In this work

visualization experiments were carried out in serpentine microchannels with Y-type microfluidic junction and small curvature using a high-speed camera. Visible rectangular microchannels with the equivalent diameter of the 177.8 μm were fabricated using transparent glass and polydimethylsiloxane (PDMS). Air and deionized water were well mixed in the Y-type mixer. First

gas and liquid were injected into inlets 1 and 2

respectively. And then

the order would be reversed. Flow characteristics of these two different mixing modes were compared. The main flow patterns such as slug flow

wavy stratified flow and dispersed flow were observed. In this regard

the shape and length of slug

thickness of liquid film and share of liquid droplets entrained by gas phase were investigated in succession

and a new correlation to predict droplets content was proposed based on the measured data. In addition

the arc at the corner can induce slug flow for these two different ways of mixing. Both of them were experiencing tension and fracture processes. The difference was that the latter would like to carry out expansion firstly due to the obstruction by the liquid. The gas-liquid mixture in different ways could have some impact on the flow of each phase and the distribution of two phases near the wall or in the bends was also different.