Helical propulsion in shear-thinning fluids

Abstract

Swimming microorganisms often have to propel in complex, non-Newtonian fluids. We carry out experiments with self-propelling helical swimmers driven by an externally rotating magnetic field in shear-thinning, inelastic fluids. Similarly to swimming in a Newtonian fluid, we obtain for each fluid a locomotion speed which scales linearly with the rotation frequency of the swimmer, but with a prefactor which depends on the power index of the fluid. The fluid is seen to always increase the swimming speed of the helix, up to 50% faster and thus the strongest of such type reported to date. The maximum relative increase for a fluid power index of around 0.6. Using simple scalings, we argue that the speed increase is not due to the local decrease of the flow viscosity around the helical filament but hypothesise instead that it originates from confinement-like effect due to viscosity stratification around the swimmer.

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Cited by in corpus (16)

• Enhanced bacterial swimming speeds in macromolecular polymer solutions
• Enhanced rotational motion of spherical squirmer in polymer solutions
• Swimming in Complex Fluids
• Effects of shear thinning viscosity and viscoelastic stresses on flagellated bacteria motility
• Helical locomotion in granular media
• An empirical resistive-force theory for slender biological filaments in shear-thinning fluids
• Swimming efficiency in a shear-thinning fluid
• Dynamics of a helical swimmer crossing viscosity gradients
• Front-back asymmetry controls the impact of viscoelasticity on helical swimming
• Self-diffusiophoretic propulsion of a spheroidal particle in a shear-thinning fluid
• 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
• Enhancement of microorganism swimming speed in active matter
• Flagellum Pumping Efficacy in Shear-Thinning Viscoelastic Fluids
• Thrifty swimming with shear-thinning
• Helical trajectories of swimming cells with a flexible flagellar hook