Actuated rheology of magnetic micro-swimmers suspensions : emergence of motor and brake states
arXiv:1710.01954 · doi:10.1103/PhysRevFluids.3.033302
Abstract
We study the effect of magnetic field on the rheology of magnetic micro-swimmers suspensions. We use a model of a dilute suspension under simple shear and subjected to a constant magnetic field. Particle shear stress is obtained for both pusher and puller types of micro-swimmers. In the limit of low shear rate, the rheology exhibits a constant shear stress, called actuated stress, which only depends on the swimming activity of the particles. This stress is induced by the magnetic field and can be positive (brake state) or negative (motor state). In the limit of low magnetic fields, a scaling relation of the motor-brake effect is derived as a function of the dimensionless parameters of the model. In this case, the shear stress is an affine function of the shear rate. The possibilities offered by such an active system to control the rheological response of a uid are finally discussed.
arXiv comment10 pages, 6 figures, accepted in PRFluids
References in corpus (12)
- The hydrodynamics of swimming microorganisms
- Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering
- A bacterial ratchet motor
- Rheology of Active-Particle Suspensions
- Turning bacteria suspensions into a "superfluid"
- Effective viscosity of microswimmer suspensions
- Enhanced diffusion due to active swimmers at a solid surface
- Non-Newtonian viscosity of E-coli suspensions
- Shearing active gels close to the isotropic-nematic transition
- Sheared active fluids: thickening, thinning and vanishing viscosity
- Destabilization of a flow focused suspension of magnetotactic bacteria
- Switching of swimming modes in Magnetospirillium gryphiswaldense
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- Magnetic microswimmers exhibit Bose-Einstein-like condensation
- Controlling stability and transport of magnetic microswimmers by an external field
- Chirotactic response of microswimmers in fluids with odd viscosity
- Emergent pattern formation of active magnetic suspensions in an external field