The role of body flexibility in stroke enhancements for finite-length undulatory swimmers in viscoelastic fluids

Abstract

The role of passive body dynamics on the kinematics of swimming micro-organisms in complex fluids is investigated. Asymptotic analysis of small amplitude motions of a finite-length undulatory swimmer in a Stokes-Oldroyd-B fluid is used to predict shape changes that result as body elasticity and fluid elasticity are varied. Results from the analysis are compared with numerical simulations, and the small amplitude analysis of shape changes is quantitatively accurate at both small and large amplitudes, even for strongly elastic flows. We compute a stroke-induced swimming speed that accounts for the shape changes, but not additional effects of fluid elasticity. Elastic induced shape changes lead to larger amplitude strokes for sufficiently soft swimmers in a viscoelastic fluid, and these stroke boosts can lead to swimming speed-ups, but we find that additional effects of fluid elasticity generically slow down swimmers. High amplitude strokes in strongly elastic flows lead to a qualitatively different regime in which highly concentrated elastic stresses accumulate near swimmer bodies and where dramatic slow-downs are seen.

References in corpus (11)

• The hydrodynamics of swimming microorganisms
• Propulsion in a viscoelastic fluid
• Swimming speeds of filaments in nonlinearly viscoelastic fluids
• Theory of swimming filaments in viscoelastic media
• Floppy swimming: Viscous locomotion of actuated elastica
• Flagellar Kinematics and Swimming of Algal Cells in Viscoelastic Fluids
• Fluid elasticity increases the locomotion of flexible swimmers
• Beating patterns of filaments in viscoelastic fluids
• Enhanced active swimming in viscoelastic fluids
• Undulatory swimming in shear-thinning fluids: Experiments with C. elegans
• The effect of gait on swimming in viscoelastic fluids

Cited by in corpus (5)

• Orientation dependent elastic stress concentration at tips of slender objects translating in viscoelastic fluids
• Polymer stress growth in viscoelastic fluids in oscillating extensional flows with applications to micro-organism locomotion
• Well-posedness and applications of classical elastohydrodynamics for a swimming filament
• Flagellum Pumping Efficacy in Shear-Thinning Viscoelastic Fluids
• Microswimming in viscoelastic fluids