Transit of an Erythrocyte-Inspired Swimmer Through a Pore

Abstract By using a fluid-structure interaction model, the dynamics of a swimming machine inspired by the tank-treading behavior of erythrocytes (red blood cells) during its transit through a pore in a wall are numerical investigated. Unlike traditional locomotion methods in aquatic environments, which rely mostly on hydrodynamic pressure for propulsion, this design utilizes fluid shear stress on its surface enabled through circulatory motion of its membrane to generate thrust force. The numerical results show that this novel method has unique advantage in negotiating obstacles such as pores when swimming at relatively low Reynolds numbers (O(10) or less). Specifically, when the swimmer passes through a pore, it is accelerated by the interaction between its membrane and the solid boundary despite the fact that the drag force is significantly increased during this process. Meanwhile, although the instantaneous power expenditure is increased, due to the reduced transit time the total energy consumption during the transit is reduced, leading to lower cost of transport. These characteristics suggest that this bio-inspired locomotion method has great potential in applications where it is necessary to swim through confined space with obstacles at low Reynolds number.