Viscoelastic levitation. (25th July 2022)

• Record Type: Journal Article
• Authors: Su, Yunxing; Castillo, Alfonso; Shun Pak, On; Zhu, Lailai; Zenit, Roberto
• Is Part Of: Journal of fluid mechanics. Volume 943(2022)
• Publication Date: 2022-07-25
• Subjects: particle/fluid flow -- viscoelasticity; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2022.418
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract: 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, theoretical 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.