Viscoacoustic analyses of squeeze-film levitation
A typical squeeze-film levitation system involves two rigid objects whose parallel surfaces are separated by a thin film of air. One of the objects performs high-frequency time-harmonic oscillations along an axis perpendicular to the surfaces, inducing oscillatory motion in the slender film and its immediate outer periphery. The resulting pressure variation at a given point, harmonic at leading order, exhibits a time- averaged value that differs from the ambient value, yielding a time-averaged normal force on the objects–the steady squeeze-film force (SSF)–which is typically repulsive. This phenomenon, first implemented within the context of gaseous lubrication, has been applied in recent decades to the design of non-contact levitation systems that can suspend and transport objects of interest in practical applications pertaining to material processing equipment, wall-climbing robots, and pick-and-place machinery. Further development of these new systems to address applications requiring different sizes, materials and operating conditions is limited by lack of understanding of the viscoacoustic oscillatory flow. Our recent work is intended to provide the needed understanding.
Schematic of an axisymmetric squeeze-film levitation system involving an oscillating disk. Shaded below it are waveforms that represent (b) rigid-body and(c)–(e) resonant flexural oscillations of a disk .
The variation with the air-film thickness of the steady squeeze-film force (SSF) for a disk of radius a = 7 cm oscillating with central amplitude εho = 10 μm.
The variation with the air-film thickness of the steady squeeze-film force (SSF) for a disk of radius a = 7 cm oscillating with central amplitude εho = 10 μm.
Related publications
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- Viscoacoustic squeeze film force on a rigid disk undergoing small axial oscillations
S. Ramanarayanan, W. Coenen, A. L. Sánchez, J. Fluid Mech., 933 A15 (2022). [DOI] - On the enhanced attractive load capacity of resonant flexural squeeze-film levitators
S. Ramanarayanan, A. L. Sánchez, AIP Adv., 12 105126 (2022). [DOI] - Benefits of controlled inclination for contactless transport by squeeze-film levitation
S.Ramanarayanan, A. L. Sánchez, Flow, 3, E26 (2023). [DOI] - Controlling the Motion of Gas-Lubricated Adhesive Disks using Multiple Vibration Sources
J. Chengzhe, S.Ramanarayanan, A. L. Sánchez, M. T. Tolley, Front. Robot. AI, section Soft Robotics, 10, 1231976 (2023) [DOI]
- Viscoacoustic squeeze film force on a rigid disk undergoing small axial oscillations
Streaming flows
The interaction of an oscillating stream with solid boundaries is known to result in a time-averaged steady-streaming motion. This phenomenon plays a crucial role in a wide range of applications including environmental flows, transport in physiological systems, and microscale fluid devices.
Lagrangian motion in oscillatory flow over a cylinder array.
Two-dimensional flow in a wedge driven by a time-dependent surface heat flux as a model problem to understand buoyancy-induced cross-shore flow.
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- Residual streaming flows in buoyancy- driven cross-shore exchange
W. Coenen, A. L. Sánchez, R. Félez, K.A. Davis, G. Pawlak, J. Fluid Mech., 920 A1 (2021). [DOI] - Oscillating viscous flow past a streamwise linear array of circular cylinders
J. Alaminos-Quesada, J.J. Lawrence, W. Coenen, A. L. Sánchez, J. Fluid Mech., 959, A39 (2023). [DOI] - Stationary flow driven by non-sinusoidal time-periodic pressure gradients in wavy-walled channels
J. Alaminos-Quesada, C. Gutiérrez-Montes, W. Coenen, A. L. Sánchez, Appl. Math. Model., 122, 693-705 (2023) [DOI]
- Residual streaming flows in buoyancy- driven cross-shore exchange