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Published on: May 9, 2021
On the cross-streamline lift of microswimmers in viscoelastic flows
Akash Choudhary1, Holger Stark1
1Institute of Theoretical Physics, Technische Universität Berlin, 10623 Berlin, Germany. a.choudhary@campus.tu-berlin.de.
Abstract:
The current work studies the dynamics of a microswimmer in pressure-driven flow of a weakly viscoelastic fluid. Employing a second-order fluid model, we show that a self-propelling swimmer experiences a viscoelastic swimming lift in addition to the well-known passive lift that arises from its resistance to shear flow. Using the reciprocal theorem, we evaluate analytical expressions for the swimming lift experienced by neutral and pusher/puller-type swimmers and show that they depend on the hydrodynamic signature associated with the swimming mechanism. We find that, in comparison to passive particles, the focusing of neutral swimmers towards the centerline can be significantly accelerated, while for force-dipole swimmers no net modification in cross-streamline migration occurs.
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