Resistive thrust production can be as crucial as added mass mechanisms for inertial undulatory swimmers

摘要

In this paper, we address a crucial point regarding the description ofmoderate to high Reynolds numbers aquatic swimmers. For decades, swimminganimals have been classified in two different families of propulsive mechanismsbased on the Reynolds number: the "resistive" swimmers, using local friction toproduce the necessary thrust force for locomotion at low Reynolds number andthe "reactive" swimmers, lying in the high Reynolds range, and using added massacceleration (described by perfect fluid theory). However, inertial swimmersare also systems that dissipate energy, due to their finite size, thereforeinvolving strong resistive contributions, even for high Reynolds numbers. Usinga complete model for the hydrodynamic forces, involving both reactive andresistive contributions, we revisit here the physical mechanisms responsiblefor the thrust production of such swimmers. We show, for instance, that theresistive part of the force balance is as crucial as added mass effects in themodeling of the thrust force, especially for elongated species. The conclusionsbrought by this work may have significant contributions to the understanding ofcomplex swimming mechanisms, especially for the future design of artificialswimmers.