Abstract
In a companion paper (Zhang, H. N., Sun, H. M., Yokomine, T., Kunugi, T., Japanese J. Multiphase Flow, submitted), for upward turbulent bubbly flow (TBF) in the large square duct, the observation of the typical M-shaped velocity profile were described. The present paper further discussed its formation by considering the duct geometry effect on the ability of gathering bubbles to near the wall region and the wall shear resistance. It indicated that a large square duct owns not only stronger bubble gathering ability to the wall but also the smaller wall shear resistance, which was responsible for the formation of the typical M-shaped velocity profile. In addition, the flow characteristics were discussed based on the normalization of liquid phase velocity, which suggested the two-layer model according to the different flow types therein.
