Undulatory swimming in non-Newtonian fluids

Abstract

We numerically investigate the effects of non-Newtonian fluid properties, including shear thinning and elasticity, on the locomotion of Taylor’s swimming sheet with arbitrary amplitude. Our results show that elasticity hinders the swimming speed, but a shear-thinning viscosity in the absence of elasticity enhances the speed. The combination of the two effects, modelled using a Giesekus constitutive equation, hinders the swimming speed. We find that the swimming speed of an infinitely long waving sheet in an inelastic shear-thinning fluid has a maximum, whose value depends on the sheet undulation amplitude and the fluid rheological properties. The power consumption, on the other hand, follows a universal scaling law.