underwater vehicles. The measurement of the behavior of the dolphin-like wing using acceleration sensor set inside the wing will be carried out at the next stage.