Inertial three-sphere swimmer

The Najafi-Golestanian microswimmer (Najafi and Golestanian, Phys. Rev. E, 69,

062901, 2004), which consists of three spheres linked by rigid rods, represents a simple,

elegant way for self-propulsion at low Reynolds numbers. In this work, we use numerical

simulations based on the immersed boundary method to go beyond the low-Reynolds-

number regime and examine the impact of fluid inertia on the propulsion characteristics

of the swimmer. Our results show that the inertial effect modifies not only the speed but

also the direction of propulsion depending on the different parameters of the system. The

findings may inform the design of artificial swimmers that operate at small but finite Reynolds numbers.