Montino Alessandro, DeSimone Antonio
GSSI - Gran Sasso Science Institute, viale Francesco Crispi 7, 67100, L'Aquila, Italy.
Eur Phys J E Soft Matter. 2015 May;38(5):127. doi: 10.1140/epje/i2015-15042-3. Epub 2015 May 22.
One of the simplest model swimmers at low Reynolds number is the three-sphere swimmer by Najafi and Golestanian. It consists of three spheres connected by two rods which change their lengths periodically in non-reciprocal fashion. Here we investigate a variant of this model in which one rod is periodically actuated while the other is replaced by an elastic spring. We show that the competition between the elastic restoring force and the hydrodynamic drag produces a delay in the response of the passive elastic arm with respect to the active one. This leads to non-reciprocal shape changes and self-propulsion. After formulating the equations of motion, we study their solutions qualitatively and numerically. The leading-order term of the solution is computed analytically. We then address questions of optimization with respect to both actuation frequency and swimmer's geometry. Our results can provide valuable conceptual guidance in the engineering of robotic microswimmers.
低雷诺数下最简单的模型游泳者之一是纳贾菲和戈莱斯坦尼安提出的三球体游泳者。它由三个通过两根杆连接的球体组成，这两根杆以非互易方式周期性地改变它们的长度。在这里，我们研究了该模型的一个变体，其中一根杆被周期性驱动，而另一根杆被一个弹性弹簧取代。我们表明，弹性恢复力和流体动力阻力之间的竞争导致被动弹性臂相对于主动臂的响应出现延迟。这导致了非互易的形状变化和自我推进。在建立运动方程后，我们对其解进行了定性和数值研究。解析计算了解的主导项。然后，我们讨论了关于驱动频率和游泳者几何形状的优化问题。我们的结果可以为机器人微游泳者的工程设计提供有价值的概念指导。
