A study of drift velocity in bubbly two-phase flow under microgravity conditions

The results from a numerical simulation of microgravity bubbly gas–liquid two-phase flow are presented and compared against experimental data collected during parabolic flights on NASAʹs KC-135 aircraft. The simulation produced comparable results for the drift velocity and the rate at which bubbles move towards the center of the tube. The simulations were done for a range of parameters; including the liquid Reynolds number (1000–25,000), the bubble size relative to the tube diameter (0.1–0.3), surface tension (7.28×10−2–2.18×10−1 N/m), and tube diameter (9.525–40 mm). The results showed excellent comparisons with the bubble shape and evolution, the magnitude of the drift velocity, and the distance that the bubble moves towards the tube center. It was concluded that the bubble diameter, radial bubble position, liquid Reynolds number, and tube diameter all have major influence on the drift velocity.