Thermocapillary instability as a mechanism for film boiling collapse

Eskil Aursand*, Stephen H. Davis, Tor Ytrehus

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

We construct a model to investigate the interfacial stability of film boiling, and discover that instability of very thin vapour films and subsequent large interface superheating is only possible if thermocapillary instabilities are present. The model concerns horizontal saturated film boiling, and includes novel features such as non-equilibrium evaporation based on kinetic theory, thermocapillary and vapour thrust stresses and van der Waals interactions. From linear stability analysis applied to this model, we are led to suggest that vapour film collapse depends on a balance between thermocapillary instabilities and vapour thrust stabilization. This yields a purely theoretical prediction of the Leidenfrost temperature. Given that the evaporation coefficient is in the range 0.7-1.0, this model is consistent with the average Leidenfrost temperature of every fluid for which data could be found. With an evaporation coefficient of 0.85, the model can predict the Leidenfrost point within 10 % error for every fluid, including cryogens and liquid metals where existing models and correlations fail.

Original languageEnglish (US)
Pages (from-to)283-312
Number of pages30
JournalJournal of fluid Mechanics
Volume852
DOIs
StatePublished - Oct 10 2018

Keywords

  • lubrication theory
  • thermocapillarity
  • thin films

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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