Slug formation mechanism for air–water system in T-junction microchannel: a numerical investigation

In this paper, numerical investigation of slug formation mechanism of gas–liquid two-phase flow in a T-junction microchannel has been carried out. A two-dimensional (2D) model for the microchannel was developed using ANSYS Academic research CFD 18.2 software package, and volume of fluid method was adopted to solve the model numerically. The results obtained are in good agreement with the experimental results. In this work, slug length, pressure drop and velocity variations inside the slugs were captured at several operating conditions. The effects of contact angle (0°–155°), fluid viscosity, and surface tension on two phase flow interaction parameters along with the effect of both gas and liquid superficial velocities are discussed in detail. For gas–liquid two phase flow velocities were ranging from 0.025 to 0.5 m s−1 and capillary number (Ca) from 6.96 × 10−4 to 1.39 × 10−2. One of the key objectives of this investigation was to study the occurrence and behaviour of liquid film around the slug units. In fact, liquid film formed at low capillary number (Ca) was very thin and observed only for fine meshing near wall of the channel.