Two-group drift-flux model in boiling flow

Caleb S. Brooks, Basar Ozar, Takashi Hibiki, Mamoru Ishii

Research output: Contribution to journalArticlepeer-review


The two-group two-fluid model with interfacial area transport equation has been developed to improve the prediction of void fraction and heat transfer characteristics in two-phase systems. In the one-dimensional formulation, a closure relation is required for the group-1 and group-2 area-average local relative velocity. Furthermore, in the case of the modified two-fluid model with the gas-mixture momentum equation, the group-1 and group-2 void weighted gas velocities must be calculated with additional closure relations. The drift-flux general expression is extended to two bubble groups in order to describe the group-1 and group-2 void weighted gas velocities and area-averaged local relative velocities. Correlations for group-1 and group-2 distribution parameters and drift velocities are proposed and evaluated with a two-group boiling dataset taken in an internally heated annulus. The proposed distribution parameters show an average agreement within ±5%. The overall estimation of group-1 and group-2 void weighted gas velocities calculated with the newly proposed two-group drift-flux general expression shows an average agreement within ±16% of the measured value. The equations obtained for area-averaged relative velocity of group-1 and group-2 bubbles were simplified by neglecting covariance in void fraction. This assumption was compared with the experimental database and resulted in an average error within ±13%.

Original languageEnglish (US)
Pages (from-to)6121-6129
Number of pages9
JournalInternational Journal of Heat and Mass Transfer
Issue number21-22
StatePublished - Oct 2012
Externally publishedYes


  • Annulus
  • Boiling
  • Drift flux model
  • Relative velocity
  • Two-fluid model

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


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