“…In the experiment of REST (Bunz et al, 1992) the range of superficial gas velocity was from 0.05 m/s corresponding to an entrainment of 1.4E-4 to a superficial gas velocity of 0.08 m/s corresponding to an entrainment of 3E-5. In the THAI experiments, , for superficial gas velocities ranging from 0.025 m/s to 0.13 m/s, entrainment values between 3E and 6 to 3E-4 are obtained whereas the entrainment reduces towards larger superficial velocities (Schmidt et al, 2015). Under such range of superficial gas velocities, the bubble cannot be considered uniformly sized (Shah et al, 1982).…”