Buckling of a thin, viscous film in an axisymmetric geometry.

• Author(s) / Creator(s)

  • Craster, R. V.
  • Flynn, M.R.
  • Bhattacharya, S.

• By adapting the Föppl-von Kàrmàn equation, which describes the deformation of a thin elastic membrane, we present an analysis of the buckling pattern of a thin, very viscous fluid layer subject to shear in an axisymmetric geometry. A linear stability analysis yields a differential eigenvalue problem, whose solution, obtained using spectral techniques, yields the most unstable azimuthal wave-number, m ⋆. Contrary to the discussion of Slim et al. [J. Fluid Mech.694, 5–28 (Year: 2012)]10.1017/jfm.2011.437, it is argued that the axisymmetric problem shares the same degeneracy as its rectilinear counterpart, i.e., at the onset of instability, m ⋆ is indefinitely large. Away from this point, however, a comparison with analogue experimental results is both possible and generally favorable. In this vein, we describe the laboratory apparatus used to make new measurements of m ⋆, the phase speed and the wave amplitude; note that no prediction concerning the latter two quantities can be made using the present theory. Experiments reveal a limited range of angular velocities wherein waves of either small or large amplitude may be excited. Transition from one to the other regime does not appear to be associated with a notable change in m ⋆.

• Date created

  2013

• Subjects / Keywords

  • Surface tension
  • Buckling
  • Fluid equations
  • Viscosity
  • Shear rate dependent viscosity

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R35Q4S06K

• License

  © 2013 S. Bhattacharya et al. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.