One-dimensional interfacial area transport of vertical upward bubbly flow in narrow rectangular channel

► Experiments are performed in vertical narrow rectangular channel. ► Local data of IAC and others are measured by imaging processing technique. ► Developing two-phase flow is characterized by great changes of local parameters. ► Existing frictional multiplier correlations and drift-flux models are verified. ► Existing IAC model is modified to predict the IAC and the Sauter mean diameter.