Effect of Tapering on Swimming Efficiency of Flagellated Microswimmer at Low Reynolds Number

The swimming efficiency of a microswimmer composed of a rigid spherical head fixed to an elastic filament with tapered cross section is analyzed in Stokes flow regime. The small-amplitude harmonic base-angle actuation and linear taperings are assumed. The formulation of elastohydrodynamic equations and solution procedure are adapted from the theory of swimming developed by Lauga. The numerical results on the propulsion speed and the energy efficiency of the swimmer are presented as a function of the filament length and taper ratio. The results demonstrate that by introducing a linear filament tapering both the propulsion speed and the energy efficiency can be enhanced with an appropriate trade-off with the filament length.