Figs. 15 and 16 show the prediction of the Gomez et al. [22] correlation
using positive and negative values of the drift velocity
against void fraction data for vertical downward flow. The Gomez
et al. [22] correlation takes care of low values of void fraction in
upward and high values of void fraction in downward orientation
merely by flipping the sign of the drift velocity automatically due
to the inclusion of sinh term in its physical structure.