Understanding and predicting phase distribution in two-phase flows has been a goal of many researchers for the past half-century. Industry has many interesting and challenging problems in two-phase flow which are concerned with multidimensional phase distribution phenomena. This research has focused on developing a fundamental understanding and predictive capability for the phase distribution in laminar bubbly two-phase flows. To achieve this capability an understanding of the fundamental physics that controls the bubble distribution was developed. Using ensemble averaging techniques, phasic conservation equations for the dispersed bubbles and the continuous liquid were derived. These two-fluid, ensemble-averaged conservation equations, and the associated mechanistically based closure laws were embodied into a predictive tool. The tool developed was a computer-based FORTRAN program which contained a discretized set of the governing equations using finite element theory.;This computer code was able to predict the dispersed bubbles and continuous liquid velocities as well as the distribution of the bubbles in circular pipes having variable area cross-sections. The tool predicts the wall skewed void profile which has been measured experimentally for cocurrent bubbly upflow in a vertical pipe. The fully developed pipe flow predictions for cocurrent bubbly upflow were compared to experimental data and shown to agree well. Predictions of bubbly downflow show a flattened void profile with zero void fraction near the walls. This profile has been observed experimentally in turbulent bubbly downflow. The computer code was also used to predict the phase distribution in sudden pipe expansions and contractions as well as diverging and converging nozzles. These geometries were used to investigate the characteristics and robustness of the two-fluid bubbly flow model. These cases emphasis the strong interplay between the bubbly flow model and the local velocity and void profiles. As the various interfacial bubbly flow models became important the bubble motion was affected which significantly influenced the resulting phasic velocity and phase distribution.;Modelling and including the bubbly flow forces in a two-fluid formulation was needed to develop an engineering tool which can predict bubbly flows in a wide range of geometries and conditions. Reaching this milestone represents a key step toward developing a more accurate and robust engineering tool which can predict a broader range of multiphase flows.
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