Abstract
The prediction of flow patterns is the basis for modeling the two-phase flow and heat transfer. The annular flow transition is the most important phenomenon and the several models have been proposed. As the body forces largely control the flow behavior, gravity is a key parameter in the transition models. However, it has been very difficult to prove its influence. The existing transition models were compared with the experimental results at microgravity conditions during parabolic trajectory flights on aircraft. The influence of gravity on the annular flow transition was discussed and the existing models were verified.
