Sea lions swim using primarily their foreflippers, which is uncommon among aquatic mammals. While a significant body of literature exists which investigates the hydrodynamics of body-caudal swimming, relatively little research has looked at sea lion propulsion. In this work, particle imaging velocimetry is used to observe the flow around a robotic model sea lion flipper. The model flipper was cast in silicone from a high-resolution scan of a sample sea lion foreflipper. The model flipper was actuated at the root, and its motion was controlled by a programmable servomotor. It was observed that the thrust-producing clapping motion of the flipper entrained significant fluid momentum on the suction side of the flipper, which developed into a shed vortex and contributed to downstream momentum (and therefore thrust). Rotating the robotic flipper more quickly produced greater downstream jet velocities, but at a lower conversion of rotational velocity, suggesting that this mechanism of propulsion can be optimized based on the system needs.

中文翻译：

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机器人海狮前叉从静止开始产生的流场。

海狮主要使用其前脚蹼游泳，这在水生哺乳动物中并不常见。尽管存在大量研究体尾游泳水动力的文献，但相对较少的研究着眼于海狮推进。在这项工作中，粒子成像测速仪用于观察机器人模型海狮鳍状肢周围的流动。通过对海狮前叉样品的高分辨率扫描，将模型的脚蹼铸入硅树脂中。型号脚蹼在根部被致动，其运动由可编程伺服电机控制。观察到，鳍状件产生推力的拍击运动在鳍状件的吸入侧夹带了显着的流体动量，该流体动量发展成脱落的涡流并有助于下游动量（并因此而产生推力）。