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arXiv · 2205.10288

Viscoelastic levitation

Yunxing Su·Alfonso Castillo·On Shun Pak·Lailai Zhu·Roberto Zenit
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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.

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Yunxing Su, Alfonso Castillo, On Shun Pak, Lailai Zhu, Roberto Zenit. 2022-05-20. Viscoelastic levitation. https://doi.org/10.1017/jfm.2022.418

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