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Near-Field Acousto Monitoring Shear Interactions Inside a Drop of Fluid: The Role of the Zero-Slip condition
Physics of Fluids
  • Xiaohua Wang, Portland State University
  • Rodolfo Fernandez Rodriguez, Portland State University
  • Nan Li, Bronx Science High School
  • Hsien-Chih Hung, Portland State University
  • Anuradha Venkataraman, Portland State University
  • Richard Nordstrom, Portland State University
  • Andres H. La Rosa, Portland State University
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Publication Date
  • Near-field microscopy

A full understanding of nanometer-range (near-field) interactions between two sliding solid boundaries, with a mesoscopic fluid layer sandwiched in between, remains challenging. In particular, the origin of the blue-shift resonance frequency experienced by a laterally oscillating probe when approaching a substrate is still a matter of controversy. A simpler problem is addressed here, where a laterally oscillating solid probe interacts with a more sizable drop of fluid that rests on a substrate, aiming at identifying interaction mechanisms that could also be present in the near-field interaction case. It is found that the inelastic component of the probe-fluid interaction does not constitute the main energy-dissipation channel and has a weak dependence on fluid’s viscosity, which is attributed to the zero-slip hydrodynamic condition. In contrast, the acoustic signal engendered by the fluid has a stronger dependence on the fluid’s viscosity(attributed also to the zero-slip hydrodynamic condition) and correlates well with the probe’s resonancefrequency red-shift. We propose a similar mechanism happens in near field experiments, but a blue-shift in the probe’s resonance results as a consequence of the fluid molecules (subjected to the zero-slip condition at both the probe and substrate boundaries) exerting instead a spring type restoring force on the probe.


This is the Accepted Manuscript (AM) version of the article and was originally published in Physics of Fluids; 28, 052001 (2016) and can be found online at:

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Xiaohua Wang, Rodolfo Fernandez Rodriguez, Nan Li, Hsien-Chih Hung, et al.. "Near-Field Acousto Monitoring Shear Interactions Inside a Drop of Fluid: The Role of the Zero-Slip condition" Physics of Fluids (2016)
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