Enhanced active swimming in viscoelastic fluids

Abstract

Swimming microorganisms often self propel in fluids with complex rheology. While past theoretical work indicates that fluid viscoelasticity should hinder their locomotion, recent experiments on waving swimmers suggest a possible non-Newtonian enhancement of locomotion. We suggest a physical mechanism, based on fluid-structure interaction, leading to swimming in a viscoelastic fluid at a higher speed than in a Newtonian one. Using Taylor's two-dimensional swimming sheet model, we solve for the shape of an active swimmer as a balance between the external fluid stresses, the internal driving moments, and the passive elastic resistance. We show that this dynamic balance leads to a generic transition from hindered rigid swimming to enhanced flexible locomotion. The results are physically interpreted as due to a viscoelastic suction increasing the swimming amplitude in a non-Newtonian fluid and overcoming viscoelastic damping.

7 pages, 3 figures

References in corpus (6)

• Propulsion in a viscoelastic fluid
• Swimming speeds of filaments in nonlinearly viscoelastic fluids
• Theory of swimming filaments in viscoelastic media
• Fluid elasticity increases the locomotion of flexible swimmers
• Beating patterns of filaments in viscoelastic fluids
• Fluid transport by active elastic membranes

Cited by in corpus (8)

• Physics of Microswimmers - Single Particle Motion and Collective Behavior
• Helical propulsion in shear-thinning fluids
• The mechanism of propulsion of a model microswimmer in a viscoelastic fluid next to a solid boundary
• Maximizing propulsive thrust of a driven filament at low Reynolds number via variable flexibility
• Viscous propulsion in active transversely-isotropic media
• Biopolymer dynamics driven by helical flagella
• Polymer stress growth in viscoelastic fluids in oscillating extensional flows with applications to micro-organism locomotion
• Microswimming in viscoelastic fluids