Viscoelastic levitation
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.
Cite
@article{arxiv.2205.10288,
title = {Viscoelastic levitation},
author = {Yunxing Su and Alfonso Castillo and On Shun Pak and Lailai Zhu and Roberto Zenit},
journal= {arXiv preprint arXiv:2205.10288},
year = {2022}
}