Linear stability of two-layer Couette flows

Alireza Mohammadi, Alexander J. Smits

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


The stability of two-layer Couette flow is investigated under variations in viscosity ratio, thickness ratio, interfacial tension and density ratio. The effects of the base flow on eigenvalue spectra are explained. A new type of interfacial mode is discovered at low viscosity ratio with properties that are different from Yih's original interfacial mode (Yih, J. Fluid Mech., vol. 27, 1967, pp. 337-352). No unstable Tollmien-Schlichting waves were found over the range of parameters considered in this work. The results for thin films with different thicknesses can be collapsed onto a single curve if the Reynolds number and wavenumber are suitably defined based on the parameters of the thin layer. Interfacial tension always has a stabilizing effect, but the effects of density ratio cannot be so easily generalized. Neutral stability curves for water-alkane and water-air systems are presented as an initial step towards better understanding the effects of flow stability on the longevity and performance of liquid-infused surfaces and superhydrophobic surfaces.

Original languageEnglish (US)
Pages (from-to)128-157
Number of pages30
JournalJournal of Fluid Mechanics
StatePublished - Sep 10 2017

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Applied Mathematics


  • channel flow
  • instability
  • multiphase flow


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