Two-group interfacial area transport equations at bubbly-to-slug flow transition

In relation to the development of the interfacial area transport equation, the basic concept of two-group interfacial area transport equations was demonstrated. This study focused on (1) the formulation of the two-group interfacial area transport equations, (2) the classification of bubble interactions between spherical/distorted bubbles and cap/slug bubbles, (3) the categorization of basic mechanisms of bubble coalescence and breakup, (4) the preliminary modeling of sink and source terms in the interfacial area transport equation, (5) the construction of several data sets at bubbly-to-slug flow transition by assuming the shape of a cap bubble, and (6) the validation of the two-group interfacial area transport equations by means of the data sets at the bubbly-to-slug flow transition. Excellent agreement was obtained between predicted and measured interfacial area concentrations within the average relative deviation of ±3.61% for seven data sets. It was expected that this preliminary work would serve to show the capability of the two-group interfacial area transport equations as well as to understand the basic behavior of the interfacial area transport at the transition from bubbly to slug flow.