Fluid elasticity increases the locomotion of flexible swimmers

Abstract

We conduct experiments with flexible swimmers to address the impact of fluid viscoelasticity on their locomotion. The swimmers are composed of a magnetic head actuated in rotation by a frequency-controlled magnetic field and a flexible tail whose deformation leads to forward propulsion. We consider both viscous Newtonian and glucose-based Boger fluids with similar viscosities. We find that the elasticity of the fluid systematically enhances the locomotion speed of the swimmer, and that this enhancement increases with Deborah number. Using Particle Image Velocimetry to visualize the flow field, we find a significant difference in the amount of shear between the rear and leading parts of the swimmer head. We conjecture that viscoelastic normal stresses lead to a net elastic forces in the swimming direction and thus a faster swimming speed.

14 pages, 7 figures, 3 videos

References in corpus (8)

• The hydrodynamics of swimming microorganisms
• Propulsion in a viscoelastic fluid
• Experimental Investigations of Elastic Tail Propulsion at Low Reynolds Number
• 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
• Life at high Deborah number

Cited by in corpus (13)

• Fluid elasticity increases the locomotion of flexible swimmers
• Enhanced active swimming in viscoelastic fluids
• Locomotion in complex fluids: Integral theorems
• Helical propulsion in shear-thinning fluids
• The mechanism of propulsion of a model microswimmer in a viscoelastic fluid next to a solid boundary
• Hydrodynamic interaction of a bubble pair in viscoelastic shear-thinning fluids
• Maximizing propulsive thrust of a driven filament at low Reynolds number via variable flexibility
• Formation of a strong negative wake behind a helical swimmer in a viscoelastic fluid
• Force and torque-free helical tail robot to study low Reynolds number microorganism swimming
• Viscous pumping inspired by flexible propulsion
• Viscoelastic levitation
• A swimming bacterium in a two-fluid model of a polymer solution
• Microswimming in viscoelastic fluids