A comparison of the performance of 54 void fraction correlations based on unbiased
experimental data set of 3385 data points. A comprehensive literature search was undertaken for the
available void fraction correlations and experimental void fraction data for upward and downward
vertical and horizontal two-phase flows. The performance of the correlations in correctly predicting the
diverse data set was evaluated. Comparisons between the correlations were made and appropriate
recommendations were drawn. The analysis showed that most of the correlations developed are very
restricted in terms of handling a wide variety of data sets. Based on this analysis void fraction
correlations with the best predictive capability are highlighted.
Keywords: Two-phase flow, void fraction, flow pattern, flow visualization, vertical and horizontal pipes.
