Modeling in prediction of microgravity two-phase slug–annular flow pattern transition

The phenomenon of two-phase slug–annular flow pattern transition under microgravity condition has been modeled in the range of low to moderately high gas flow rates. It has been established that the transition can be predicted from the known values of superficial Weber number of the phases. Thus, the model extends a physical basis to the existing empirical result which is based on the same dimensionless groups. It has further been demonstrated that the performance of the model in correctly delineating slug–annular transition is better than any other existing model. Embodying the effect of still higher gas flow rates, another transition model has been developed to show that an equation consisting of Suratman number and ratio of gas to liquid Reynolds numbers can be constructed to predict the transition. This result makes an attempt to explore the physical basis of the existing empirical equation which also consists of these dimensionless groups. However, additional reliable data are needed to judge the relative merit of this latter model.