Effect of fluid viscoelasticity, shear stress, and interface tension on the lift force in lubricated contacts

Shiyuan Hu; Fanlong Meng; Masao Doi

doi:10.1063/5.0173142

Effect of fluid viscoelasticity, shear stress, and interface tension on the lift force in lubricated contacts

J Chem Phys. 2023 Oct 28;159(16):164106. doi: 10.1063/5.0173142.

Authors

Shiyuan Hu¹, Fanlong Meng^{1

2

3}, Masao Doi^{3

4}

Affiliations

¹ CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China.
² School of Physical Sciences, University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
³ Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China.
⁴ Oujiang Laboratory, Wenzhou, Zhejiang 325000, People's Republic of China.

PMID: 37873958
DOI: 10.1063/5.0173142

Abstract

We consider a cylinder immersed in viscous fluid moving near a flat substrate covered by an incompressible viscoelastic fluid layer, and study the effect of the fluid viscoelasticity on the lift force exerted on the cylinder. The lift force is zero when the viscoelastic layer is not deformed, but becomes non-zero when it is deformed. We calculate the lift force by considering both the tangential stress and the normal stress applied at the surface of the viscoelastic layer. Our analysis indicates that as the layer changes from the elastic limit to the viscous limit, the lift force decreases with the decrease of the Deborah number (De). For small De, the effect of the layer elasticity is taken over by the surface tension and the lift force can become negative. We also show that the tangential stress and the interface slip velocity (the surface velocity relative to the substrate), which have been ignored in the previous analysis, give important contributions to the lift force. Especially for thin elastic layers, they give dominant contributions to the lift force.