The other recommended
correlations for the vertical upward flow and for the entire range of
the void fraction are the Hasan [28] and Nicklin et al. [23].Whereas
for vertical downward orientation in addition to Gomez et al. [22]
correlation, Cai et al. [27] and Rouhani and Axelsson [24] are the
other two recommended void fraction correlations. The performance
of the Rouhani and Axelsson [24] and Gomez et al. [22]
against different fluid combinations for vertical upward and downward
flow is shown in Figs. 17 and 18, respectively.