On the Squeeze Film Levitation Phenomenon in Incompressible Liquid Environments

Transverse vibrations can levitate objects in air, via the squeeze-film effect. The underlying physics of this phenomenon is attributed to the non-linear compressibility of the viscous air film, well captured by the Reynolds lubrication theory. A similar levitation has been demonstrated in liquids, however, the working mechanism of the levitation in the incompressible liquid case is unclear, with the existing theories contradicting documented experimental evidence. In this study, we conduct a time-average analysis on the coupled dynamics of the levitated object and the liquid film. Our analysis reveals that in-liquid levitation is driven by inertial forces, with the liquid’s convective inertia playing a major role in generating steady-state levitation. We derive the physical law governing in-liquid levitation in the special case of prevailing convection effects, confirmed experimentally. We also conducted a comparative experiment showing the load-carrying capacity of the in-liquid system to be up to ten times greater than its air counterpart. By uncovering key fundamental insights, this work could potentially lead to the informed design of new in-liquid levitation systems for non-contact manipulation and friction modulation in the medical domain.