Stokesian dynamics optimization of a three linked spheres micro-swimmer

I. BERDAKIN; V. I. MARCONI; ADOLFO J. BANCHIO

Villa Carlos Paz

Workshop; XIII Latin American Workshop on Nonlinear Phenomena (LAWNP 2013); 2013

FaMAF, UNC

Self-propulsion of microorganisms and articial swimmers is only possible through the generation of motility strategies that are able to overcome the absence of inertia. This condition, implied in every low Reynolds number regime, enables the success of only those strategies that are irreversible in phase space. One of the simplest swimmers meeting this requirement is the three-linked-spheres, a swimmer built upon three spheres linked by two arms that contracts asynchronously. This simple swimmer has received a lot of attention because it can be studied both, analytically and numerically. In this work we use stokesian dynamics simulations to study in detail the forces acting on each of the swimmer´s components and the power consumption during its motion. We define eficiency as the ratio between power dissipation and the work needed to produce the same motion by an external force. We nd that the most ecient swimmer is that in which its arms contracts almost absolutely. Interestingly, under these optimum conditions, the analytical predictions based on rst order approximations of the hydrodynamic equations divert signicantly from those found in our simulations, in which near eld interactions are taken into account. This highlights the importance of considering the nite size of the spheres, as it is done by the method implemented here. We believe that the results shown in this work would be very useful when designing an articial swimmer of this kind with the intention to test it experimentally.