Two-phase slug-to-annular flow pattern transition in microgravity

It has been established through the identification and evaluation of characteristic forces dominant in two-phase gas-liquid flow field that Suratman number is the key dimensionless group in slug-annular flow pattern transition under microgravity. Furthermore, the intrinsic physical mechanism underlying the transition has been explored with the aid of experimental results. It is revealed that slug-annular flow pattern transition depends on Suratman number and the ratio of superficial gas to liquid Reynolds numbers. This result provides a physical basis to the existing empirical transition equation which is based on the same two dimensionless groups. (C) 2009 Elsevier Ltd. All rights reserved.