The comparison as indicated in Fig. 4 reveals that, in general,
the present data correspond well with the transition zones proposed
by Revellin and Thome [20]. The regions of churn flow and
throat-annular flow obtained from the present study agree fairly
well with their coalescing bubble regime whereas our annular flow
and annular-rivulet flow are located in their annular region. The
present slug flow data are found near the transition zone between
their isolated bubble and coalescing bubble regions.