Classification of bubbles in vertical gas-liquid flow: Part 2 - A model evaluation

Three-fluid model along with two-group average bubble number density equations have been applied for the classification of bubbles in vertical gas-liquid flow. The current study focused on (i) consideration of three-fluid model transport equations governing the conservation of mass and momentum, (ii) formulation of two-group averaged bubble number density equations, (iii) classification of bubble interaction between spherical bubbles (Group-1) and cap bubbles (Group-2), (iv) consideration of source and sink terms via the proposal of Hibiki and Ishii (Nuclear Engineering and Design 202, 39-76) in the averaged bubble number density equations and (v) assessment by means of the experimental data sets at the bubbly-to-cap flow transition. Reasonable agreement has been achieved between the measured and predicted local and axial distributions of void fraction, interfacial area concentration (IAC) and volume equivalent bubble diameter. This preliminary assessment demonstrated the capability of the current approach in capturing the interfacial transport of bubbly to cap flow transition