Viscoelastic levitation
arXiv:2205.10288 · doi:10.1017/jfm.2022.418
Abstract
The effects of viscoelasticity have been shown to manifest themselves via symmetry breaking. In this investigation, we show a novel phenomenon that arises from this idea. We observe that when a dense sphere is rotated near a wall (the rotation being aligned with the wall-normal direction and gravity), it levitates to a fixed distance away from the wall. Since the shear is larger in the gap (between the sphere and the wall) than in the open side of the sphere, the shear-induced elastic stresses are thus asymmetric, resulting in a net elastic vertical force that balances the weight of the sphere. We conduct experiments, theoretic models, and numerical simulations for rotating spheres of various sizes and densities in a Boger-type fluid. In the small Deborah number range, the results are collapsed into a universal trend by considering a dimensionless group of the ratio of elastic to gravitational forces.
References in corpus (17)
- The hydrodynamics of swimming microorganisms
- Confinement Stabilizes a Bacterial Suspension into a Spiral Vortex
- Ferromagnetic and antiferromagnetic order in bacterial vortex lattices
- Self-propulsion in viscoelastic fluids: pushers vs. pullers
- Spontaneous Circulation of Confined Active Suspensions
- Squirming through shear-thinning fluids
- Fluid elasticity increases the locomotion of flexible swimmers
- Fluid Elasticity Can Enable Propulsion at Low Reynolds Number
- Flapping motion and force generation in a viscoelastic fluid
- Locomotion in complex fluids: Integral theorems
- Active matter logic for autonomous microfluidics
- Pumping by flapping in a viscoelastic fluid
- Swimming trajectories of a three-sphere microswimmer near a wall
- Force moments of an active particle in a complex fluid
- Viscoelastic propulsion of a rotating dumbbell
- Front-back asymmetry controls the impact of viscoelasticity on helical swimming
- Micropropulsion and microrheology in complex fluids via symmetry breaking