Non-axisymmetric instability of core—annular flow

Howard H. Hu, Neelesh Patankar

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Stability of core—annular flow of water and oil in a vertical circular pipe is studied with respect to non-axisymmetric disturbances. Results show that when the oil core is thin, the flow is most unstable to the asymmetric sinuous mode of disturbance, and the core moves in the form of corkscrew waves as observed in experiments. The asymmetric mode of disturbance is the most dangerous mode for quite a wide range of material and flow parameters. This asymmetric mode persists in vertical pipes with upward and downward flows and in horizontal pipes. The analysis also applies to the instability of freely rising axisymmetric cigarette smoke or a thermal plume. The study predicts a unique wavelength for the asymmetric meandering waves.

Original languageEnglish (US)
Pages (from-to)213-224
Number of pages12
JournalJournal of fluid Mechanics
StatePublished - May 1995

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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