Floppy swimming: Viscous locomotion of actuated elastica
Floppy swimming: Viscous locomotion of actuated elastica
复制标题
DOI：
10.1103/physreve.75.041916
复制
发表时间：
2007-04-01
影响因子：
2.4
通讯作者：
Lauga, Eric
中科院分区：
文献类型：
--
作者：
Lauga, Eric
周期性地驱动粘性液体中的弹性细丝通常会打破珀塞尔扇形定理的约束，从而产生净推进力。这一观察结果提出了一种设计简单的游泳装置的方法，我们称之为“弹性游泳者”，其中致动机构嵌入固体中，所得的游泳者可以自由移动。本文对弹性游泳运动学进行了理论研究。在讨论了这一现象的基本物理图象和期望的标度关系后，我们解析地导出了小激励振幅极限下的弹性游动速度。重点是两个未知数之间的耦合问题，即形状的弹性长丝和游泳运动学，必须同时解决。然后，我们计算所得的游泳设备的性能及其对几何形状的依赖。最佳的驱动频率和身体的形状，推导出的灯丝形状和内部扭矩的讨论。游泳使用多个弹性细丝进行了讨论，并提出了简单的策略，导致直线游泳轨迹。最后，我们比较了弹性游泳和游泳微生物的性能。
Actuating periodically an elastic filament in a viscous liquid generally breaks the constraints of Purcell's scallop theorem, resulting in the generation of a net propulsive force. This observation suggests a method to design simple swimming devices-which we call "elastic swimmers"-where the actuation mechanism is embedded in a solid body and the resulting swimmer is free to move. In this paper, we study theoretically the kinematics of elastic swimming. After discussing the basic physical picture of the phenomenon and the expected scaling relationships, we derive analytically the elastic swimming velocities in the limit of small actuation amplitude. The emphasis is on the coupling between the two unknowns of the problems-namely the shape of the elastic filament and the swimming kinematics-which have to be solved simultaneously. We then compute the performance of the resulting swimming device and its dependence on geometry. The optimal actuation frequency and body shapes are derived and a discussion of filament shapes and internal torques is presented. Swimming using multiple elastic filaments is discussed, and simple strategies are presented which result in straight swimming trajectories. Finally, we compare the performance of elastic swimming with that of swimming micro-organisms.